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✅ Practice + Quiz  ·  Lesson 27

68 Java Practice Programs

Written and reviewed by · Senior IT Faculty · 15+ years’ experience

Easy Formula Programs with User Input

Start with these programs first. Every program takes values from the user, applies one clear formula and prints the result. Copy the code, change the input and practise.
1. Add two numbers entered by the user2. Area of a rectangle3. Area of a circle4. Metres to kilometres5. Kilometres to metres6. Rupees to paise7. Paise to rupees8. Celsius to Fahrenheit9. Fahrenheit to Celsius10. Simple interest11. Compound interest12. Area of a triangle13. Perimeter of a rectangle14. Circumference of a circle15. Total and percentage of five subjects16. GST amount17. Body mass index (BMI)18. Square and cube of a number

1. Add two numbers entered by the user

Reads two numbers and displays their sum.

Formula: Sum = first number + second number
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter first number: ");
        double a = input.nextDouble();
        System.out.print("Enter second number: ");
        double b = input.nextDouble();
        double result = a + b;
        System.out.println("Sum = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter first number: 25
Enter second number: 17
Sum = 42

2. Area of a rectangle

Uses length and breadth to calculate the rectangular area.

Formula: Area = length x breadth
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter length: ");
        double length = input.nextDouble();
        System.out.print("Enter breadth: ");
        double breadth = input.nextDouble();
        double result = length * breadth;
        System.out.println("Area = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter length: 12
Enter breadth: 5
Area = 60

3. Area of a circle

Reads the radius and calculates the area of a circle.

Formula: Area = pi x radius x radius
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter radius: ");
        double radius = input.nextDouble();
        double result = 3.14159 * radius * radius;
        System.out.println("Area = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter radius: 7
Area = 153.938

4. Metres to kilometres

Converts a distance from metres to kilometres.

Formula: Kilometres = metres / 1000
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter distance in metres: ");
        double metres = input.nextDouble();
        double result = metres / 1000;
        System.out.println("Kilometres = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter distance in metres: 2500
Kilometres = 2.5

5. Kilometres to metres

Converts a distance from kilometres to metres.

Formula: Metres = kilometres x 1000
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter distance in kilometres: ");
        double kilometres = input.nextDouble();
        double result = kilometres * 1000;
        System.out.println("Metres = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter distance in kilometres: 3.5
Metres = 3500

6. Rupees to paise

Converts an amount in rupees into paise.

Formula: Paise = rupees x 100
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter amount in rupees: ");
        double rupees = input.nextDouble();
        double result = rupees * 100;
        System.out.println("Paise = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter amount in rupees: 125.50
Paise = 12550

7. Paise to rupees

Converts an amount in paise into rupees.

Formula: Rupees = paise / 100
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter amount in paise: ");
        double paise = input.nextDouble();
        double result = paise / 100;
        System.out.println("Rupees = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter amount in paise: 8750
Rupees = 87.5

8. Celsius to Fahrenheit

Converts a temperature from Celsius to Fahrenheit.

Formula: F = (C x 9 / 5) + 32
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter temperature in Celsius: ");
        double celsius = input.nextDouble();
        double result = (celsius * 9 / 5) + 32;
        System.out.println("Fahrenheit = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter temperature in Celsius: 30
Fahrenheit = 86

9. Fahrenheit to Celsius

Converts a temperature from Fahrenheit to Celsius.

Formula: C = (F - 32) x 5 / 9
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter temperature in Fahrenheit: ");
        double fahrenheit = input.nextDouble();
        double result = (fahrenheit - 32) * 5 / 9;
        System.out.println("Celsius = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter temperature in Fahrenheit: 98.6
Celsius = 37

10. Simple interest

Calculates simple interest from principal, rate and time.

Formula: SI = principal x rate x time / 100
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter principal: ");
        double principal = input.nextDouble();
        System.out.print("Enter annual rate: ");
        double rate = input.nextDouble();
        System.out.print("Enter time in years: ");
        double time = input.nextDouble();
        double result = principal * rate * time / 100;
        System.out.println("Simple interest = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter principal: 5000
Enter annual rate: 6
Enter time in years: 2
Simple interest = 600

11. Compound interest

Calculates annually compounded interest.

Formula: CI = P(1 + R/100)^T - P
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter principal: ");
        double principal = input.nextDouble();
        System.out.print("Enter annual rate: ");
        double rate = input.nextDouble();
        System.out.print("Enter time in years: ");
        double time = input.nextDouble();
        double result = principal * Math.pow(1 + rate / 100, time) - principal;
        System.out.println("Compound interest = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter principal: 10000
Enter annual rate: 10
Enter time in years: 2
Compound interest = 2100

12. Area of a triangle

Uses base and height to calculate the triangle area.

