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Thread: Passing reference to multiple classes in java

  1. #1
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    Default Passing reference to multiple classes in java


    I am a beginner in java programming basically, I am trying to make my code object-oriented. I have a set of 3 games in which all of them have players, frame, board, buttons etc. what I want is instead of declaring in every game the buttons and the board or the player, etc, again and again, I want to reference the class with the players or the board, etc. how am i supposed to do that?

  2. #2
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    Default Re: Passing reference to multiple classes in java

    I'm not certain I fully understand the overall design. However, classes may be shared between projects and you may also pass instances of a class to other classes via methods. One example might be a checkers and a chess game. There is no need to have two board classes since they are both the same.
    In both chess and checkers you could say

    Board board = new Board();

    and use that board instance for the game.


  3. #3
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    Sep 2018
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    Default Re: Passing reference to multiple classes in java

    Java is strictly pass-by-value, it's just that the values are often references.) When you change the value within that object using theBar.foo.a , then looking at the value of a again using theFoo.a will see the updated value. Basically, Java doesn't copy objects unless you really ask it to.
    public class FooClass {
    BarClass bar = null;
    int a = 0;
    int b = 1;
    int c = 2;

    public FooClass(BarClass bar) {
    this.bar = bar;

    public class BarClass {
    FooClass foo = null;

    public BarClass(){}

    public void setFoo(FooClass foo) {
    this.foo = foo;

    BarClass theBar = new BarClass();
    FooClass theFoo = new FooClass(theBar);
    theFoo.a //should be 0
    theBar.foo.a = 234; //I change the variable through theBar. Imagine all the variables are private and there are getters/setters.

    theFoo.a //should be 234 <-----
    How can I pass an object to another class, make a change, and have that change appear in the original instance of the first object?

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