How to use this page
This page is a large, topic-wise collection of Java practical file programs. Instead of a flat list, the programs are grouped by the concept they teach - conditions, loops, arrays, strings, methods and classes, switch case, and exception handling. Each group has seven or eight short programs written in the same simple, exam-friendly style as a real Class 12 IT (802) practical file.
Every program shows its full code and expected output. Below the lesson you will find a built-in Live Code Editor - the programs load into it automatically, so you can pick any one, press Run, edit it, and see the result instantly without installing anything. For programs that read input with Scanner, type your values into the editor's input box.
if / if-else / if-else-if programs
Maximum of three integers
Reads three numbers and prints the largest using an if - else if chain.
import java.util.Scanner;
public class BigThree {
public static void main(String[] args) {
int a,b,c;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter First Number");
a=obj1.nextInt();
System.out.println("Enter Second Number");
b=obj1.nextInt();
System.out.println("Enter Third Number");
c=obj1.nextInt();
if(a>b && a>c)
System.out.println("Big number is "+a);
else if(b>a && b>c)
System.out.println("Big number is "+b);
else
System.out.println("Big number is "+c);
}
}
Output:
Enter First Number
45
Enter Second Number
78
Enter Third Number
47
Big number is 78
Even or odd number
Uses the modulus operator to check if a number is divisible by 2.
import java.util.Scanner;
public class EvenOdd {
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
if(n%2==0)
System.out.println("Number is Even");
else
System.out.println("Number is Odd");
}
}
Output:
Enter a Number
10
Number is Even
Positive, negative or zero
Checks the sign of a number with an if-else-if chain.
import java.util.Scanner;
public class SignCheck {
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
if(n>0)
System.out.println("Number is Positive");
else if(n<0)
System.out.println("Number is Negative");
else
System.out.println("Number is Zero");
}
}
Output:
Enter a Number
-5
Number is Negative
Largest of two numbers
A simple if-else to compare two values.
import java.util.Scanner;
public class BigTwo {
public static void main(String[] args) {
int a,b;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter First Number");
a=obj1.nextInt();
System.out.println("Enter Second Number");
b=obj1.nextInt();
if(a>b)
System.out.println("Bigger is "+a);
else
System.out.println("Bigger is "+b);
}
}
Output:
Enter First Number
12
Enter Second Number
20
Bigger is 20
Check leap year
A year is leap if divisible by 4 and not 100, unless divisible by 400.
import java.util.Scanner;
public class LeapYear {
public static void main(String[] args) {
int year;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter an Year:");
year=obj1.nextInt();
if(((year%4==0) && (year%100!=0)) || (year%400==0))
System.out.println("Year is a leap year");
else
System.out.println("Year is not a leap year");
}
}
Output:
Enter an Year:
2024
Year is a leap year
Voting eligibility
Checks whether age is 18 or above.
import java.util.Scanner;
public class VoteCheck {
public static void main(String[] args) {
int age;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter your Age");
age=obj1.nextInt();
if(age>=18)
System.out.println("You are eligible to vote");
else
System.out.println("You are not eligible to vote");
}
}
Output:
Enter your Age
20
You are eligible to vote
Grade using marks
Uses an if-else-if ladder to assign a grade from marks.
import java.util.Scanner;
public class GradeCheck {
public static void main(String[] args) {
int marks;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Marks");
marks=obj1.nextInt();
if(marks>=90)
System.out.println("Grade A");
else if(marks>=70)
System.out.println("Grade B");
else if(marks>=50)
System.out.println("Grade C");
else
System.out.println("Fail");
}
}
Output:
Enter Marks
75
Grade B
Number divisible by 5 and 11
Checks two conditions together with the AND operator.
import java.util.Scanner;
public class DivCheck {
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
if(n%5==0 && n%11==0)
System.out.println("Divisible by both 5 and 11");
else
System.out.println("Not divisible by both");
}
}
Output:
Enter a Number
55
Divisible by both 5 and 11
Loop programs (for, while, do-while)
Print even and odd 1 to 10
A for loop from 1 to 10 printing whether each number is even or odd.
public class EvenOddList {
public static void main(String[] args) {
int i;
for(i=1;i<=10;i++)
{
if(i%2==0)
System.out.println("Number " +i+ " is Even");
else
System.out.println("Number "+i+ " is Odd ");
}
}
}
Output:
Number 1 is Odd
Number 2 is Even
...
Number 10 is Even
Factorial of a number
Multiplies all numbers from n down to 1 using a loop.
import java.util.Scanner;
public class Factorial {
public static void main(String[] args) {
int n,fact=1,i;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
for(i=n;i>=1;i--)
{
fact=fact*i;
}
System.out.println("Factorial is "+fact);
}
}
Output:
Enter a Number
5
Factorial is 120
Fibonacci series (10 terms)
Each number is the sum of the previous two, printed for 10 terms.
public class Fibonacci {
public static void main(String[] args) {
int a,b,c,i;
a=0;
b=1;
System.out.println(a);
System.out.println(b);
for(i=3;i<=10;i++)
{
c=a+b;
System.out.println(c);
a=b;
b=c;
}
}
}
Output:
0
1
1
2
3
5
8
13
21
34
Sum of even numbers 1 to 100
Adds every even number between 1 and 100.
public class SumEven {
public static void main(String[] args) {
int i,sum=0;
for(i=1;i<=100;i++)
{
if(i%2==0)
sum=sum+i;
}
System.out.println("Sum is "+sum);
}
}
Output:
Sum is 2550
Multiplication table
Prints the table of a number using a for loop.
import java.util.Scanner;
public class Table {
public static void main(String[] args) {
int n,i;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
for(i=1;i<=10;i++)
{
System.out.println(n+" x "+i+" = "+(n*i));
}
}
}
Output:
Enter a Number
5
5 x 1 = 5
5 x 2 = 10
...