Formula: Area = base x height / 2
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter base: ");
        double base = input.nextDouble();
        System.out.print("Enter height: ");
        double height = input.nextDouble();
        double result = base * height / 2;
        System.out.println("Area = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter base: 10
Enter height: 8
Area = 40

13. Perimeter of a rectangle

Adds all four sides of a rectangle.

Formula: Perimeter = 2 x (length + breadth)
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter length: ");
        double length = input.nextDouble();
        System.out.print("Enter breadth: ");
        double breadth = input.nextDouble();
        double result = 2 * (length + breadth);
        System.out.println("Perimeter = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter length: 12
Enter breadth: 5
Perimeter = 34

14. Circumference of a circle

Calculates the distance around a circle from its radius.

Formula: Circumference = 2 x pi x radius
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter radius: ");
        double radius = input.nextDouble();
        double result = 2 * 3.14159 * radius;
        System.out.println("Circumference = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter radius: 7
Circumference = 43.9823

15. Total and percentage of five subjects

Reads five marks, then calculates total and percentage.

Formula: Percentage = total marks / 5
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter marks in subject 1: ");
        double m1 = input.nextDouble();
        System.out.print("Enter marks in subject 2: ");
        double m2 = input.nextDouble();
        System.out.print("Enter marks in subject 3: ");
        double m3 = input.nextDouble();
        System.out.print("Enter marks in subject 4: ");
        double m4 = input.nextDouble();
        System.out.print("Enter marks in subject 5: ");
        double m5 = input.nextDouble();
        double result = (m1 + m2 + m3 + m4 + m5) / 5;
        System.out.println("Total = " + (m1+m2+m3+m4+m5));
        System.out.println("Percentage = " + result);
        input.close();
    }
}
Sample Input and Output:
Marks: 80 75 90 85 70
Total = 400
Percentage = 80

16. GST amount

Calculates GST and the final bill amount.

Formula: GST = amount x rate / 100
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter amount: ");
        double amount = input.nextDouble();
        System.out.print("Enter GST rate: ");
        double gstRate = input.nextDouble();
        double result = amount * gstRate / 100;
        System.out.println("GST = " + result);
        System.out.println("Final amount = " + (amount+result));
        input.close();
    }
}
Sample Input and Output:
Enter amount: 2000
Enter GST rate: 18
GST = 360
Final amount = 2360

17. Body mass index (BMI)

Calculates BMI from weight in kilograms and height in metres.

Formula: BMI = weight / (height x height)
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter weight in kg: ");
        double weight = input.nextDouble();
        System.out.print("Enter height in metres: ");
        double height = input.nextDouble();
        double result = weight / (height * height);
        System.out.println("BMI = " + result);
        input.close();
    }
}
Sample Input and Output:
Enter weight in kg: 72
Enter height in metres: 1.8
BMI = 22.2222

18. Square and cube of a number

Reads one number and prints both its square and cube.

Formula: Square = n x n; Cube = n x n x n
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter a number: ");
        double number = input.nextDouble();
        double result = number * number;
        System.out.println("Square = " + result);
        System.out.println("Cube = " + (number*number*number));
        input.close();
    }
}
Sample Input and Output:
Enter a number: 5
Square = 25
Cube = 125

About

A collection of 50 important Java practice programs covering calculations, decisions, loops, patterns and arrays. Each is a complete program with expected output.

Basic Calculation Programs

1. Add two numbers
public class Main {
    public static void main(String[] args) {
        int a=5,b=3;
        System.out.println("Sum = "+(a+b));  // 8
    }
}
2. Subtract two numbers
public class Main {
    public static void main(String[] args) {
        int a=10,b=4;
        System.out.println("Diff = "+(a-b));  // 6
    }
}
3. Multiply two numbers
public class Main {
    public static void main(String[] args) {
        int a=6,b=7;
        System.out.println("Product = "+(a*b));  // 42
    }
}
4. Divide two numbers
public class Main {
    public static void main(String[] args) {
        double a=10,b=4;
        System.out.println("Result = "+(a/b));  // 2.5
    }
}
5. Find remainder
public class Main {
    public static void main(String[] args) {
        int a=17,b=5;
        System.out.println("Remainder = "+(a%b));  // 2
    }
}
6. Area of rectangle
public class Main {
    public static void main(String[] args) {
        int l=8,w=3;
        System.out.println("Area = "+(l*w));  // 24
    }
}
7. Area of circle
public class Main {
    public static void main(String[] args) {
        double r=7;
        System.out.println("Area = "+(3.14*r*r));  // 153.86
    }
}
8. Simple interest
public class Main {
    public static void main(String[] args) {
        double p=1000,r=5,t=2;
        System.out.println("SI = "+((p*r*t)/100));  // 100.0
    }
}
9. Average of three numbers
public class Main {
    public static void main(String[] args) {
        int a=10,b=20,c=30;
        System.out.println("Avg = "+((a+b+c)/3.0));  // 20.0
    }
}
10. Swap two numbers
public class Main {
    public static void main(String[] args) {
        int a=5,b=9,t;
        t=a;a=b;b=t;
        System.out.println("a="+a+" b="+b);  // a=9 b=5
    }
}

