先看一段Python代码
实现效果是子类和父类共用一个 sayHello() 方法，通过覆写属性name 输出不同的属性
class Parent(): name = "parent" def getName(self): return self.name def sayHello(self): print(self.name, "-", self.getName()) class Child(Parent): name = "child" if __name__ == "__main__": parent = Parent() print(parent.getName()) parent.sayHello() child = Child() print(child.getName()) child.sayHello()
输出效果满足预期要求
parent
parent - parentchild
child - child
再来看Java代码
class Parent {
private String name = "parent";
public String getName() {
return name;
}
public void sayHello() {
System.out.println(name + " - " + getName());
}
}
class Child extends Parent {
private String name = "child";
}
public class Demo {
public static void main(String[] args) {
Parent parent = new Parent();
System.out.println(parent.getName());
parent.sayHello();
Child child = new Child();
System.out.println(child.getName());
child.sayHello();
}
}
输出结果和预期不一样
parent
parent - parent
parent
parent - parent
修改一下子类，覆写父类的getName()方法
class Parent {
private String name = "parent";
public String getName() {
return name;
}
public void sayHello() {
System.out.println(name + " - " + getName());
}
}
class Child extends Parent {
private String name = "child";
// 增加方法覆写
@Override
public String getName() {
return name;
}
}
public class Demo {
public static void main(String[] args) {
Parent parent = new Parent();
System.out.println(parent.getName());
parent.sayHello();
Child child = new Child();
System.out.println(child.getName());
child.sayHello();
}
}
输出结果看到，通过覆写方法获取属性的方式可以获取子类属性，直接获取的属性还是父类中的属性
parent
parent - parent
child
parent - child
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