多态
public class Uncle {
private String name;
private int age;
public void fahongbao(){
System.out.println("舅舅发红包");
}
子类一:
public class UncleOne extends Uncle{
public void fahongbao(){
System.out.println("大舅发红包");
}
public void songyan(){
System.out.println("大舅喜欢送烟");
}
}
子类二：
public class UncleTwo extends Uncle{
public void fahongbao(){
System.out.println("二舅发红包");
}
}
多态
UncleOne dajiu=new UncleOne();
dajiu.fahongbao();//大舅发红包
Uncle uncleTwo=new UncleTwo();
uncleTwo.fahongbao();//二舅发红包
向上转型
Uncle dajiu1=new UncleOne();
dajiu1.fahongbao();//大舅发红包
向下转型
Uncle dajiu1=new UncleOne();
dajiu1.fahongbao();
//dajiu1.songyan(); //会报错 子类独有的方在发生向上转型的时候无法在父类中使用
UncleOne temp=(UncleOne)dajiu1;//向下转型
temp.songyan();//可以调用子类独有的方法
instancesof
判断对象是否是指定的类型的实例
避免发生错误的类型转换
public class Demo01 {
public static void main(String[] args) {
Uncle uncle1=new UncleOne();
Uncle uncle2=new UncleTwo();
if(uncle1 instanceof UncleOne){
UncleOne u1=(UncleOne) uncle1;
u1.fahongbao();
}
if (uncle2 instanceof UncleTwo){
UncleTwo u2=(UncleTwo) uncle2;
u2.fahongbao();
}
}