If-Else and If-Else-If Programs

1. Check even or odd
public class Main {
    public static void main(String[] args) {
        int n=7;
        if(n%2==0) System.out.println("Even");
        else System.out.println("Odd");  // Odd
    }
}
2. Largest of two numbers
public class Main {
    public static void main(String[] args) {
        int a=12,b=20;
        System.out.println(a>b?a:b);  // 20
    }
}
3. Largest of three numbers
public class Main {
    public static void main(String[] args) {
        int a=5,b=9,c=3;
        if(a>=b&&a>=c)System.out.println(a);
        else if(b>=c)System.out.println(b);
        else System.out.println(c);  // 9
    }
}
4. Positive, negative or zero
public class Main {
    public static void main(String[] args) {
        int n=-4;
        if(n>0)System.out.println("Positive");
        else if(n<0)System.out.println("Negative");
        else System.out.println("Zero");  // Negative
    }
}
5. Check pass or fail
public class Main {
    public static void main(String[] args) {
        int marks=45;
        if(marks>=33)System.out.println("Pass");
        else System.out.println("Fail");  // Pass
    }
}
6. Grade using if-else-if
public class Main {
    public static void main(String[] args) {
        int m=82;
        if(m>=90)System.out.println("A+");
        else if(m>=75)System.out.println("A");
        else if(m>=33)System.out.println("Pass");
        else System.out.println("Fail");  // A
    }
}
7. Check leap year
public class Main {
    public static void main(String[] args) {
        int y=2024;
        if((y%4==0&&y%100!=0)||y%400==0)System.out.println("Leap");
        else System.out.println("Not Leap");  // Leap
    }
}
8. Check vowel or consonant
public class Main {
    public static void main(String[] args) {
        char ch='e';
        if(ch=='a'||ch=='e'||ch=='i'||ch=='o'||ch=='u')System.out.println("Vowel");
        else System.out.println("Consonant");  // Vowel
    }
}
9. Divisible by 5 and 11
public class Main {
    public static void main(String[] args) {
        int n=55;
        if(n%5==0&&n%11==0)System.out.println("Yes");
        else System.out.println("No");  // Yes
    }
}
10. Largest using ternary
public class Main {
    public static void main(String[] args) {
        int a=7,b=4;
        System.out.println(a>b?a:b);  // 7
    }
}

Loop Programs

1. Print 1 to 10
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=10;i++) System.out.print(i+" ");  // 1..10
    }
}
2. Sum of first N numbers
public class Main {
    public static void main(String[] args) {
        int n=5,sum=0;
        for(int i=1;i<=n;i++) sum+=i;
        System.out.println("Sum = "+sum);  // 15
    }
}
3. Factorial
public class Main {
    public static void main(String[] args) {
        int n=5,f=1;
        for(int i=1;i<=n;i++) f*=i;
        System.out.println("Factorial = "+f);  // 120
    }
}
4. Multiplication table
public class Main {
    public static void main(String[] args) {
        int n=5;
        for(int i=1;i<=10;i++) System.out.println(n+" x "+i+" = "+(n*i));
    }
}
5. Print even numbers 1-20
public class Main {
    public static void main(String[] args) {
        for(int i=2;i<=20;i+=2) System.out.print(i+" ");  // 2..20
    }
}
6. Reverse a number
public class Main {
    public static void main(String[] args) {
        int n=1234,rev=0;
        while(n>0){rev=rev*10+n%10;n/=10;}
        System.out.println(rev);  // 4321
    }
}
7. Sum of digits
public class Main {
    public static void main(String[] args) {
        int n=123,s=0;
        while(n>0){s+=n%10;n/=10;}
        System.out.println("Sum = "+s);  // 6
    }
}
8. Count digits
public class Main {
    public static void main(String[] args) {
        int n=98765,c=0;
        while(n>0){c++;n/=10;}
        System.out.println("Digits = "+c);  // 5
    }
}
9. Check prime
public class Main {
    public static void main(String[] args) {
        int n=13;boolean p=true;
        for(int i=2;i<n;i++) if(n%i==0) p=false;
        System.out.println(p?"Prime":"Not Prime");  // Prime
    }
}
10. Fibonacci series
public class Main {
    public static void main(String[] args) {
        int a=0,b=1,c;
        for(int i=0;i<7;i++){System.out.print(a+" ");c=a+b;a=b;b=c;}  // 0 1 1 2 3 5 8
    }
}

