JAVA构造方法，继承关系和SUPER关键字

class Test extends Object{
    public Test(){
        System.out.println("Test1 First thing");
    }
    public Test(String welcome){
        System.out.println("Test1 " + welcome);
    }
    protected void doSomething(){
        System.out.println("Test1 doSomething");
    }
    protected Test doit(){
        return new Test();
    }
}

class Test2 extends Test{
    public Test2(){
        super("welcome string");
        super.doSomething();
    }
    public Test2(String welcom){
        //super();
        super("welcome string");
        super.doSomething();
        System.out.println("Test2 " + welcom);
    }
    public void doSomethingnew(){
        System.out.println("Test2 doSomethingnew");
    }
    public void doSomething(){
        System.out.println("Test2 doSomething");
    }
    protected Test2 doit(){
        return new Test2();
    }
}
class HelloJava{
    public static void main(String[] args){
        Test test1 = new Test();
        Test2 test2 = new Test2("hello");
        test1.doSomething();
        test2.doSomething();
        test2.doSomethingnew();
        
    }
}