Java构造方法 代码块 static 执行顺序

class Demo {
    static Demo demo1 = new Demo();
    static Demo demo2 = new Demo();
    
    {
        System.out.println("构造代码块");   
    }
    
    static {
        System.out.println("静态代码块");  
    }
    
    public Demo() {
        System.out.println("构造方法");  
    }
    
    public static void main(String[] args) {
        Demo demo1 = new Demo();
    }
}
/*
问:
    代码执行流程!!!
*/

执行结果

构造代码块
构造方法
构造代码块
构造方法
静态代码块
构造代码块
构造方法


//静态属性之间按顺序执行
1.执行static Demo demo1 = new Demo();
2.构造代码块：初始化当前类所有的类对象，只要【使用new + 构造方法创建当前类对象】，就一定会执行构造代码块中的内容

 

---

 

class Demo {
    static int num1 = 10;
    static int num2 = 20;
    
    {
        System.out.println("构造代码块");
    }
    
    static {
        num1 = 20;
        num2 = 100;
    }
    
    public Demo() {
        System.out.println("构造方法");
    }
    
    public static void main(String[] args) {
        new Demo();
    }
}
/*
代码执行效果已经num1和num2的值是多少
*/

构造代码块
构造方法
20
100

 

---

 

// 每行代码后的“//1”为整个程序的调用流程
package randy2;
class Bowl {
    public Bowl(int marker) {//3//6//15//18//21//30//39
        System.out.println("Bowl(" + marker + ")");//4//7//16//19//22//31//40
    }

    public void f1(int marker) {
        System.out.println("f1(" + marker + ")");//11//26//35/44
    }
}

class Table {
    static Bowl bowl1 = new Bowl(1);//2

    public Table() {//8
        System.out.println("Table()");//9
        bowl2.f1(1);//10
    }

    public void f2(int marker) {
        System.out.println("f2(" + marker + ")");//46
    }

    static Bowl bowl2 = new Bowl(2);//5
}

class Cupboard {//13
    Bowl bowl3 = new Bowl(3);//20//29//38
    static Bowl bowl4 = new Bowl(4);//14

    public Cupboard() {//23//32//41
        System.out.println("Cupboard()");//24/33//42
        bowl4.f1(2);//25//34//43
    }

    public void f3(int marker) {
        System.out.println("f3(" + marker + ")");//48
    }

    static Bowl bowl5 = new Bowl(5);//17
}

public class StaticInit {
    public static void main(String[] args) {
        System.out.println("Creating new Cupboard() int main");//27
        new Cupboard();//28
        System.out.println("Creating new Cupboard() int main");//36
        new Cupboard();//37
        table.f2(1);//45
        cupboard.f3(1);//47
    }

    static Table table = new Table();//1
    static Cupboard cupboard = new Cupboard();//12
}

Bowl(1)
Bowl(2)
Table()
f1(1)
Bowl(4)
Bowl(5)
Bowl(3)
Cupboard()
f1(2)
Creating new Cupboard() int main
Bowl(3)
Cupboard()
f1(2)
Creating new Cupboard() int main
Bowl(3)
Cupboard()
f1(2)
f2(1)
f3(1)

 

父类静态代码块->子类静态代码块->父类非静态代码块->父类构造函数->子类非静态代码块->子类构造函数