Pattern Programs

1. Square of stars
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=4;i++){for(int j=1;j<=4;j++)System.out.print("* ");System.out.println();}
    }
}
2. Right triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=5;i++){for(int j=1;j<=i;j++)System.out.print("* ");System.out.println();}
    }
}
3. Inverted triangle
public class Main {
    public static void main(String[] args) {
        for(int i=5;i>=1;i--){for(int j=1;j<=i;j++)System.out.print("* ");System.out.println();}
    }
}
4. Number triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=5;i++){for(int j=1;j<=i;j++)System.out.print(j+" ");System.out.println();}
    }
}
5. Repeated number triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=5;i++){for(int j=1;j<=i;j++)System.out.print(i+" ");System.out.println();}
    }
}
6. Right-aligned triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=4;i++){for(int j=i;j<4;j++)System.out.print("  ");for(int k=1;k<=i;k++)System.out.print("* ");System.out.println();}
    }
}
7. Pyramid of stars
public class Main {
    public static void main(String[] args) {
        int n=4;
        for(int i=1;i<=n;i++){for(int j=i;j<n;j++)System.out.print(" ");for(int k=1;k<=2*i-1;k++)System.out.print("*");System.out.println();}
    }
}
8. Alphabet triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=5;i++){for(char c='A';c<'A'+i;c++)System.out.print(c+" ");System.out.println();}
    }
}
9. Diamond pattern
public class Main {
    public static void main(String[] args) {
        int n=3;
        for(int i=1;i<=n;i++){for(int j=i;j<n;j++)System.out.print(" ");for(int k=1;k<=2*i-1;k++)System.out.print("*");System.out.println();}
        for(int i=n-1;i>=1;i--){for(int j=n;j>i;j--)System.out.print(" ");for(int k=1;k<=2*i-1;k++)System.out.print("*");System.out.println();}
    }
}
10. Hollow square
public class Main {
    public static void main(String[] args) {
        int n=4;
        for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){if(i==1||i==n||j==1||j==n)System.out.print("* ");else System.out.print("  ");}System.out.println();}
    }
}

Array Programs

1. Sum of array
public class Main {
    public static void main(String[] args) {
        int[] a={10,20,30,40};int sum=0;
        for(int x:a) sum+=x;
        System.out.println("Sum = "+sum);  // 100
    }
}
2. Largest in array
public class Main {
    public static void main(String[] args) {
        int[] a={3,7,2,9,4};int mx=a[0];
        for(int x:a) if(x>mx) mx=x;
        System.out.println("Max = "+mx);  // 9
    }
}
3. Smallest in array
public class Main {
    public static void main(String[] args) {
        int[] a={3,7,2,9,4};int mn=a[0];
        for(int x:a) if(x<mn) mn=x;
        System.out.println("Min = "+mn);  // 2
    }
}
4. Average of array
public class Main {
    public static void main(String[] args) {
        int[] a={10,20,30};int s=0;
        for(int x:a) s+=x;
        System.out.println("Avg = "+(s/3.0));  // 20.0
    }
}
5. Reverse array
public class Main {
    public static void main(String[] args) {
        int[] a={1,2,3,4,5};
        for(int i=a.length-1;i>=0;i--) System.out.print(a[i]+" ");  // 5 4 3 2 1
    }
}
6. Count even numbers
public class Main {
    public static void main(String[] args) {
        int[] a={1,2,3,4,5,6};int c=0;
        for(int x:a) if(x%2==0) c++;
        System.out.println("Even = "+c);  // 3
    }
}
7. Linear search
public class Main {
    public static void main(String[] args) {
        int[] a={5,8,12,3};int key=12,pos=-1;
        for(int i=0;i<a.length;i++) if(a[i]==key) pos=i;
        System.out.println("Found at "+pos);  // 2
    }
}
8. Copy array
public class Main {
    public static void main(String[] args) {
        int[] a={1,2,3};int[] b=new int[3];
        for(int i=0;i<3;i++) b[i]=a[i];
        System.out.println(b[0]+""+b[1]+b[2]);  // 123
    }
}
9. Sort ascending
public class Main {
    public static void main(String[] args) {
        int[] a={5,2,8,1};int n=a.length;
        for(int i=0;i<n;i++)for(int j=0;j<n-i-1;j++)if(a[j]>a[j+1]){int t=a[j];a[j]=a[j+1];a[j+1]=t;}
        for(int x:a) System.out.print(x+" ");  // 1 2 5 8
    }
}
10. Count positive/negative
public class Main {
    public static void main(String[] args) {
        int[] a={-1,2,-3,4,5};int p=0,n=0;
        for(int x:a){if(x>=0)p++;else n++;}
        System.out.println("Pos="+p+" Neg="+n);  // Pos=3 Neg=2
    }
}

