java - "if"语句中的局部变量错误 (Java)

Question

import java.util.Scanner;
import java.util.Random;
import static java.lang.System.out;

class TestingStuf {
    enum tooWhat {tooHigh, tooLow, justRight};

    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        Random myRandom = new Random();

        tooWhat guess;

        out.println("Pick a number between 1 and 10.");
        int userGuess = keyboard.nextInt(); 
        int randomNumber = myRandom.nextInt(10) + 1;

        if (userGuess < randomNumber) {
            guess = tooWhat.tooLow;
        }else if (userGuess > randomNumber) {
            guess = tooWhat.tooHigh;
        }else if (userGuess == randomNumber) {
            guess = tooWhat.justRight;
        }

        out.println("Your guess is:");

        if (guess == tooWhat.tooLow) {
            out.println("Too low.");

        }else if (guess == tooWhat.tooHigh) {
            out.println("Too high.");

        }else if (guess == tooWhat.justRight) {
            out.println("Correct!");

        }

            keyboard.close();
    }
}

在我的代码中，我在第二组“if”语句中出现错误，指出“局部变量猜测可能尚未初始化”，即使在前面的“if”语句中我给了“guess”变量一个值这取决于用户输入。我做错了什么？

Answer 1

如果你看一下你的代码，似乎有一条通过if...else if...else if的路径，其中猜测 从未被初始化。这就是编译器警告您的内容，因为随后的代码预计 guess 肯定会有一个值。

尽管我们作为人类知道这三个条件是互斥的，但编译器并不像我们那么聪明。只需将最后一个设置为 else 而不是 else if (...):

if (userGuess < randomNumber) {
    guess = tooWhat.tooLow;
}else if (userGuess > randomNumber) {
    guess = tooWhat.tooHigh;
}else { // *** No `if`
    guess = tooWhat.justRight;
}