Java Buzz Forum - Java Interview programs on Strings

1.Reverse a String Without using String API?

package com.instaceofjava;
public class ReverseString {
public static void main(String[] args) {
String str="Hello world";
String revstring="";
for(int i=str.length()-1;i>=0;--i){
revstring +=str.charAt(i);
}
System.out.println(revstring);
}
}

Program:

output: dlrow olleH.

2)Sorting the String without using String API?

package com.Instanceofjava;
public class SortString {
public static void main(String[] args) {
String original = "edcba";
int j=0;
char temp=0;
char[] chars = original.toCharArray();
for (int i = 0; i <chars.length; i++) {
for ( j = 0; j < chars.length; j++) {
if(chars[j]>chars[i]){
temp=chars[i];
chars[i]=chars[j];
chars[j]=temp;
}
}
}
for(int k=0;k<chars.length;k++){
System.out.println(chars[k]);
}
}
}

program:

output:abcde.

3.Sort the String with using String API?

program:

package com.instanceofjava;
public class SortString {
public static void main(String[] args) {
String original = "edcba";
char[] chars = original.toCharArray();
Arrays.sort(chars);
String sorted = new String(chars);
System.out.println(sorted);
}
}

OutPut:abcde

4.Check String is palindrome or not?

program:

Solution #1:

package com.instaceofjava;
public class PalindromeDemo{
public static void main(String[] args) {
String str="MADAM";
String revstring="";
for(int i=str.length()-1;i>=0;--i){
revstring +=str.charAt(i);
}
System.out.println(revstring);
if(revstring.equalsIgnoreCase(str)){
System.out.println("The string is Palindrome");
}
else{
System.out.println("Not Palindrome");
}
}
}

Output:

The string is Palindrome

Solution #2:

package com.instaceofjava;
import java.util.Scanner;
public class Palindrome {
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
System.out.println("Enter a string");
String str=in.nextLine();
StringBuffer strone=new StringBuffer(str);
StringBuffer strtwo=new StringBuffer(strone);
strone.reverse();
System.out.println("Orginal String ="+strtwo);
System.out.println("After Reverse ="+strone);
if(String.valueOf(strone).compareTo(String.valueOf(strtwo))==0)
System.out.println("Result:Palindrome");
else
System.out.println("Result:Not Palindrome");
}
}

Output:

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

Result:Palindrome

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

Program:

package com.instaceofjava;
import java.util.Scanner;
public class Palindrome {
public static void main(String[] args)
{
System.out.println("Please Enter a number : ");
int givennumber = new Scanner(System.in).nextInt();
int number=givennumber;
int reverse=0;
while (number != 0) {
int remainder = number % 10;
reverse = reverse * 10 + remainder;
number = number / 10;
}
if(givennumber == reverse)
System.out.println("Result:Palindrome");
else
System.out.println("Result:Not Palindrome");
}
}

Output:

Please Enter a number :
535
Result:Palindrome.

6.


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