User Input वाले आसान Formula Programs

इन programs को सबसे पहले करें। हर program user से value लेता है, एक सीधा formula लगाता है और result दिखाता है। Code को copy करके input बदलकर अभ्यास करें।
1. User द्वारा दिए गए दो numbers जोड़ें2. Rectangle का area3. Circle का area4. Metres को kilometres में बदलें5. Kilometres को metres में बदलें6. Rupees को paise में बदलें7. Paise को rupees में बदलें8. Celsius को Fahrenheit में बदलें9. Fahrenheit को Celsius में बदलें10. Simple interest निकालें11. Compound interest निकालें12. Triangle का area13. Rectangle का perimeter14. Circle की circumference15. Five subjects का total और percentage16. GST amount निकालें17. Body mass index (BMI)18. Number का square और cube

1. User द्वारा दिए गए दो numbers जोड़ें

दो numbers input लेकर उनका sum दिखाता है।

Formula: Sum = first number + second number
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter first number: ");
        double a = input.nextDouble();
        System.out.print("Enter second number: ");
        double b = input.nextDouble();
        double result = a + b;
        System.out.println("Sum = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter first number: 25
Enter second number: 17
Sum = 42

2. Rectangle का area

Length और breadth से rectangle का area निकालता है।

Formula: Area = length x breadth
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter length: ");
        double length = input.nextDouble();
        System.out.print("Enter breadth: ");
        double breadth = input.nextDouble();
        double result = length * breadth;
        System.out.println("Area = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter length: 12
Enter breadth: 5
Area = 60

3. Circle का area

Radius input लेकर circle का area निकालता है।

Formula: Area = pi x radius x radius
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter radius: ");
        double radius = input.nextDouble();
        double result = 3.14159 * radius * radius;
        System.out.println("Area = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter radius: 7
Area = 153.938

4. Metres को kilometres में बदलें

Distance को metres से kilometres में बदलता है।

Formula: Kilometres = metres / 1000
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter distance in metres: ");
        double metres = input.nextDouble();
        double result = metres / 1000;
        System.out.println("Kilometres = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter distance in metres: 2500
Kilometres = 2.5

5. Kilometres को metres में बदलें

Distance को kilometres से metres में बदलता है।

Formula: Metres = kilometres x 1000
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter distance in kilometres: ");
        double kilometres = input.nextDouble();
        double result = kilometres * 1000;
        System.out.println("Metres = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter distance in kilometres: 3.5
Metres = 3500

6. Rupees को paise में बदलें

Rupees की amount को paise में बदलता है।

Formula: Paise = rupees x 100
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter amount in rupees: ");
        double rupees = input.nextDouble();
        double result = rupees * 100;
        System.out.println("Paise = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter amount in rupees: 125.50
Paise = 12550

7. Paise को rupees में बदलें

Paise की amount को rupees में बदलता है।

Formula: Rupees = paise / 100
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter amount in paise: ");
        double paise = input.nextDouble();
        double result = paise / 100;
        System.out.println("Rupees = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter amount in paise: 8750
Rupees = 87.5

8. Celsius को Fahrenheit में बदलें

Temperature को Celsius से Fahrenheit में बदलता है।

Formula: F = (C x 9 / 5) + 32
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter temperature in Celsius: ");
        double celsius = input.nextDouble();
        double result = (celsius * 9 / 5) + 32;
        System.out.println("Fahrenheit = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter temperature in Celsius: 30
Fahrenheit = 86

9. Fahrenheit को Celsius में बदलें

Temperature को Fahrenheit से Celsius में बदलता है।

Formula: C = (F - 32) x 5 / 9
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter temperature in Fahrenheit: ");
        double fahrenheit = input.nextDouble();
        double result = (fahrenheit - 32) * 5 / 9;
        System.out.println("Celsius = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter temperature in Fahrenheit: 98.6
Celsius = 37

10. Simple interest निकालें

Principal, rate और time से simple interest निकालता है।

Formula: SI = principal x rate x time / 100
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter principal: ");
        double principal = input.nextDouble();
        System.out.print("Enter annual rate: ");
        double rate = input.nextDouble();
        System.out.print("Enter time in years: ");
        double time = input.nextDouble();
        double result = principal * rate * time / 100;
        System.out.println("Simple interest = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter principal: 5000
Enter annual rate: 6
Enter time in years: 2
Simple interest = 600

11. Compound interest निकालें

Annual compounding के अनुसार compound interest निकालता है।

Formula: CI = P(1 + R/100)^T - P
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter principal: ");
        double principal = input.nextDouble();
        System.out.print("Enter annual rate: ");
        double rate = input.nextDouble();
        System.out.print("Enter time in years: ");
        double time = input.nextDouble();
        double result = principal * Math.pow(1 + rate / 100, time) - principal;
        System.out.println("Compound interest = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter principal: 10000
Enter annual rate: 10
Enter time in years: 2
Compound interest = 2100

