Is Java really passing objects by value?

Possible Duplicate: Is Java pass by reference?

public class myClass{
    public static void main(String[] args){
        myObject obj = new myObject("myName");
        changeName(obj);
        System.out.print(obj.getName()); // This prints "anotherName"
    }
    public static void changeName(myObject obj){
        obj.setName("anotherName");
    }
}

I know that Java pass by value, but why does it pass obj by reference in previous example and change it?

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Java always passes arguments by value, NOT by reference. In your example, you are still passing obj by its value, not the reference itself. Inside your method changeName , you are assigning another (local) reference, obj , to the same object you passed it as an argument. Once you modify that reference, you are modifying the original reference, obj , which is passed as an argument.

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EDIT:

Let me explain this through an example:

public class Main
{
     public static void main(String[] args)
     {
          Foo f = new Foo("f");
          changeReference(f); // It won't change the reference!
          modifyReference(f); // It will change the object that the reference refers to!
     }
     public static void changeReference(Foo a)
     {
          Foo b = new Foo("b");
          a = b;
     }
     public static void modifyReference(Foo c)
     {
          c.setAttribute("c");
     }
}

I will explain this in steps:

1- Declaring a reference named f of type Foo and assign it to a new object of type Foo with an attribute "f" .

Foo f = new Foo("f");

2- From the method side, a reference of type Foo with a name a is declared and it's initially assigned to null .

public static void changeReference(Foo a)

3- As you call the method changeReference , the reference a will be assigned to the object which is passed as an argument.

changeReference(f);

4- Declaring a reference named b of type Foo and assign it to a new object of type Foo with an attribute "b" .

Foo b = new Foo("b");

5- a = b is re-assigning the reference a NOT f to the object whose its attribute is "b" .

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6- As you call modifyReference(Foo c) method, a reference c is created and assigned to the object with attribute "f" .

7- c.setAttribute("c"); will change the attribute of the object that reference c points to it, and it's same object that reference f points to it.

I hope you understand now how passing objects as arguments works in Java :)

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In Java, an object handle, or the identity of an object is considered a value. Passing by value means passing this handle, not a full copy of the object.

A "reference" in the term "pass by reference" also doesn't mean "reference to an object". It means "reference to a variable" – a named "bucket" in a function definition (or, rather, a call frame) that can store a value.

Passing by reference would mean the called method could change variable values in the calling method. (For example, in the C standard library, the function scanf works this way.) This isn't possible in Java. You can always change the properties of an object – they aren't considered a part of its "value". They're completely different independent objects.

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You're changing a property of obj , not changing obj (the parameter) itself.

The point is that if you pointed obj at something else in changeName that that change would not be reflected in main .

See this post for further clarification.

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