5 x 10 = 50
Reverse of a number
Uses a while loop to reverse the digits of a number.
import java.util.Scanner;
public class ReverseNum {
public static void main(String[] args) {
int n,rev=0,r;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a number");
n=obj1.nextInt();
while(n>0)
{
r=n%10;
rev=rev*10+r;
n=n/10;
}
System.out.println(rev);
}
}
Output:
Enter a number
123
321
Sum of digits
Adds all digits of a number using a while loop.
import java.util.Scanner;
public class SumDigits {
public static void main(String[] args) {
int n,sum=0,r;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a number");
n=obj1.nextInt();
while(n>0)
{
r=n%10;
sum=sum+r;
n=n/10;
}
System.out.println("Sum of digits is "+sum);
}
}
Output:
Enter a number
123
Sum of digits is 6
Print numbers with do-while
Shows the do-while loop, which always runs at least once.
public class DoWhileDemo {
public static void main(String[] args) {
int i=1;
do
{
System.out.println("Count "+i);
i++;
}
while(i<=5);
}
}
Output:
Count 1
Count 2
Count 3
Count 4
Count 5
Array programs
Largest element in an array
Stores 10 numbers and finds the biggest by scanning through.
import java.util.Scanner;
public class ArrayMax {
public static void main(String[] args) {
int i;
int [] arr = new int [10];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 10 numbers");
for(i=0;i<10;i++)
{
arr[i]=obj1.nextInt();
}
int max = arr[0];
for (i = 0; i < arr.length; i++)
{
if(arr[i] > max)
max = arr[i];
}
System.out.println("Largest element is: " + max);
}
}
Output:
Enter 10 numbers
25 78 28 22 45 90 34 59 12 5
Largest element is: 90
Smallest element in an array
Same scan pattern but keeps the minimum value.
import java.util.Scanner;
public class ArrayMin {
public static void main(String[] args) {
int i;
int [] arr = new int [10];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 10 numbers");
for(i=0;i<10;i++)
{
arr[i]=obj1.nextInt();
}
int min = arr[0];
for (i = 0; i < arr.length; i++)
{
if(arr[i] < min)
min = arr[i];
}
System.out.println("Smallest element is: " + min);
}
}
Output:
Enter 10 numbers
25 78 28 22 45 90 34 59 12 5
Smallest element is: 5
Sum of array elements
Adds all values stored in the array.
import java.util.Scanner;
public class ArraySum {
public static void main(String[] args) {
int i,sum=0;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
}
for(i=0;i<5;i++)
{
sum=sum+arr[i];
}
System.out.println("Sum is "+sum);
}
}
Output:
Enter 5 numbers
10 20 30 40 50
Sum is 150
Average of array elements
Finds the sum then divides by the count.
import java.util.Scanner;
public class ArrayAvg {
public static void main(String[] args) {
int i,sum=0;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
sum=sum+arr[i];
}
System.out.println("Average is "+(sum/5.0));
}
}
Output:
Enter 5 numbers
10 20 30 40 50
Average is 30.0
Search an element in array
Linear search that checks each element for a match.
import java.util.Scanner;
public class ArraySearch {
public static void main(String[] args) {
int i,key,f=0;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
}
System.out.println("Enter number to search");
key=obj1.nextInt();
for(i=0;i<5;i++)
{
if(arr[i]==key)
{
f=1;
break;
}
}
if(f==1)
System.out.println("Element found");
else
System.out.println("Element not found");
}
}
Output:
Enter 5 numbers
10 20 30 40 50
Enter number to search
30
Element found
Reverse an array
Prints array elements from last to first.
import java.util.Scanner;
public class ArrayReverse {
public static void main(String[] args) {
int i;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
}
System.out.println("Reversed array:");
for(i=4;i>=0;i--)
{
System.out.println(arr[i]);
}
}
}
Output:
Enter 5 numbers
10 20 30 40 50
Reversed array:
50
40
30
20
10
Count even and odd in array
Counts how many elements are even and how many are odd.
import java.util.Scanner;
public class ArrayEvenOdd {
public static void main(String[] args) {
int i,ec=0,oc=0;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
if(arr[i]%2==0)
ec++;
else
oc++;
}
System.out.println("Even count: "+ec);
System.out.println("Odd count: "+oc);
}
}
Output:
Enter 5 numbers
10 15 20 25 30
Even count: 3
Odd count: 2
String programs
Convert string to upper case
Uses the built-in toUpperCase() method.
import java.util.Scanner;
public class UpperCase {
public static void main(String[] args) {
String myname;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Name in lower case");
myname=obj1.nextLine();
System.out.println("Upper case string is :"+myname.toUpperCase());
}
}
Output:
Enter a Name in lower case
alpine
Upper case string is :ALPINE
Convert string to lower case
Uses the built-in toLowerCase() method.
import java.util.Scanner;
public class LowerCase {
public static void main(String[] args) {
String myname;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Name in UPPER case");
myname=obj1.nextLine();
System.out.println("Lower case string is :"+myname.toLowerCase());
}
}
Output:
Enter a Name in UPPER case
ALPINE
Lower case string is :alpine
Count vowels and consonants
Walks each character and counts vowels and consonants.
import java.util.Scanner;
public class VowelCount {
public static void main(String[] args) {
int count_v = 0, count_c = 0;
String mystring;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a String");
mystring=obj1.nextLine();
mystring = mystring.toLowerCase();
for(int i = 0; i < mystring.length(); i++) {
if(mystring.charAt(i) == 'a' || mystring.charAt(i) == 'e' ||
mystring.charAt(i) == 'i' || mystring.charAt(i) == 'o' || mystring.charAt(i) == 'u')
count_v=count_v+1 ;
else if(mystring.charAt(i) >= 'a' && mystring.charAt(i)<='z')
count_c=count_c+1;
}
System.out.println("Number of vowels: " + count_v);
System.out.println("Number of consonants: " + count_c);
}
}
Output:
Enter a String
alpine public school
Number of vowels: 7
Number of consonants: 11
Length of a string
Uses the length() method to count characters.
import java.util.Scanner;
public class StringLength {
public static void main(String[] args) {
String s;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a String");
s=obj1.nextLine();
System.out.println("Length is "+s.length());
}
}
Output:
Enter a String
alpine
Length is 6
Reverse a string
Builds the reversed text character by character from the end.
import java.util.Scanner;
public class StringReverse {
public static void main(String[] args) {
String s,rev="";
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a String");
s=obj1.nextLine();
for(int i=s.length()-1;i>=0;i--)
{
rev=rev+s.charAt(i);
}
System.out.println("Reverse is "+rev);
}
}
Output:
Enter a String
alpine
Reverse is enipla
Check palindrome string
Reverses the string and compares it with the original.
