Java 构造函数及类成员变量初始化顺序

父类静态成员变量  -> 本类静态变量 -> 父类非静态变量 -> 父类构造函数 -> 本类非静态变量 -> 本类构造函数

Demo:

public class Main {

    public static void main(String[] args) {
        TestClass tc = new TestClass();
    }

    private static class base {
        public base(String id) {
            System.out.println("base initialized :"+id);
        }
    }
    private static class Parent {
        base b2 = new base("b2");
        static base b4 = new base("b4");
        public Parent() {
            System.out.println("Parent initialized.");
            testSync();
        }
        public void testSync() {
            System.out.println("Parent testSync.");
        }
    }

    private static class TestClass extends Parent{
        private final static base b = new base("b1");
        private final base b3 = new base("b3");
        public TestClass() {
            //super();
            synchronized(b3) {
                System.out.println("TestClass initialized.");
            }
        }
        @Override
        public void testSync() {
            synchronized(b) { //crash on synchronized(b3)
                System.out.println("TestClass testSync.");
            }
        }
    }
}

输出：

base initialized :b4
base initialized :b1
base initialized :b2
Parent initialized.
TestClass testSync.
base initialized :b3
TestClass initialized.