java - 如何将枚举与 switch 语句一起使用？

Question

所以我查看了网站上的一些示例，但没有找到任何需要的东西。我想做的练习是将枚举类链接到页面底部的 switch 语句。

这个小部分的练习题是:“talk 方法应该要求用户输入一个短语，该短语应该打印在控制台上。娱乐机器人可以在四个方向(向前、向后、向左、向右)之一行走任意步数。因此，步行方法应该询问用户他们希望机器人走多少步以及朝哪个方向走。请注意，您必须验证用户的输入。说明必须存储为枚举并适当访问。”

枚举类:

package robot;

public enum Directions {
    FORWARD, BACKWARD, LEFT, RIGHT;
}

主类:

package robot;

import java.util.Scanner;

public class EntertainmentRobot extends Robot implements Walk, Talkable {

    private Directions direction;

    public EntertainmentRobot(double height, double weight, String manufacturer, String name) {
        super(height, weight, manufacturer, name);
        setEnergy(10);
        setEnergyUnitsRequired(0.75);
    }

    // ACCESSOR METHOD
    public Directions getDirection() {
        return direction;
    }

    // MUTATOR METHOD
    public void setDirection(Directions direction) {
        this.direction = direction;
    }

    @Override
    public void start() {
        System.out.println("-----I AM THE ENTERAINIMENT ROBOT-----");
    }

    @Override
    public void stop() {
        System.out.println("I have stopped entertaining people.");
    }

    @Override
    public void doTask() {
        // TODO Auto-generated method stub
    }

    @Override
    public void doTask(Scanner in) {
        System.out.println("I am entertaining people.");
        System.out.println("How many people would you like to play with me?");
        int times = in.nextInt();
        for (int i = 0; i < times; i++) {
            play();
        }
        System.out.println(" ");
    }

    public String toString() {
        return "[Name= " + getName() + "\nWeight= " + getWeight() + "\nHeight:" + getHeight() + "\nManufacturer: "
            + getManufacturer() + "\nPurpose: " + getPurpose() + "]";
    }

    public void play() {
        if (getEnergy() >= energyRequired()) {
            energyComsumption();
        } else {
            System.out.println("\n-----WHOOPS-----");
            System.out.println("I do not have enough energy to study");
            regenerate();
            System.out.println("I must get more energy");
            System.out.println("I have regenerated my energy");
        }
    }

    @Override
    public void talk(Scanner in) {
        System.out.println("Please enter a phrase for me to speak: ");
        String talk = in.nextLine();
        System.out.println("You asked me to say the following phrase: " + talk);
    }

    @Override
    public void walk(Scanner in) {
        System.out.println("Would you like me to walk? [YES/NO]");
        String walk = in.nextLine();
        if (walk.equalsIgnoreCase("Yes")) {
        }
    }

    public void directionChoice(Scanner in) {
        System.out.println("For how many paces?");
        int paces = in.nextInt();
        System.out.println("1 - FORWARD" + "2 - BACKWARD" + "3 - LEFT" + "4 - RIGHT");
        switch (paces) {
        case 1: 
            break;
        case 2:
        }
    }
}

Answer 1

下面是如何在 switch 情况下使用 Direction 枚举的示例:

Direction direction = //get direction input
switch(direction){
case BACKWARD:
    //do something
    break;

case FORWARD:
    //do something
    break;

case LEFT:
    //do something
    break;

case RIGHT:
    //do something
    break;
}

但是，在执行这个开关之前，我们需要获取这个枚举的值，我猜它是用户输入(字符串)。我们可以使用枚举的valueOf()方法来获取实际值。请注意，如果输入不是值之一，valueOf() 会抛出 IllegalArgumentException，因此我们可以执行以下操作来验证用户输入:

String input = //get user's input
Direction direction;
try{
    direction = Direction.valueOf(input);
}catch(IllegalArgumentException iae){
    //Invalid input
}