一个奇怪的问题，……

Java code

public class TV extends Machine{    private String brand;    private int maxvolume;        public TV() {            }    public void work(){        System.out.println("Play audio and video meida");    }    public String toString(){        return "The power is "+getPower()+"\n"+"The voltage is "+getVoltage()+"\n"+"The current is "+getCurrent()+"\n"+"The type is "+getType()+"\n"+"The brand is "+brand+"\n"+"The maximum volume is "+maxvolume;    }    public static void main(String[] args) {        TV tv=new TV();        System.out.println(tv);            }}

System.out.println(tv);

为什么可以达到
System.out.println(tv.toString());
的效果？

父类Machine里面没有重写方法



[解决办法]
println（Object o)自动调用类的toString，没有重写的话就是 类名＠hashcode
[解决办法]
这个类中重写了toString方法，来判别对象是否相等。