Think in Java Class Loading

Java类加载问题思考

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public abstract class C {
    static boolean flag = false;
}
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public class A extends C {

    static {
        System.out.println("static A");
        if (!flag) {
            System.out.print("load from A");
            D.load();
            flag = true;
        }
    }


    public A() {
        System.out.println("constructor A");

    }

    @Override
    public String toString() {
        return "A{" + flag + "}";
    }
}
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public class B extends C {

    static {
        System.out.println("static B");
        if (!flag){
            System.out.print("load from B");
            D.load();
            flag = true;
        }
    }

    public B(){
        System.out.println("constructor B");
    }

    @Override
    public String toString() {
        return "B{" + flag + "}";
    }
}
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public class D {
    static List<C> list = Lists.newArrayList();

    static {
        System.out.println("D 1 size=" + list.size() + ", " + list);
        list.add(new A());
        System.out.println("D 2 size=" + list.size() + ", " + list);
        list.add(new B());
        System.out.println("D 3 size=" + list.size() + ", " + list);

    }


    public static void load() {
        System.out.println("loading>>>>>>>>>>" + " list=" + Arrays.deepToString(list.toArray()));

        if (!C.flag) {
            for (C s : list) {
                System.out.println("loading.............." + s.getClass().getSimpleName() + " list=" + Arrays.deepToString(list.toArray()));
            }
        }
    }

}
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public class Test {

    public static void main(String []ar){
        A a = new A();
//        B a = new B();

    }
}