java - 私有(private)静态字段不是最终的？

Question

有人能给我举个例子，说明何时在 private static final 字段上使用 private static 字段吗？我很难想出一个示例，说明您何时想要声明一个 private 类变量，该变量可能会发生变化。

Answer 1

输入单例模式:

public class Clazz {

    public static void main(String[] args) {
        MyObject myObject = MyObject.getInstance();
    }
}

class MyObject {
    private static MyObject instance; 
    //I belong to the class, but I need not be created before somebody wants me.

    private MyObject() {
    }

    public static MyObject getInstance() {
        if (instance == null) {
            instance = new MyObject();
        }
        return instance;
    }
}