Java Program to Swap Two Strings

In this post, we will write a simple Java Program to swap two strings without using a third String variable.

The login is very simple, first add two string then use substring method to get sub-string from s1 and s2.

s1 = s1 + s2;
s2 = s1.substring(0, s1.length() - s2.length());
s1 = s1.substring(s2.length());

Java Program to Swap Two Strings without Third String Variable

/**
 * Java Program to Swap Two Strings without Third String Variable
 * @author javaguides.net
 *
 */
public class SwapTwoStrings {
    public static void main(String[] args) {
        String s1 = "javaguides";

        String s2 = "javadesignpatterns";

        display("Before Swapping :", s1, s2);

        // Swapping starts

        s1 = s1 + s2;

        s2 = s1.substring(0, s1.length() - s2.length());

        s1 = s1.substring(s2.length());

        // Swapping ends

        System.out.println("After Swapping :");
        display("After Swapping :", s1, s2);
    }

    private static final void display(String str, String s1, String s2) {
        System.out.println(str);
        System.out.println("s1 : " + s1);
        System.out.println("s2 : " + s2);
    }
}

Output:

Before Swapping :
s1 : javaguides
s2 : javadesignpatterns
--------------------------
After Swapping :
s1 : javadesignpatterns
s2 : javaguides
--------------------------

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

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