12. Triangle का area

Base और height से triangle का area निकालता है।

Formula: Area = base x height / 2
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter base: ");
        double base = input.nextDouble();
        System.out.print("Enter height: ");
        double height = input.nextDouble();
        double result = base * height / 2;
        System.out.println("Area = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter base: 10
Enter height: 8
Area = 40

13. Rectangle का perimeter

Rectangle की चारों sides का total निकालता है।

Formula: Perimeter = 2 x (length + breadth)
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter length: ");
        double length = input.nextDouble();
        System.out.print("Enter breadth: ");
        double breadth = input.nextDouble();
        double result = 2 * (length + breadth);
        System.out.println("Perimeter = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter length: 12
Enter breadth: 5
Perimeter = 34

14. Circle की circumference

Radius से circle के चारों ओर की दूरी निकालता है।

Formula: Circumference = 2 x pi x radius
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter radius: ");
        double radius = input.nextDouble();
        double result = 2 * 3.14159 * radius;
        System.out.println("Circumference = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter radius: 7
Circumference = 43.9823

15. Five subjects का total और percentage

पाँच subjects के marks लेकर total और percentage निकालता है।

Formula: Percentage = total marks / 5
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter marks in subject 1: ");
        double m1 = input.nextDouble();
        System.out.print("Enter marks in subject 2: ");
        double m2 = input.nextDouble();
        System.out.print("Enter marks in subject 3: ");
        double m3 = input.nextDouble();
        System.out.print("Enter marks in subject 4: ");
        double m4 = input.nextDouble();
        System.out.print("Enter marks in subject 5: ");
        double m5 = input.nextDouble();
        double result = (m1 + m2 + m3 + m4 + m5) / 5;
        System.out.println("Total = " + (m1+m2+m3+m4+m5));
        System.out.println("Percentage = " + result);
        input.close();
    }
}
Sample Input और Output:
Marks: 80 75 90 85 70
Total = 400
Percentage = 80

16. GST amount निकालें

Amount और GST rate से tax तथा final bill निकालता है।

Formula: GST = amount x rate / 100
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter amount: ");
        double amount = input.nextDouble();
        System.out.print("Enter GST rate: ");
        double gstRate = input.nextDouble();
        double result = amount * gstRate / 100;
        System.out.println("GST = " + result);
        System.out.println("Final amount = " + (amount+result));
        input.close();
    }
}
Sample Input और Output:
Enter amount: 2000
Enter GST rate: 18
GST = 360
Final amount = 2360

17. Body mass index (BMI)

Weight (kg) और height (metres) से BMI निकालता है।

Formula: BMI = weight / (height x height)
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter weight in kg: ");
        double weight = input.nextDouble();
        System.out.print("Enter height in metres: ");
        double height = input.nextDouble();
        double result = weight / (height * height);
        System.out.println("BMI = " + result);
        input.close();
    }
}
Sample Input और Output:
Enter weight in kg: 72
Enter height in metres: 1.8
BMI = 22.2222

18. Number का square और cube

एक number input लेकर उसका square और cube दिखाता है।

Formula: Square = n x n; Cube = n x n x n
JAVA
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter a number: ");
        double number = input.nextDouble();
        double result = number * number;
        System.out.println("Square = " + result);
        System.out.println("Cube = " + (number*number*number));
        input.close();
    }
}
Sample Input और Output:
Enter a number: 5
Square = 25
Cube = 125

परिचय

50 ज़रूरी Java practice programs — calculations, decisions, loops, patterns और arrays। हर एक पूरा program है expected output के साथ।

Basic Calculation Programs (गणना)

1. Add two numbers
public class Main {
    public static void main(String[] args) {
        int a=5,b=3;
        System.out.println("Sum = "+(a+b));  // 8
    }
}
2. Subtract two numbers
public class Main {
    public static void main(String[] args) {
        int a=10,b=4;
        System.out.println("Diff = "+(a-b));  // 6
    }
}
3. Multiply two numbers
public class Main {
    public static void main(String[] args) {
        int a=6,b=7;
        System.out.println("Product = "+(a*b));  // 42
    }
}
4. Divide two numbers
public class Main {
    public static void main(String[] args) {
        double a=10,b=4;
        System.out.println("Result = "+(a/b));  // 2.5
    }
}
5. Find remainder
public class Main {
    public static void main(String[] args) {
        int a=17,b=5;
        System.out.println("Remainder = "+(a%b));  // 2
    }
}
6. Area of rectangle
public class Main {
    public static void main(String[] args) {
        int l=8,w=3;
        System.out.println("Area = "+(l*w));  // 24
    }
}
7. Area of circle
public class Main {
    public static void main(String[] args) {
        double r=7;
        System.out.println("Area = "+(3.14*r*r));  // 153.86
    }
}
8. Simple interest
public class Main {
    public static void main(String[] args) {
        double p=1000,r=5,t=2;
        System.out.println("SI = "+((p*r*t)/100));  // 100.0
    }
}
9. Average of three numbers
public class Main {
    public static void main(String[] args) {
        int a=10,b=20,c=30;
        System.out.println("Avg = "+((a+b+c)/3.0));  // 20.0
    }
}
10. Swap two numbers
public class Main {
    public static void main(String[] args) {
        int a=5,b=9,t;
        t=a;a=b;b=t;
        System.out.println("a="+a+" b="+b);  // a=9 b=5
    }
}