import java.util.Scanner;
public class Palindrome {
public static void main(String[] args) {
String s,rev="";
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a String");
s=obj1.nextLine();
for(int i=s.length()-1;i>=0;i--)
{
rev=rev+s.charAt(i);
}
if(s.equals(rev))
System.out.println("It is a Palindrome");
else
System.out.println("Not a Palindrome");
}
}
Output:
Enter a String
madam
It is a Palindrome
Count words in a sentence
Splits the sentence by spaces and counts the parts.
import java.util.Scanner;
public class WordCount {
public static void main(String[] args) {
String s;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Sentence");
s=obj1.nextLine();
String[] words = s.split(" ");
System.out.println("Number of words: "+words.length);
}
}
Output:
Enter a Sentence
alpine public school
Number of words: 3
Method and Class programs
Area of circle using a method
Moves the area formula into its own method that returns a value.
import java.util.Scanner;
public class CircleArea {
public static double area_circle(double r)
{
double area;
area=3.14*r*r;
return(area);
}
public static void main(String[] args) {
double r,area;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Radius");
r=obj1.nextDouble();
area=area_circle(r);
System.out.println("Area of Circle is :"+area);
}
}
Output:
Enter Radius
4
Area of Circle is :50.24
Rectangle class and area method
Creates a separate class with a method and calls it via an object.
class Rectangle{
int length;
int width;
int area_calculate(int l, int w){
int area;
area=l*w;
return area;
}
}
public class RectangleArea {
public static void main(String args[]){
int area;
Rectangle r1=new Rectangle();
area=r1.area_calculate(11,5);
System.out.println("Area is : "+area);
}
}
Output:
Area is : 55
Sum of two numbers using a method
A method that takes two numbers and returns their sum.
import java.util.Scanner;
public class SumMethod {
public static int add(int a, int b)
{
return a+b;
}
public static void main(String[] args) {
int x,y;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter two numbers");
x=obj1.nextInt();
y=obj1.nextInt();
System.out.println("Sum is "+add(x,y));
}
}
Output:
Enter two numbers
10 20
Sum is 30
Factorial using a method
Separates the factorial logic into a returnable method.
import java.util.Scanner;
public class FactMethod {
public static int fact(int n)
{
int f=1,i;
for(i=n;i>=1;i--)
f=f*i;
return f;
}
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
System.out.println("Factorial is "+fact(n));
}
}
Output:
Enter a Number
5
Factorial is 120
Student class with details
Defines a class with fields and a method to display them.
class Student{
int roll;
String name;
void show(){
System.out.println("Roll: "+roll);
System.out.println("Name: "+name);
}
}
public class StudentDemo {
public static void main(String[] args) {
Student s1=new Student();
s1.roll=1;
s1.name="Aarav";
s1.show();
}
}
Output:
Roll: 1
Name: Aarav
Simple interest using a method
A method computes simple interest from p, r and t.
import java.util.Scanner;
public class SimpleInterest {
public static double si(double p, double r, double t)
{
return (p*r*t)/100;
}
public static void main(String[] args) {
double p,r,t;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Principal, Rate, Time");
p=obj1.nextDouble();
r=obj1.nextDouble();
t=obj1.nextDouble();
System.out.println("Simple Interest is "+si(p,r,t));
}
}
Output:
Enter Principal, Rate, Time
1000 5 2
Simple Interest is 100.0
Check even using a method
A method returns true or false for even numbers.
import java.util.Scanner;
public class EvenMethod {
public static boolean isEven(int n)
{
if(n%2==0)
return true;
else
return false;
}
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
if(isEven(n))
System.out.println("Even");
else
System.out.println("Odd");
}
}
Output:
Enter a Number
8
Even
switch case programs
Day name from number
Reads a day number 1 to 7 and prints its name.
import java.util.Scanner;
public class DayName {
public static void main(String[] args) {
int day;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Day Number");
day=obj1.nextInt();
switch(day)
{
case 1: System.out.println("Sunday"); break;
case 2: System.out.println("Monday"); break;
case 3: System.out.println("Tuesday"); break;
case 4: System.out.println("Wednesday"); break;
case 5: System.out.println("Thursday"); break;
case 6: System.out.println("Friday"); break;
case 7: System.out.println("Saturday"); break;
default: System.out.println("Invalid Day Number");
}
}
}
Output:
Enter Day Number
5
Thursday
Simple calculator
Uses switch on an operator symbol to pick the operation.
import java.util.Scanner;
public class Calculator {
public static void main(String[] args) {
int a,b;
char op;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter two numbers");
a=obj1.nextInt();
b=obj1.nextInt();
System.out.println("Enter operator (+ - * /)");
op=obj1.next().charAt(0);
switch(op)
{
case '+': System.out.println(a+b); break;
case '-': System.out.println(a-b); break;
case '*': System.out.println(a*b); break;
case '/': System.out.println(a/b); break;
default: System.out.println("Invalid operator");
}
}
}
Output:
Enter two numbers
10 5
Enter operator (+ - * /)
+
15
Month name from number
Prints the month name for a number 1 to 12.
import java.util.Scanner;
public class MonthName {
public static void main(String[] args) {
int m;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Month Number");
m=obj1.nextInt();
switch(m)
{
case 1: System.out.println("January"); break;
case 2: System.out.println("February"); break;
case 3: System.out.println("March"); break;
case 4: System.out.println("April"); break;
case 5: System.out.println("May"); break;
case 6: System.out.println("June"); break;
default: System.out.println("Enter 1 to 6");
}
}
}
Output:
Enter Month Number
3
March
Vowel or consonant
Uses switch to check if a character is a vowel.
import java.util.Scanner;
public class VowelSwitch {
public static void main(String[] args) {
char ch;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a character");
ch=obj1.next().charAt(0);
switch(ch)
{
case 'a':
case 'e':
case 'i':
case 'o':
case 'u': System.out.println("Vowel"); break;
default: System.out.println("Consonant");
}
}
}
Output:
Enter a character
e
Vowel
Grade from choice
Prints a message based on a grade letter using switch.
import java.util.Scanner;
public class GradeSwitch {
public static void main(String[] args) {
char g;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Grade (A B C)");
g=obj1.next().charAt(0);
switch(g)
{
case 'A': System.out.println("Excellent"); break;
case 'B': System.out.println("Good"); break;
case 'C': System.out.println("Average"); break;
default: System.out.println("Invalid Grade");
}
}
}
Output:
Enter Grade (A B C)
A
Excellent
Arithmetic menu
A menu-driven program using switch for choices.
