General Java Programs

Common exam-style Java programs built on top of Chapter 01 concepts.

Program 1: Sum and Average of an Integer Array

The following program stores a fixed list of integers in an array, uses an enhanced for -loop to compute the sum, and then divides by the length of the array to find the average.

SumAvgOfArray.java

// WAP to calculate total/sum and average of integer array

public class SumAvgOfArray {
  
		public static void main(String arr[]) {
				int sum = 0, avg;
				int array[] = {10, 20, 30, 40, 50};
        
				for (int num : array) {
						sum = sum + num;
				}

				int n = array.length;
				avg = sum / n;
        
				System.out.println("Total: " + sum);
				System.out.println("Average: " + avg);
		}
}

Reference & full codeView on GitHub

Output:

Total: 150
Average: 30

Program 2: Check Number is Prime or Not

This program reads an integer from the user and checks whether it is a prime number by testing divisibility from 2 up to num - 1 . If no divisor is found, the number is prime.

PrimeOrNot.java

// WAP to check whether a number is prime or not

import java.util.Scanner;

public class PrimeOrNot {
		public static void main(String[] args) {
				Scanner sc = new Scanner(System.in);
				System.out.print("Enter Number:");
				int num = sc.nextInt();

				int temp = num;
				int i;
				for (i = 2; i < num; i++) {
						if (num % i == 0) {
								break;
						}
				}

				if (temp == i) {
						System.out.println("The Number " + temp + " is Prime.");
				} else {
						System.out.println("The Number " + temp + " is Not a Prime");
				}
				sc.close();
		}
}

Reference & full codeView on GitHub

Output:

Enter Number:5
The Number 5 is Prime.

Program 3: Pattern Printing - Right Angled Triangle

The following program uses nested for-loops to print a right-angled triangle pattern of asterisks. The outer loop controls the number of rows, while the inner loop prints the asterisks in each row.

BasicPattern01.java

public class BasicPattern01 {
     public static void main(String arr[]) {
        for(int i=0;i<10;i++) {
            for(int k=0;k<i;k++){
                System.out.print("* ");
            }
            System.out.println(" ");
        }
    }
}

Reference & full codeView on GitHub

Output:

* 
* * 
* * * 
* * * * 
* * * * * 
* * * * * * 
* * * * * * * 
* * * * * * * * 
* * * * * * * * *

Program 4: Pattern Printing - Right Angled Triangle (Inverted)

This program prints an inverted right-angled triangle pattern of asterisks using nestedfor-loops. The outer loop controls the number of rows, while the inner loops handle the spaces and asterisks in each row to create the inverted effect.

BasicPattern02.java

public class BasicPattern02 {
    public static void main(String arr[]) {
         for(int i=0;i<10;i++) {
            for(int k=0; k<i; k++){
                System.out.print("  ");
            }
            for(int j=10;j>i;j--) {
                System.out.print("* ");
            }
            System.out.println(" ");
        }
    }
}

Reference & full codeView on GitHub

Output:

* * * * * * * * * *  
  * * * * * * * * *  
    * * * * * * * *  
      * * * * * * *  
        * * * * * *  
          * * * * *  
            * * * *  
              * * *  
                * *  
                  *

Program 5: A Simple Vowel Checker

This program prompts the user to enter an alphabet character and uses a switch-case statement to check if the entered character is a vowel (a, e, i, o, u). If it matches any of the vowel cases, it confirms that the character is a vowel; otherwise, it states that the character is a consonant.

VowelChecker.java

// Simple Vowel Checker Program in Java

import java.util.Scanner;

public class VowelChecker {
    
    public static void main(String arr[]) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter Alphabet: ");
        String alphabet = sc.next();
        
        switch(alphabet) {
            case "a": 
                System.out.println("Yes the alphabet is Vowel");
                break;
                
            case "e": 
                System.out.println("Yes the alphabet is Vowel");
                break;
                
            case "i": 
                System.out.println("Yes the alphabet is Vowel");
                break;
                
            case "u": 
                System.out.println("Yes the alphabet is Vowel");
                break;
                    
            default : 
                System.out.println("The Alphabet is Consonant");
               }
        sc.close();
        
        
    }
    
}

Reference & full codeView on GitHub

Output:

Enter Alphabet: u
Yes the alphabet is Vowel

Program 6: Fibonacci Series

This program generates and prints the Fibonacci series up to a specified number of terms (10 in this case). It initializes the first two terms and iteratively calculates the next terms by summing the previous two, printing each term in the series.

Fibonacci.java


public class Fibonacci {
    public static void main(String[] args) {
        int n = 10; 
        int firstTerm = 0, secondTerm = 1;

        System.out.println("Fibonacci Series up to " + n + " terms:");

        for (int i = 1; i <= n; ++i) {
            System.out.print(firstTerm + ", ");

            int nextTerm = firstTerm + secondTerm;
            firstTerm = secondTerm;
            secondTerm = nextTerm;
        }
    }
}

Reference & full codeView on GitHub

Output:

Fibonacci Series up to 10 terms:
0, 1, 1, 2, 3, 5, 8, 13, 21, 34,

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