If-Else और If-Else-If Programs

1. Check even or odd
public class Main {
    public static void main(String[] args) {
        int n=7;
        if(n%2==0) System.out.println("Even");
        else System.out.println("Odd");  // Odd
    }
}
2. Largest of two numbers
public class Main {
    public static void main(String[] args) {
        int a=12,b=20;
        System.out.println(a>b?a:b);  // 20
    }
}
3. Largest of three numbers
public class Main {
    public static void main(String[] args) {
        int a=5,b=9,c=3;
        if(a>=b&&a>=c)System.out.println(a);
        else if(b>=c)System.out.println(b);
        else System.out.println(c);  // 9
    }
}
4. Positive, negative or zero
public class Main {
    public static void main(String[] args) {
        int n=-4;
        if(n>0)System.out.println("Positive");
        else if(n<0)System.out.println("Negative");
        else System.out.println("Zero");  // Negative
    }
}
5. Check pass or fail
public class Main {
    public static void main(String[] args) {
        int marks=45;
        if(marks>=33)System.out.println("Pass");
        else System.out.println("Fail");  // Pass
    }
}
6. Grade using if-else-if
public class Main {
    public static void main(String[] args) {
        int m=82;
        if(m>=90)System.out.println("A+");
        else if(m>=75)System.out.println("A");
        else if(m>=33)System.out.println("Pass");
        else System.out.println("Fail");  // A
    }
}
7. Check leap year
public class Main {
    public static void main(String[] args) {
        int y=2024;
        if((y%4==0&&y%100!=0)||y%400==0)System.out.println("Leap");
        else System.out.println("Not Leap");  // Leap
    }
}
8. Check vowel or consonant
public class Main {
    public static void main(String[] args) {
        char ch='e';
        if(ch=='a'||ch=='e'||ch=='i'||ch=='o'||ch=='u')System.out.println("Vowel");
        else System.out.println("Consonant");  // Vowel
    }
}
9. Divisible by 5 and 11
public class Main {
    public static void main(String[] args) {
        int n=55;
        if(n%5==0&&n%11==0)System.out.println("Yes");
        else System.out.println("No");  // Yes
    }
}
10. Largest using ternary
public class Main {
    public static void main(String[] args) {
        int a=7,b=4;
        System.out.println(a>b?a:b);  // 7
    }
}

Loop Programs (for/while)

1. Print 1 to 10
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=10;i++) System.out.print(i+" ");  // 1..10
    }
}
2. Sum of first N numbers
public class Main {
    public static void main(String[] args) {
        int n=5,sum=0;
        for(int i=1;i<=n;i++) sum+=i;
        System.out.println("Sum = "+sum);  // 15
    }
}
3. Factorial
public class Main {
    public static void main(String[] args) {
        int n=5,f=1;
        for(int i=1;i<=n;i++) f*=i;
        System.out.println("Factorial = "+f);  // 120
    }
}
4. Multiplication table
public class Main {
    public static void main(String[] args) {
        int n=5;
        for(int i=1;i<=10;i++) System.out.println(n+" x "+i+" = "+(n*i));
    }
}
5. Print even numbers 1-20
public class Main {
    public static void main(String[] args) {
        for(int i=2;i<=20;i+=2) System.out.print(i+" ");  // 2..20
    }
}
6. Reverse a number
public class Main {
    public static void main(String[] args) {
        int n=1234,rev=0;
        while(n>0){rev=rev*10+n%10;n/=10;}
        System.out.println(rev);  // 4321
    }
}
7. Sum of digits
public class Main {
    public static void main(String[] args) {
        int n=123,s=0;
        while(n>0){s+=n%10;n/=10;}
        System.out.println("Sum = "+s);  // 6
    }
}
8. Count digits
public class Main {
    public static void main(String[] args) {
        int n=98765,c=0;
        while(n>0){c++;n/=10;}
        System.out.println("Digits = "+c);  // 5
    }
}
9. Check prime
public class Main {
    public static void main(String[] args) {
        int n=13;boolean p=true;
        for(int i=2;i<n;i++) if(n%i==0) p=false;
        System.out.println(p?"Prime":"Not Prime");  // Prime
    }
}
10. Fibonacci series
public class Main {
    public static void main(String[] args) {
        int a=0,b=1,c;
        for(int i=0;i<7;i++){System.out.print(a+" ");c=a+b;a=b;b=c;}  // 0 1 1 2 3 5 8
    }
}

Pattern Programs (आकृति)

