Question

What is the difference between following code in Java? I couldn’t clearly catch out how objects are passed in Java. Can anyone explain the code below.

package cc;

public class C {

    public static class Value {
        private String value;

        public void setValue(String str) {
            value=str;
        }

        public String getValue() {
            return value;
        }
    }



    public static void test(Value str) {
        str.setValue("test");
    }

    public static void test2(Value str) {
        str=new Value();
        str.setValue("test2");
    }
    public static void main(String[] args) {
        String m="main";
        Value v=new Value();
        v.setValue(m);
        System.out.println(v.getValue()); // prints main fine
        test(v);
        System.out.println(v.getValue()); // prints 'test' fine
        test2(v);
        System.out.println(v.getValue()); // prints 'test' again after assigning to test2 in function why?
    }
}

Answer 1

In test2() a new instance is created and you are setting value in newer instance, and not in the Object whose reference is passed

public static void test2(Value str) {
        str=new Value();
        str.setValue("test2");
}

See Also

• Is Java "pass-by-reference" or "pass-by-value"?