✅ Practice + Quiz · Lesson 26

50 Java Practice Programs

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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
    }
}

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)