java构造方法里面super()的使用

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

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();
	}
}