import java.util.Scanner;
public class MenuSwitch {
public static void main(String[] args) {
int choice,a=12,b=4;
Scanner obj1=new Scanner(System.in);
System.out.println("1.Add 2.Sub 3.Mul");
System.out.println("Enter choice");
choice=obj1.nextInt();
switch(choice)
{
case 1: System.out.println("Sum = "+(a+b)); break;
case 2: System.out.println("Diff = "+(a-b)); break;
case 3: System.out.println("Product = "+(a*b)); break;
default: System.out.println("Wrong choice");
}
}
}
Output:
1.Add 2.Sub 3.Mul
Enter choice
1
Sum = 16
Number in words (1-5)
Prints the word form of a small number using switch.
import java.util.Scanner;
public class NumberWords {
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a number (1-5)");
n=obj1.nextInt();
switch(n)
{
case 1: System.out.println("One"); break;
case 2: System.out.println("Two"); break;
case 3: System.out.println("Three"); break;
case 4: System.out.println("Four"); break;
case 5: System.out.println("Five"); break;
default: System.out.println("Enter 1 to 5");
}
}
}
Output:
Enter a number (1-5)
3
Three
Exception handling programs
Divide by zero exception
try-catch handles ArithmeticException so the program does not crash.
import java.util.Scanner;
public class DivZero {
public static void main(String[] args) {
int divi,divis,sum;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Dividend Number");
divi=obj1.nextInt();
System.out.println("Enter Divisor Number");
divis=obj1.nextInt();
try
{
System.out.println(divi/divis);
}
catch (ArithmeticException e)
{
System.out.println("Divided by zero operation cannot possible");
}
sum=divi+divis;
System.out.println("sum is :"+sum);
}
}
Output:
Enter Dividend Number
34
Enter Divisor Number
0
Divided by zero operation cannot possible
sum is :34
Array index out of bounds
Catches ArrayIndexOutOfBoundsException on invalid index.
public class ArrayIndex {
public static void main(String[] args) {
int [] arr = {10,20,30};
try
{
System.out.println(arr[5]);
}
catch (ArrayIndexOutOfBoundsException e)
{
System.out.println("Invalid array index");
}
}
}
Output:
Invalid array index
Number format exception
Catches an error when a non-number string is parsed.
public class NumFormat {
public static void main(String[] args) {
try
{
int n=Integer.parseInt("abc");
System.out.println(n);
}
catch (NumberFormatException e)
{
System.out.println("Not a valid number");
}
}
}
Output:
Not a valid number
Null pointer exception
Catches an error when using a null reference.
public class NullDemo {
public static void main(String[] args) {
String s=null;
try
{
System.out.println(s.length());
}
catch (NullPointerException e)
{
System.out.println("Null value cannot be used");
}
}
}
Output:
Null value cannot be used
try-catch-finally
Shows that the finally block always runs.
public class FinallyDemo {
public static void main(String[] args) {
try
{
int x=10/0;
}
catch (ArithmeticException e)
{
System.out.println("Cannot divide by zero");
}
finally
{
System.out.println("This always runs");
}
}
}
Output:
Cannot divide by zero
This always runs
Throw a custom message
Uses throw to raise an exception with a message.
import java.util.Scanner;
public class ThrowDemo {
public static void main(String[] args) {
int age;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter age");
age=obj1.nextInt();
try
{
if(age<18)
throw new ArithmeticException("Not an adult");
System.out.println("You are an adult");
}
catch (ArithmeticException e)
{
System.out.println("Error: "+e.getMessage());
}
}
}
Output:
Enter age
15
Error: Not an adult
Multiple catch blocks
Handles two different exceptions with separate catch blocks.
public class MultiCatch {
public static void main(String[] args) {
try
{
int [] arr = new int[3];
arr[5]=10/0;
}
catch (ArithmeticException e)
{
System.out.println("Arithmetic problem");
}
catch (ArrayIndexOutOfBoundsException e)
{
System.out.println("Array problem");
}
}
}
Output:
Arithmetic problem
Summary
- Programs are grouped by topic, with 7-8 in each group, for focused practice.
- Every program has real code and output in the standard practical-file style.
- The built-in Live Code Editor runs any program in your browser - no install needed.
- Use the STDIN box for programs that read input with Scanner.
Build the fundamentals first with Introduction to Java, learn input in User Input using Scanner, or try more in 68 Java Practice Programs.
इस page को कैसे इस्तेमाल करें
यह page Java practical file programs का एक बड़ा, topic-wise संग्रह है। सपाट list के बजाय, programs उस concept के हिसाब से समूह में हैं जो वे सिखाते हैं - conditions, loops, arrays, strings, methods और classes, switch case, और exception handling। हर समूह में सात-आठ छोटे programs हैं, उसी सरल, exam-friendly शैली में जो एक असली Class 12 IT (802) practical file की होती है।
हर program अपना पूरा code और अपेक्षित output दिखाता है। lesson के नीचे आपको एक built-in Live Code Editor मिलेगा - programs उसमें अपने-आप load हो जाते हैं, तो आप कोई भी चुनकर Run दबा सकते हैं, edit कर सकते हैं, और बिना कुछ install किए तुरंत result देख सकते हैं। जो programs Scanner से input पढ़ते हैं, उनके लिए editor के input box में अपनी values type कीजिए।
if / if-else / if-else-if programs
तीन integers में सबसे बड़ा
