Java類加載順序

package com.wang.thread;

import java.security.PublicKey;

/**
 * Created by wl893 on 2018/3/24.
 */
public class B {

    static int i = 0;
    static {
        System.out.println("ClassB --> static block B1 + " + i);
    }

    int j = 0;

    static {
        i++;
        System.out.println("ClassB -->static block2 +" + i);
}

    public B(){
        i++;
        j++;
        System.out.println("ClassB  contruct i:" + i + ";j:" + j);
    }

    {
        System.out.println("ClassB common block + " + i);
    }

    public void getValue() {
        i++;
        System.out.println("ClassB getvalueB:" + i);
    }

    public static void getValues() {
        i++;
        System.out.println("ClassB static getvaluesB:" + i);
    }

}






package com.wang.thread;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * Created by wl893 on 2018/3/24.
 */
public class A extends B {
    static int i = 0;
    static {
        System.out.println("ClassA --> static block B1 + " + i);
    }

    int j = 0;

    static {
        i++;
        System.out.println("ClassA -->static block2 +" + i);
    }

    public A(){
        i++;
        j++;
        System.out.println("ClassA  contruct i:" + i + ";j:" + j);
    }

    {
        System.out.println("ClassA common block + " + i);
    }

    public void getValue() {
        i++;
        System.out.println("ClassA getvalueA:" + i);
    }

    public static void getValues() {
        i++;
        System.out.println("ClassA static getvaluesA:" + i);
    }


//    public static int value1;
//    public static int value2 = 0;
//    private static A singleton2 = new A();
//
//
//    private A(){
//        value1++;
//        value2++;
//    }
//
//    public static A getInstance2(){
//        return singleton2;
//    }


    public static void main(String[] args) {
        A.getValues();
        A.i = 2;
        A a = new A();
        a.getValue();
//        A instance = A.getInstance2();
//        System.out.println("Instance 1 = " + instance.value1);
//        System.out.println("Instance 2 = " + instance.value2);

        ArrayList<String> arrayList = new ArrayList<>();

        System.out.println("ssss");
    }

}

輸出結果：

ClassB --> static block B1 + 0
ClassB -->static block2 +1
ClassA --> static block B1 + 0
ClassA -->static block2 +1
ClassA static getvaluesA:2
ClassB common block + 1
ClassB contruct i:2;j:1
ClassA common block + 2
ClassA contruct i:3;j:1
ClassA getvalueA:4
ssss

/**
 * 類加載順序：
 *  1.首先加載父類的靜態代碼塊
 *  2.在加載子類的靜態代碼塊
 *  3.加載父類的初始化代碼塊
 *  4.加載父類的構造方法
 *  5.加載子類的初始化代碼塊
 *  6.加載子類的構造方法
 *  7.調用子類的方法
 */