Java Interview programs on Strings

1.Reverse a String Without using String API?

1. package com.instaceofjava;
2.  
3. public class ReverseString {
4.  
5. public static void main(String[] args) {
6.  
7. String str="Hello world";
8. String revstring="";
9.  
10. for(int i=str.length()-1;i>=0;--i){
11. revstring +=str.charAt(i);
12. }
13.  
14. System.out.println(revstring);
15. }
16. }

Program:

output: dlrow olleH.

2)Sorting the String without using String API?

1. package com.Instanceofjava;
2.  
3. public class SortString {
4.  
5.  public static void main(String[] args) {
6.  
7.   String original = "edcba";
8.  int j=0;
9.    char temp=0;
10.  
11.      char[] chars = original.toCharArray();
12.      for (int i = 0; i <chars.length; i++) {
13.          for ( j = 0; j < chars.length; j++) {
14.          if(chars[j]>chars[i]){
15.              temp=chars[i];
16.              chars[i]=chars[j];
17.               chars[j]=temp;
18.           }
19.      }
20.   }
21.  
22.     for(int k=0;k<chars.length;k++){
23.     System.out.println(chars[k]);
24.    }
25.  
26.  }
27. }

program:

output:abcde.

3.Sort the String with using String API?

program:

1. package com.instanceofjava;
2.  
3.  public class SortString {
4.  
5.  public static void main(String[] args) {
6.    String original = "edcba";
7.  
8.    char[] chars = original.toCharArray();
9.    Arrays.sort(chars);
10.  
11.     String sorted = new String(chars);
12.      System.out.println(sorted);
13.  
14. }
15. }
    

OutPut:abcde

4.Check String is palindrome or not?

program:

Solution #1:

1. package com.instaceofjava; 
2.  
3. public class PalindromeDemo{ 
4.  
5. public static void main(String[] args) {
6.  
7. String str="MADAM";
8. String revstring="";
9.  
10. for(int i=str.length()-1;i>=0;--i){
11. revstring +=str.charAt(i);
12. }
13.  
14. System.out.println(revstring);
15.  
16. if(revstring.equalsIgnoreCase(str)){
17. System.out.println("The string is Palindrome");
18. }
19. else{
20. System.out.println("Not Palindrome");
21. }
22.  
23. }
24.  
25. }

  Output:

The string is Palindrome

Solution #2:

1. package com.instaceofjava;
2.  
3.   import java.util.Scanner;
4.  
5.  public class Palindrome {
6.  
7. public static void main(String[] args)
8. {
9.  
10. Scanner in = new Scanner(System.in);
11.  
12.  System.out.println("Enter a string");
13.  String str=in.nextLine();
14.  
15. StringBuffer strone=new StringBuffer(str);
16.  StringBuffer strtwo=new StringBuffer(strone);
17.  
18.   strone.reverse();
19.  
20. System.out.println("Orginal String ="+strtwo);
21. System.out.println("After Reverse ="+strone);
22.  
23. if(String.valueOf(strone).compareTo(String.valueOf(strtwo))==0)
24.    System.out.println("Result:Palindrome");
25.    else
26.     System.out.println("Result:Not Palindrome");
27.  
28.    }
29.  
30. }

 Output:

Enter a string
MOOM
Orginal String =MOOM
After Reverse =MOOM

Result:Palindrome

5.Program to Check given number is palindrome or not?

Program:

1.  package com.instaceofjava; 
2.  
3. import java.util.Scanner; 
4.  
5. public class Palindrome {
6.  
7. public static void main(String[] args)
8. {
9.  
10. System.out.println("Please Enter a number : ");
11.       int givennumber = new Scanner(System.in).nextInt();
12.       int number=givennumber;
13.        int reverse=0;
14.         while (number != 0) {
15.            int remainder = number % 10;
16.             reverse = reverse * 10 + remainder;
17.             number = number / 10;
18.         }           
19. if(givennumber == reverse)
20.    System.out.println("Result:Palindrome");
21.     else
22.     System.out.println("Result:Not Palindrome");
23.     }
24.  
25. }

 Output:

Please Enter a number :
535
Result:Palindrome.

 Also Read:

Java experience interview programming questions on Strings