Java sharing same values in a class

问题

I have a class called Hand and another class to test it. Hand uses global variables and change their values with some methods if in class test I create two variables of the Hand class changes in one of the variables will affect the other. How can I make them separate ?

Class Hand:

private static List<Card> hand = new ArrayList<Card>();

Class Test:

        Hand hand1 = new Hand();
        Hand hand2 = new Hand();

If I add values to hand1 arraylist it changes also the values of hand2 arraylist. Can I separate them?

回答1:

Turn the private static List<Card> into a private List<Card>.

回答2:

Make private List<Card> hand = new ArrayList<Card>(); as instance variable rather then make it static..
Coz static is property of class and instance variables are property of Object... which is different for different Object ..but in case of static they are same for all objects..

回答3:

Remove the static modifier which is common for all instance of the class loaded in a particular class loader.

回答4:

The static keyword makes the variable class-scoped, not instance-scoped. That means the same value is common for all instances of the class. A non-static member is particular to every instance of the class. Remove the static keyword and you will get the desired behavior.

来源：https://stackoverflow.com/questions/7925447/java-sharing-same-values-in-a-class