Swapping two Strings without using third variable

import java.io.*;
class Swap_Strings
    public static void main(String args[])throws IOException
        BufferedReader br=new BufferedReader (new InputStreamReader (System.in));
        System.out.print("Enter the 1st String : ");
        String s1=br.readLine();
        int len1=s1.length();
        System.out.print("Enter the 2nd String : ");
        String s2=br.readLine();
        System.out.println("Strings Before Swapping : ");
        System.out.println("1st String = "+s1);
        System.out.println("2nd String = "+s2);
        /*Swapping Process Begins*/
        /*Swapping Process Ends*/
        System.out.println("Strings After Swapping : ");
        System.out.println("1st String = "+s1);
        System.out.println("2nd String = "+s2);


Enter the 1st String : Java For
Enter the 2nd String : School is Fun
Strings Before Swapping :
1st String = Java For
2nd String = School is Fun
Strings After Swapping :
1st String = School is Fun
2nd String = Java For


Initially s1 = “Java For” and s2 = “School is Fun”,
Now, the variable, ‘len1’ stores the length of the 1st String. Hence, in this case, ‘len1’ = 8
Step 1: s1 = s1+s2; gives s1 = “Java For”+”School is Fun”;
i.e. s1 = “Java ForSchool is Fun” [Note: There will be no space when we join the 1st and the 2nd String]
Step 2: s2=s1.substring(0,len1); gives, s2=”Java ForSchool is Fun”.substring(0,8);
i.e. s2 = “Java For”
Step 3: s1 = s1.substring(len1); gives, s1 = “Java ForSchool is Fun.substring(8);
i.e. s1 = “School is Fun”
Hence, finally we have s1 = “School is Fun” and s2 = “Java For”. [Swapping Done]

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