方法调用面试题

问题一：下面代码输出的结果

详细解析可见 方法调用

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 sr = new StaticDispatch();
        sr.sayHello(man);
        sr.sayHello(woman);
    }
}

问题二：下面代码依次输出的结果

详细解析可见 方法调用

public class Overload {
    public static void sayHello(Object arg) {
        System.out.println("hello Object");
    }
    public static void sayHello(int arg) {
        System.out.println("hello int");
    }
    public static void sayHello(long arg) {
        System.out.println("hello long");
    }
    public static void sayHello(Character arg) {
        System.out.println("hello Character");
    }
    public static void sayHello(char arg) {
        System.out.println("hello char");
    }
    public static void sayHello(char... arg) {
        System.out.println("hello char...");
    }
    public static void sayHello(Serializable arg) {
        System.out.println("hello Serializable");
    }
    public static void main(String[] args) {
        sayHello('a');
    }
}

依次注释掉方法

• sayHello(char arg)
• sayHello(int arg)
• sayHello(long arg)
• sayHello(Character arg)
• sayHello(Serializable arg)
• sayHello(Object arg)

它会输出什么？！

问题三：下面代码输出的结果

详细解析可见 方法调用

public class FieldHasNoPolymorphic {
    static class Father {
        public int money = 1;
        public Father() {
            money = 2;
            showMeTheMoney();
        }
        public void showMeTheMoney() {
            System.out.println("I am Father, i have $" + money);
        }
    }
    static class Son extends Father {
        public int money = 3;
        public Son() {
            money = 4;
            showMeTheMoney();
        }
        public void showMeTheMoney() {
            System.out.println("I am Son, i have $" + money);
        }
    }
    public static void main(String[] args) {
        Father guy = new Son();
        System.out.println("This guy has $" + guy.money);
    }
}