1. Square of stars
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=4;i++){for(int j=1;j<=4;j++)System.out.print("* ");System.out.println();}
    }
}
2. Right triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=5;i++){for(int j=1;j<=i;j++)System.out.print("* ");System.out.println();}
    }
}
3. Inverted triangle
public class Main {
    public static void main(String[] args) {
        for(int i=5;i>=1;i--){for(int j=1;j<=i;j++)System.out.print("* ");System.out.println();}
    }
}
4. Number triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=5;i++){for(int j=1;j<=i;j++)System.out.print(j+" ");System.out.println();}
    }
}
5. Repeated number triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=5;i++){for(int j=1;j<=i;j++)System.out.print(i+" ");System.out.println();}
    }
}
6. Right-aligned triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=4;i++){for(int j=i;j<4;j++)System.out.print("  ");for(int k=1;k<=i;k++)System.out.print("* ");System.out.println();}
    }
}
7. Pyramid of stars
public class Main {
    public static void main(String[] args) {
        int n=4;
        for(int i=1;i<=n;i++){for(int j=i;j<n;j++)System.out.print(" ");for(int k=1;k<=2*i-1;k++)System.out.print("*");System.out.println();}
    }
}
8. Alphabet triangle
public class Main {
    public static void main(String[] args) {
        for(int i=1;i<=5;i++){for(char c='A';c<'A'+i;c++)System.out.print(c+" ");System.out.println();}
    }
}
9. Diamond pattern
public class Main {
    public static void main(String[] args) {
        int n=3;
        for(int i=1;i<=n;i++){for(int j=i;j<n;j++)System.out.print(" ");for(int k=1;k<=2*i-1;k++)System.out.print("*");System.out.println();}
        for(int i=n-1;i>=1;i--){for(int j=n;j>i;j--)System.out.print(" ");for(int k=1;k<=2*i-1;k++)System.out.print("*");System.out.println();}
    }
}
10. Hollow square
public class Main {
    public static void main(String[] args) {
        int n=4;
        for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){if(i==1||i==n||j==1||j==n)System.out.print("* ");else System.out.print("  ");}System.out.println();}
    }
}

Array Programs (सरणी)

1. Sum of array
public class Main {
    public static void main(String[] args) {
        int[] a={10,20,30,40};int sum=0;
        for(int x:a) sum+=x;
        System.out.println("Sum = "+sum);  // 100
    }
}
2. Largest in array
public class Main {
    public static void main(String[] args) {
        int[] a={3,7,2,9,4};int mx=a[0];
        for(int x:a) if(x>mx) mx=x;
        System.out.println("Max = "+mx);  // 9
    }
}
3. Smallest in array
public class Main {
    public static void main(String[] args) {
        int[] a={3,7,2,9,4};int mn=a[0];
        for(int x:a) if(x<mn) mn=x;
        System.out.println("Min = "+mn);  // 2
    }
}
4. Average of array
public class Main {
    public static void main(String[] args) {
        int[] a={10,20,30};int s=0;
        for(int x:a) s+=x;
        System.out.println("Avg = "+(s/3.0));  // 20.0
    }
}
5. Reverse array
public class Main {
    public static void main(String[] args) {
        int[] a={1,2,3,4,5};
        for(int i=a.length-1;i>=0;i--) System.out.print(a[i]+" ");  // 5 4 3 2 1
    }
}
6. Count even numbers
public class Main {
    public static void main(String[] args) {
        int[] a={1,2,3,4,5,6};int c=0;
        for(int x:a) if(x%2==0) c++;
        System.out.println("Even = "+c);  // 3
    }
}
7. Linear search
public class Main {
    public static void main(String[] args) {
        int[] a={5,8,12,3};int key=12,pos=-1;
        for(int i=0;i<a.length;i++) if(a[i]==key) pos=i;
        System.out.println("Found at "+pos);  // 2
    }
}
8. Copy array
public class Main {
    public static void main(String[] args) {
        int[] a={1,2,3};int[] b=new int[3];
        for(int i=0;i<3;i++) b[i]=a[i];
        System.out.println(b[0]+""+b[1]+b[2]);  // 123
    }
}
9. Sort ascending
public class Main {
    public static void main(String[] args) {
        int[] a={5,2,8,1};int n=a.length;
        for(int i=0;i<n;i++)for(int j=0;j<n-i-1;j++)if(a[j]>a[j+1]){int t=a[j];a[j]=a[j+1];a[j+1]=t;}
        for(int x:a) System.out.print(x+" ");  // 1 2 5 8
    }
}
10. Count positive/negative
public class Main {
    public static void main(String[] args) {
        int[] a={-1,2,-3,4,5};int p=0,n=0;
        for(int x:a){if(x>=0)p++;else n++;}
        System.out.println("Pos="+p+" Neg="+n);  // Pos=3 Neg=2
    }
}
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