तीन numbers पढ़कर if - else if श्रृंखला से सबसे बड़ा print करता है।
import java.util.Scanner;
public class BigThree {
public static void main(String[] args) {
int a,b,c;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter First Number");
a=obj1.nextInt();
System.out.println("Enter Second Number");
b=obj1.nextInt();
System.out.println("Enter Third Number");
c=obj1.nextInt();
if(a>b && a>c)
System.out.println("Big number is "+a);
else if(b>a && b>c)
System.out.println("Big number is "+b);
else
System.out.println("Big number is "+c);
}
}
Output:
Enter First Number
45
Enter Second Number
78
Enter Third Number
47
Big number is 78
संख्या even है या odd
modulus operator से जाँचता है कि संख्या 2 से भाज्य है या नहीं।
import java.util.Scanner;
public class EvenOdd {
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
if(n%2==0)
System.out.println("Number is Even");
else
System.out.println("Number is Odd");
}
}
Output:
Enter a Number
10
Number is Even
धनात्मक, ऋणात्मक या शून्य
if-else-if श्रृंखला से संख्या का चिह्न जाँचता है।
import java.util.Scanner;
public class SignCheck {
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
if(n>0)
System.out.println("Number is Positive");
else if(n<0)
System.out.println("Number is Negative");
else
System.out.println("Number is Zero");
}
}
Output:
Enter a Number
-5
Number is Negative
दो संख्याओं में बड़ी
दो values की तुलना के लिए सरल if-else।
import java.util.Scanner;
public class BigTwo {
public static void main(String[] args) {
int a,b;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter First Number");
a=obj1.nextInt();
System.out.println("Enter Second Number");
b=obj1.nextInt();
if(a>b)
System.out.println("Bigger is "+a);
else
System.out.println("Bigger is "+b);
}
}
Output:
Enter First Number
12
Enter Second Number
20
Bigger is 20
Leap year जाँचें
साल leap है अगर 4 से भाज्य पर 100 से नहीं, जब तक 400 से भाज्य न हो।
import java.util.Scanner;
public class LeapYear {
public static void main(String[] args) {
int year;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter an Year:");
year=obj1.nextInt();
if(((year%4==0) && (year%100!=0)) || (year%400==0))
System.out.println("Year is a leap year");
else
System.out.println("Year is not a leap year");
}
}
Output:
Enter an Year:
2024
Year is a leap year
मतदान की पात्रता
जाँचता है कि उम्र 18 या उससे ज़्यादा है या नहीं।
import java.util.Scanner;
public class VoteCheck {
public static void main(String[] args) {
int age;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter your Age");
age=obj1.nextInt();
if(age>=18)
System.out.println("You are eligible to vote");
else
System.out.println("You are not eligible to vote");
}
}
Output:
Enter your Age
20
You are eligible to vote
अंकों से grade
अंकों से grade देने के लिए if-else-if ladder इस्तेमाल करता है।
import java.util.Scanner;
public class GradeCheck {
public static void main(String[] args) {
int marks;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Marks");
marks=obj1.nextInt();
if(marks>=90)
System.out.println("Grade A");
else if(marks>=70)
System.out.println("Grade B");
else if(marks>=50)
System.out.println("Grade C");
else
System.out.println("Fail");
}
}
Output:
Enter Marks
75
Grade B
5 और 11 दोनों से भाज्य
AND operator से दो शर्तें एक साथ जाँचता है।
import java.util.Scanner;
public class DivCheck {
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
if(n%5==0 && n%11==0)
System.out.println("Divisible by both 5 and 11");
else
System.out.println("Not divisible by both");
}
}
Output:
Enter a Number
55
Divisible by both 5 and 11
Loop programs (for, while, do-while)
1 से 10 तक even और odd
1 से 10 तक for loop जो बताता है हर संख्या even है या odd।
public class EvenOddList {
public static void main(String[] args) {
int i;
for(i=1;i<=10;i++)
{
if(i%2==0)
System.out.println("Number " +i+ " is Even");
else
System.out.println("Number "+i+ " is Odd ");
}
}
}
Output:
Number 1 is Odd
Number 2 is Even
...
Number 10 is Even
किसी संख्या का factorial
loop से n से 1 तक की सभी संख्याओं को गुणा करता है।
import java.util.Scanner;
public class Factorial {
public static void main(String[] args) {
int n,fact=1,i;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
for(i=n;i>=1;i--)
{
fact=fact*i;
}
System.out.println("Factorial is "+fact);
}
}
Output:
Enter a Number
5
Factorial is 120
Fibonacci series (10 पद)
हर संख्या पिछली दो का योग, 10 पद तक print।
public class Fibonacci {
public static void main(String[] args) {
int a,b,c,i;
a=0;
b=1;
System.out.println(a);
System.out.println(b);
for(i=3;i<=10;i++)
{
c=a+b;
System.out.println(c);
a=b;
b=c;
}
}
}
Output:
0
1
1
2
3
5
8
13
21
34
1 से 100 तक even का योग
1 और 100 के बीच की हर even संख्या जोड़ता है।
public class SumEven {
public static void main(String[] args) {
int i,sum=0;
for(i=1;i<=100;i++)
{
if(i%2==0)
sum=sum+i;
}
System.out.println("Sum is "+sum);
}
}
Output:
Sum is 2550
पहाड़ा (table)
for loop से किसी संख्या का पहाड़ा print करता है।
import java.util.Scanner;
public class Table {
public static void main(String[] args) {
int n,i;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
for(i=1;i<=10;i++)
{
System.out.println(n+" x "+i+" = "+(n*i));
}
}
}
Output:
Enter a Number
5
5 x 1 = 5
5 x 2 = 10
...
