swapping of objects in java [duplicate]

Answer 1

Java always passes the references by value. Read this answer for more details. However, you can swap two strings via arrays or wrapper classes.

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EDIT:

@dasblinkenlight shows how to use arrays to swap two strings, and here is an example of using wrapper class:

public class WrapperString
{
    public String text;

    public WrapperString(String text){this.text = text}

    @Override
    public String toString(){return text;}
}

public static void swap(WrapperString a, WrapperString b)
{
    String temp = a.text;
    a.text = b.text;
    b.text = temp;
}

public static void main(String[] args)
{
    WrapperString s1 = new WrapperString("Hello");
    WrapperString s2 = new WrapperString("World");

    swap(s1, s2);
    System.out.println(s1.text + s2.text);
    // or System.out.println(s1 + s2); since we've already overridden toString()
}

OUTPUT:

WorldHello