决定调用父类的哪一个构造方法

1.Father.java

public class Father {	Father()	{		System.out.println("Father");	}		Father(int age)	{		System.out.println("Father is "+age);	}}

2.Son.java

public class Son extends Father{	Son()	{		super(20);  //不写默认调用父类无参数构造方法		System.out.println("son");	}		public static void main(String[] args) 	{		Son son = new Son();	}}