Java Programs


Set array elements to 1 if Prime

  • Program which will set the array element a[i] to 1 if i is prime, and to 0 if i is not prime.
Program

import java.util.Scanner;

public class PrimeArray {

            private static Scanner sc;
            public static void main(String[] args) {
                       
                        int limit,value;
                        PrimeArray ob=new PrimeArray();
                        sc=new Scanner(System.in);
                        int[] number=new int[1000];
                        System.out.println("Enter the number of elements in the array:");
                        limit=sc.nextInt();
                        System.out.println("Enter the elements of the array:");
                        for(int i=0;i<limit;i++) {
                                    number[i]=sc.nextInt();
                        }
                        for(int i=0;i<limit;i++) {
                                    value=ob.checkPrime(number[i]);
                                    number[i]=value;
                        }
                        System.out.println("Array after re-setting:");
                        for(int i=0;i<limit;i++) {
                                    System.out.println(number[i]);
                        }
                       
            }
           
            public int checkPrime(int num) {
                       
                        int flag=0;
                        for(int i=1;i<=num;i++) {
                                    if(num%i==0) {
                                                flag++;
                                    }
                        }
            if(flag==2) {
                        return 1;//is prime
            }
            else {
                        return 0;//is not prime
            }
                       
            }

}

Output

Enter the number of elements in the array:
5
Enter the elements of the array:
19
4
7
3
23
Array after re-setting:
1
0
1
1
1


Count vowels in a string

  • Program to count the number of vowels in a given string.
Program

import java.util.Scanner;

public class CountVowels {

            private static Scanner sc;
            public static void main(String[] args) {
                       
                        int flag=0,count=0;
                        sc=new Scanner(System.in);
                        System.out.println("Enter the String:");
                        String str=sc.nextLine();
                        for(int i=0;i<str.length();i++) {
                                    if((str.charAt(i)=='a')||(str.charAt(i)=='A')||(str.charAt(i)=='e')||(str.charAt(i)=='E')||
                                                            (str.charAt(i)=='i')||(str.charAt(i)=='I')||(str.charAt(i)=='o')||(str.charAt(i)=='O')||
                                    (str.charAt(i)=='u')||(str.charAt(i)=='U')) {
                                               
                                                count++;
                                                flag=1;
                                    }
                        }
                        if(flag==0) {
                                    System.out.println("There are no vowels in the string.");
                        }
                        else {
                                    System.out.println("The string contains "+count+" vowels.");
                        }
            }

}

Output

Enter the String:
Count the number of vowels.

The string contains 8 vowels.

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