5 x 10 = 50
संख्या का उल्टा
while loop से संख्या के अंक उल्टे करता है।
import java.util.Scanner;
public class ReverseNum {
public static void main(String[] args) {
int n,rev=0,r;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a number");
n=obj1.nextInt();
while(n>0)
{
r=n%10;
rev=rev*10+r;
n=n/10;
}
System.out.println(rev);
}
}
Output:
Enter a number
123
321
अंकों का योग
while loop से संख्या के सभी अंक जोड़ता है।
import java.util.Scanner;
public class SumDigits {
public static void main(String[] args) {
int n,sum=0,r;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a number");
n=obj1.nextInt();
while(n>0)
{
r=n%10;
sum=sum+r;
n=n/10;
}
System.out.println("Sum of digits is "+sum);
}
}
Output:
Enter a number
123
Sum of digits is 6
do-while से numbers print
do-while loop दिखाता है, जो कम-से-कम एक बार ज़रूर चलता है।
public class DoWhileDemo {
public static void main(String[] args) {
int i=1;
do
{
System.out.println("Count "+i);
i++;
}
while(i<=5);
}
}
Output:
Count 1
Count 2
Count 3
Count 4
Count 5
Array programs
Array में सबसे बड़ा element
10 numbers रखकर scan करके सबसे बड़ा ढूँढता है।
import java.util.Scanner;
public class ArrayMax {
public static void main(String[] args) {
int i;
int [] arr = new int [10];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 10 numbers");
for(i=0;i<10;i++)
{
arr[i]=obj1.nextInt();
}
int max = arr[0];
for (i = 0; i < arr.length; i++)
{
if(arr[i] > max)
max = arr[i];
}
System.out.println("Largest element is: " + max);
}
}
Output:
Enter 10 numbers
25 78 28 22 45 90 34 59 12 5
Largest element is: 90
Array में सबसे छोटा element
वही scan pattern पर सबसे छोटी value रखता है।
import java.util.Scanner;
public class ArrayMin {
public static void main(String[] args) {
int i;
int [] arr = new int [10];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 10 numbers");
for(i=0;i<10;i++)
{
arr[i]=obj1.nextInt();
}
int min = arr[0];
for (i = 0; i < arr.length; i++)
{
if(arr[i] < min)
min = arr[i];
}
System.out.println("Smallest element is: " + min);
}
}
Output:
Enter 10 numbers
25 78 28 22 45 90 34 59 12 5
Smallest element is: 5
Array elements का योग
array में रखी सभी values जोड़ता है।
import java.util.Scanner;
public class ArraySum {
public static void main(String[] args) {
int i,sum=0;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
}
for(i=0;i<5;i++)
{
sum=sum+arr[i];
}
System.out.println("Sum is "+sum);
}
}
Output:
Enter 5 numbers
10 20 30 40 50
Sum is 150
Array elements का औसत
योग निकालकर गिनती से भाग देता है।
import java.util.Scanner;
public class ArrayAvg {
public static void main(String[] args) {
int i,sum=0;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
sum=sum+arr[i];
}
System.out.println("Average is "+(sum/5.0));
}
}
Output:
Enter 5 numbers
10 20 30 40 50
Average is 30.0
Array में element खोजना
linear search जो हर element को मेल के लिए जाँचता है।
import java.util.Scanner;
public class ArraySearch {
public static void main(String[] args) {
int i,key,f=0;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
}
System.out.println("Enter number to search");
key=obj1.nextInt();
for(i=0;i<5;i++)
{
if(arr[i]==key)
{
f=1;
break;
}
}
if(f==1)
System.out.println("Element found");
else
System.out.println("Element not found");
}
}
Output:
Enter 5 numbers
10 20 30 40 50
Enter number to search
30
Element found
Array उल्टा करना
array के elements आख़िरी से पहले तक print करता है।
import java.util.Scanner;
public class ArrayReverse {
public static void main(String[] args) {
int i;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
}
System.out.println("Reversed array:");
for(i=4;i>=0;i--)
{
System.out.println(arr[i]);
}
}
}
Output:
Enter 5 numbers
10 20 30 40 50
Reversed array:
50
40
30
20
10
Array में even-odd गिनना
गिनता है कितने elements even हैं और कितने odd।
import java.util.Scanner;
public class ArrayEvenOdd {
public static void main(String[] args) {
int i,ec=0,oc=0;
int [] arr = new int [5];
Scanner obj1=new Scanner(System.in);
System.out.println("Enter 5 numbers");
for(i=0;i<5;i++)
{
arr[i]=obj1.nextInt();
if(arr[i]%2==0)
ec++;
else
oc++;
}
System.out.println("Even count: "+ec);
System.out.println("Odd count: "+oc);
}
}
Output:
Enter 5 numbers
10 15 20 25 30
Even count: 3
Odd count: 2
String programs
String को upper case में
built-in toUpperCase() method इस्तेमाल करता है।
import java.util.Scanner;
public class UpperCase {
public static void main(String[] args) {
String myname;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Name in lower case");
myname=obj1.nextLine();
System.out.println("Upper case string is :"+myname.toUpperCase());
}
}
Output:
Enter a Name in lower case
alpine
Upper case string is :ALPINE
String को lower case में
built-in toLowerCase() method इस्तेमाल करता है।
import java.util.Scanner;
public class LowerCase {
public static void main(String[] args) {
String myname;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Name in UPPER case");
myname=obj1.nextLine();
System.out.println("Lower case string is :"+myname.toLowerCase());
}
}
Output:
Enter a Name in UPPER case
ALPINE
Lower case string is :alpine
Vowels और consonants गिनना
हर अक्षर से गुज़रकर vowels और consonants गिनता है।
import java.util.Scanner;
public class VowelCount {
public static void main(String[] args) {
int count_v = 0, count_c = 0;
String mystring;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a String");
mystring=obj1.nextLine();
mystring = mystring.toLowerCase();
for(int i = 0; i < mystring.length(); i++) {
if(mystring.charAt(i) == 'a' || mystring.charAt(i) == 'e' ||
mystring.charAt(i) == 'i' || mystring.charAt(i) == 'o' || mystring.charAt(i) == 'u')
count_v=count_v+1 ;
else if(mystring.charAt(i) >= 'a' && mystring.charAt(i)<='z')
count_c=count_c+1;
}
System.out.println("Number of vowels: " + count_v);
System.out.println("Number of consonants: " + count_c);
}
}
Output:
Enter a String
alpine public school
Number of vowels: 7
Number of consonants: 11
String की लंबाई
अक्षर गिनने के लिए length() method इस्तेमाल करता है।
import java.util.Scanner;
public class StringLength {
public static void main(String[] args) {
String s;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a String");
s=obj1.nextLine();
System.out.println("Length is "+s.length());
}
}
Output:
Enter a String
alpine
Length is 6
String उल्टा करना
आख़िर से एक-एक अक्षर लेकर उल्टा text बनाता है।
import java.util.Scanner;
public class StringReverse {
public static void main(String[] args) {
String s,rev="";
