Java中多态的示例 [英] example of polymorphism in java

问题描述

我是Java的初学者，所以对不起，这个问题对您来说太简单了.

I'm beginner in Java, so, i'm sorry if the question will be too simple for you.

有人可以解释一下Java中的多态性吗? 我只需要简单描述它的一段代码.

Could somebody explain me what the polymorphism is in Java? I need just piece of code that describes it simply.

谢谢.

推荐答案

我喜欢做家庭作业，但是我很无聊，Java使我怀旧.

Looks like homework to me, but I'm bored and Java makes me nostalgic.

List<A> list = new ArrayList<A>();
list.add(new A());
list.add(new A());
list.add(new B());

public void printAll() {
    for(A i : list) {
        System.out.println(i.print());
    }
}

class A {
    public String print() {
        return "A";
    }
}

class B extends A {
    @Override
    public String print() {
        return"B";
    }
}

输出如下:

    A
    A
    B

多态部分是针对同一方法调用执行不同的代码时.循环每次都执行相同的操作，但是实际上可能会调用不同的实例方法.

The polymorphic part is when different code is executed for the same method call. The loop does the same thing everytime, but different instance methods may actually be getting called.

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