JVM方法分派

红太狼 2022-08-06 18:29 158阅读 0赞

方法静态分派演示

/**
     * 方法静态分派演示
     * Created by tiantao on 15-2-9.
     */
    public class StaticDispatch {
    
        static abstract class Human {
        }
    
        static class Man extends Human {
        }
    
        static class Woman extends Human {
        }
    
        public void sayHello(Human guy) {
            System.out.println("hello,guy!");
        }
    
        public void sayHello(Man guy) {
            System.out.println("hello,gentleman!");
        }
    
        public void sayHello(Woman guy) {
            System.out.println("hello,lady!");
        }
    
    
        public static void main(String[] args) {
            Human man = new Man();
            Human woman = new Woman();
            StaticDispatch testJVM = new StaticDispatch();
            testJVM.sayHello(man);
            testJVM.sayHello(woman);
    
        }
    }

执行输出：

hello,guy!  
hello,guy!

接下来是方法动态分派演示

/**
     * 方法动态分派演示
     * Created by tiantao on 15-2-9.
     */
    public class DynamicDispatch {
        static abstract class Human {
            protected abstract void sayHello();
        }
    
        static class Man extends Human {
    
            @Override
            protected void sayHello() {
                System.out.println("man say hello!");
            }
        }
    
        static class Woman extends Human {
    
            @Override
            protected void sayHello() {
                System.out.println("woman say hello!");
            }
        }
    
        public static void main(String[] args) {
            Human man = new Man();
            Human woman = new Woman();
            man.sayHello();
            woman.sayHello();
        }
    }

执行输出：

man say hello!  
woman say hello!

本来对方法重载和方法得重写概念挺清晰得，今天看了书里的这两个例子一下被带模糊了。

对第一个例子，静态分派的结果有点小意外。加强一下记忆。