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a String");
s=obj1.nextLine();
for(int i=s.length()-1;i>=0;i--)
{
rev=rev+s.charAt(i);
}
System.out.println("Reverse is "+rev);
}
}
Output:
Enter a String
alpine
Reverse is enipla
Palindrome string जाँचें
string उल्टा करके original से तुलना करता है।
import java.util.Scanner;
public class Palindrome {
public static void main(String[] args) {
String s,rev="";
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a String");
s=obj1.nextLine();
for(int i=s.length()-1;i>=0;i--)
{
rev=rev+s.charAt(i);
}
if(s.equals(rev))
System.out.println("It is a Palindrome");
else
System.out.println("Not a Palindrome");
}
}
Output:
Enter a String
madam
It is a Palindrome
वाक्य में शब्द गिनना
वाक्य को space से बाँटकर हिस्से गिनता है।
import java.util.Scanner;
public class WordCount {
public static void main(String[] args) {
String s;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Sentence");
s=obj1.nextLine();
String[] words = s.split(" ");
System.out.println("Number of words: "+words.length);
}
}
Output:
Enter a Sentence
alpine public school
Number of words: 3
Method और Class programs
Method से circle का area
area formula को अपने method में रखता है जो value लौटाता है।
import java.util.Scanner;
public class CircleArea {
public static double area_circle(double r)
{
double area;
area=3.14*r*r;
return(area);
}
public static void main(String[] args) {
double r,area;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Radius");
r=obj1.nextDouble();
area=area_circle(r);
System.out.println("Area of Circle is :"+area);
}
}
Output:
Enter Radius
4
Area of Circle is :50.24
Rectangle class और area method
एक अलग class method के साथ बनाकर object से call करता है।
class Rectangle{
int length;
int width;
int area_calculate(int l, int w){
int area;
area=l*w;
return area;
}
}
public class RectangleArea {
public static void main(String args[]){
int area;
Rectangle r1=new Rectangle();
area=r1.area_calculate(11,5);
System.out.println("Area is : "+area);
}
}
Output:
Area is : 55
Method से दो संख्याओं का योग
एक method जो दो संख्याएँ लेकर उनका योग लौटाता है।
import java.util.Scanner;
public class SumMethod {
public static int add(int a, int b)
{
return a+b;
}
public static void main(String[] args) {
int x,y;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter two numbers");
x=obj1.nextInt();
y=obj1.nextInt();
System.out.println("Sum is "+add(x,y));
}
}
Output:
Enter two numbers
10 20
Sum is 30
Method से factorial
factorial logic को एक return करने वाले method में अलग करता है।
import java.util.Scanner;
public class FactMethod {
public static int fact(int n)
{
int f=1,i;
for(i=n;i>=1;i--)
f=f*i;
return f;
}
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
System.out.println("Factorial is "+fact(n));
}
}
Output:
Enter a Number
5
Factorial is 120
Student class विवरण के साथ
fields और उन्हें दिखाने वाले method के साथ class बनाता है।
class Student{
int roll;
String name;
void show(){
System.out.println("Roll: "+roll);
System.out.println("Name: "+name);
}
}
public class StudentDemo {
public static void main(String[] args) {
Student s1=new Student();
s1.roll=1;
s1.name="Aarav";
s1.show();
}
}
Output:
Roll: 1
Name: Aarav
Method से साधारण ब्याज
एक method p, r और t से साधारण ब्याज निकालता है।
import java.util.Scanner;
public class SimpleInterest {
public static double si(double p, double r, double t)
{
return (p*r*t)/100;
}
public static void main(String[] args) {
double p,r,t;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Principal, Rate, Time");
p=obj1.nextDouble();
r=obj1.nextDouble();
t=obj1.nextDouble();
System.out.println("Simple Interest is "+si(p,r,t));
}
}
Output:
Enter Principal, Rate, Time
1000 5 2
Simple Interest is 100.0
Method से even जाँचना
एक method even संख्या के लिए true या false लौटाता है।
import java.util.Scanner;
public class EvenMethod {
public static boolean isEven(int n)
{
if(n%2==0)
return true;
else
return false;
}
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a Number");
n=obj1.nextInt();
if(isEven(n))
System.out.println("Even");
else
System.out.println("Odd");
}
}
Output:
Enter a Number
8
Even
switch case programs
संख्या से day name
1 से 7 day number पढ़कर उसका नाम print करता है।
import java.util.Scanner;
public class DayName {
public static void main(String[] args) {
int day;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Day Number");
day=obj1.nextInt();
switch(day)
{
case 1: System.out.println("Sunday"); break;
case 2: System.out.println("Monday"); break;
case 3: System.out.println("Tuesday"); break;
case 4: System.out.println("Wednesday"); break;
case 5: System.out.println("Thursday"); break;
case 6: System.out.println("Friday"); break;
case 7: System.out.println("Saturday"); break;
default: System.out.println("Invalid Day Number");
}
}
}
Output:
Enter Day Number
5
Thursday
सरल calculator
operator के चिह्न पर switch लगाकर operation चुनता है।
import java.util.Scanner;
public class Calculator {
public static void main(String[] args) {
int a,b;
char op;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter two numbers");
a=obj1.nextInt();
b=obj1.nextInt();
System.out.println("Enter operator (+ - * /)");
op=obj1.next().charAt(0);
switch(op)
{
case '+': System.out.println(a+b); break;
case '-': System.out.println(a-b); break;
case '*': System.out.println(a*b); break;
case '/': System.out.println(a/b); break;
default: System.out.println("Invalid operator");
}
}
}
Output:
Enter two numbers
10 5
Enter operator (+ - * /)
+
15
संख्या से महीने का नाम
1 से 12 संख्या के लिए महीने का नाम print करता है।
import java.util.Scanner;
public class MonthName {
public static void main(String[] args) {
int m;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Month Number");
m=obj1.nextInt();
switch(m)
{
case 1: System.out.println("January"); break;
case 2: System.out.println("February"); break;
case 3: System.out.println("March"); break;
case 4: System.out.println("April"); break;
case 5: System.out.println("May"); break;
case 6: System.out.println("June"); break;
default: System.out.println("Enter 1 to 6");
}
}
}
Output:
Enter Month Number
3
March
Vowel या consonant
switch से जाँचता है कि अक्षर vowel है या नहीं।
import java.util.Scanner;
public class VowelSwitch {
public static void main(String[] args) {
char ch;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a character");
ch=obj1.next().charAt(0);
switch(ch)
{
case 'a':
case 'e':
case 'i':
case 'o':
case 'u': System.out.println("Vowel"); break;
default: System.out.println("Consonant");
}
}
}
Output:
Enter a character
e
Vowel
choice से grade
switch से grade अक्षर के आधार पर संदेश print करता है।
import java.util.Scanner;
public class GradeSwitch {
public static void main(String[] args) {
char g;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Grade (A B C)");
g=obj1.next().charAt(0);
switch(g)
{
case 'A': System.out.println("Excellent"); break;
case 'B': System.out.println("Good"); break;
case 'C': System.out.println("Average"); break;
default: System.out.println("Invalid Grade");
}
}
}
Output:
Enter Grade (A B C)
A
Excellent
अंकगणित menu
choices के लिए switch वाला menu-driven program।
import java.util.Scanner;
public class MenuSwitch {
public static void main(String[] args) {
int choice,a=12,b=4;
Scanner obj1=new Scanner(System.in);
System.out.println("1.Add 2.Sub 3.Mul");
System.out.println("Enter choice");
choice=obj1.nextInt();
switch(choice)
{
case 1: System.out.println("Sum = "+(a+b)); break;
case 2: System.out.println("Diff = "+(a-b)); break;
case 3: System.out.println("Product = "+(a*b)); break;
default: System.out.println("Wrong choice");
}
}
}
Output:
1.Add 2.Sub 3.Mul
Enter choice
1
Sum = 16
संख्या शब्दों में (1-5)
switch से छोटी संख्या का शब्द रूप print करता है।
import java.util.Scanner;
public class NumberWords {
public static void main(String[] args) {
int n;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter a number (1-5)");
n=obj1.nextInt();
switch(n)
{
case 1: System.out.println("One"); break;
case 2: System.out.println("Two"); break;
case 3: System.out.println("Three"); break;
case 4: System.out.println("Four"); break;
case 5: System.out.println("Five"); break;
default: System.out.println("Enter 1 to 5");
}
}
}
Output:
Enter a number (1-5)
3
Three
Exception handling programs
Divide by zero exception
try-catch, ArithmeticException संभालता है ताकि program crash न हो।
import java.util.Scanner;
public class DivZero {
public static void main(String[] args) {
int divi,divis,sum;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter Dividend Number");
divi=obj1.nextInt();
System.out.println("Enter Divisor Number");
divis=obj1.nextInt();
try
{
System.out.println(divi/divis);
}
catch (ArithmeticException e)
{
System.out.println("Divided by zero operation cannot possible");
}
sum=divi+divis;
System.out.println("sum is :"+sum);
}
}
Output:
Enter Dividend Number
34
Enter Divisor Number
0
Divided by zero operation cannot possible
sum is :34
Array index out of bounds
ग़लत index पर ArrayIndexOutOfBoundsException पकड़ता है।
public class ArrayIndex {
public static void main(String[] args) {
int [] arr = {10,20,30};
try
{
System.out.println(arr[5]);
}
catch (ArrayIndexOutOfBoundsException e)
{
System.out.println("Invalid array index");
}
}
}
Output:
Invalid array index
Number format exception
जब non-number string parse हो तो error पकड़ता है।
public class NumFormat {
public static void main(String[] args) {
try
{
int n=Integer.parseInt("abc");
System.out.println(n);
}
catch (NumberFormatException e)
{
System.out.println("Not a valid number");
}
}
}
Output:
Not a valid number
Null pointer exception
null reference इस्तेमाल करने पर error पकड़ता है।
public class NullDemo {
public static void main(String[] args) {
String s=null;
try
{
System.out.println(s.length());
}
catch (NullPointerException e)
{
System.out.println("Null value cannot be used");
}
}
}
Output:
Null value cannot be used
try-catch-finally
दिखाता है कि finally block हमेशा चलता है।
public class FinallyDemo {
public static void main(String[] args) {
try
{
int x=10/0;
}
catch (ArithmeticException e)
{
System.out.println("Cannot divide by zero");
}
finally
{
System.out.println("This always runs");
}
}
}
Output:
Cannot divide by zero
This always runs
अपना message throw करना
throw से एक message के साथ exception उठाता है।
import java.util.Scanner;
public class ThrowDemo {
public static void main(String[] args) {
int age;
Scanner obj1=new Scanner(System.in);
System.out.println("Enter age");
age=obj1.nextInt();
try
{
if(age<18)
throw new ArithmeticException("Not an adult");
System.out.println("You are an adult");
}
catch (ArithmeticException e)
{
System.out.println("Error: "+e.getMessage());
}
}
}
Output:
Enter age
15
Error: Not an adult
कई catch blocks
अलग catch blocks से दो अलग exceptions संभालता है।
public class MultiCatch {
public static void main(String[] args) {
try
{
int [] arr = new int[3];
arr[5]=10/0;
}
catch (ArithmeticException e)
{
System.out.println("Arithmetic problem");
}
catch (ArrayIndexOutOfBoundsException e)
{
System.out.println("Array problem");
}
}
}
Output:
Arithmetic problem
सारांश
- Programs topic के हिसाब से समूह में हैं, हर समूह में 7-8, केंद्रित अभ्यास के लिए।
- हर program में असली code और output है, standard practical-file शैली में।
- built-in Live Code Editor कोई भी program आपके browser में चलाता है - install की ज़रूरत नहीं।
- Scanner से input पढ़ने वाले programs के लिए STDIN box इस्तेमाल कीजिए।
पहले बुनियाद बनाइए Introduction to Java से, input सीखिए User Input using Scanner में, या और आज़माइए 68 Java Practice Programs में।
अक्सर पूछे जाने वाले प्रश्न (FAQ)
क्या मैं ये Java programs बिना कुछ install किए online चला सकता हूँ?
हाँ। इस page में एक built-in Live Code Editor है। programs उसमें अपने-आप load हो जाते हैं - dropdown से कोई चुनिए या ख़ुद type कीजिए और Run दबाइए, यह आपके browser में compile और run होता है, तो practise के लिए JDK या NetBeans install करने की ज़रूरत नहीं।
Programs किस तरह व्यवस्थित हैं?
ये topic के हिसाब से समूह में हैं - if-else conditions, loops, arrays, strings, methods और classes, switch case, और exception handling। हर topic में सात-आठ छोटे programs हैं, ताकि आप एक concept पूरा अभ्यास करके अगले पर जाएँ।
क्या इन programs के लिए input देना पड़ता है?
कई programs Scanner class से input पढ़ते हैं। उन्हें editor में चलाते समय STDIN या input box में input type कीजिए, और program उसे वैसे ही पढ़ेगा जैसे NetBeans में। Scanner बिना वाले programs सीधे चलते हैं।
ये programs किस class के लिए ठीक हैं?
ये standard Class 12 Information Technology (802) practical file शैली का पालन करते हैं, पर core Java सीखने वाले किसी भी शुरुआती के लिए ठीक हैं, जिसमें BCA, diploma और first-year college के students शामिल हैं।
Class के नाम Practical1, Practical2 से अलग क्यों हैं?
यहाँ हर program का एक अर्थपूर्ण class नाम है जैसे BigThree या Factorial, जो numbered नाम से ज़्यादा साफ़ है। logic और code flow बिल्कुल वही सरल शैली है जो practical file में इस्तेमाल होती है।