线程“main”中的异常 java.lang.AssertionError。 我该怎么办？

Question

I am trying to make a program which will take a random guess from a range of numbers and checks whether it matches with the given number.

It will run 10times, it the program guesses the correct answer then it will terminate but if not then it will terminate with rejection.

at GuessingTest.main(GuessingTest.java:33)
**current directly** ; /usr/bin/env /Li
brary/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home/bin/java @/var/folders/zl/r96mn6p116125gw39hst2gp40000gn/T/cp_2tq0yp3psptn6qjx3o6su
w328.argfile GuessingTest 
Exception in thread "main" java.lang.AssertionError
        at org.junit.Assert.fail(Assert.java:87)
        at org.junit.Assert.assertTrue(Assert.java:42)
        at org.junit.Assert.assertTrue(Assert.java:53)
        at GuessingTest.guess(GuessingTest.java:30)
        at GuessingTest.main(GuessingTest.java:35)

Below is my code Guessing.java

public class Guessing {

    // Your local variables here
    private int low = 0;
    private int high = 1000;
    int randomNum;

    /**
     * Implement how your algorithm should make a guess here
     */
    public int guess() {
        randomNum = (int) ((Math.random() * (low - high)) + low);
        return randomNum;
    }

    /**
     * Implement how your algorithm should update its guess here
     */
    public void update(int answer) {
        if (answer == 1) {
            low = randomNum;
        } else if (answer == -1) {
            high = randomNum;
        }
    }
}

GuessingTest.java

import org.junit.Test;

import java.util.Random;

import static org.junit.Assert.*;

public class GuessingTest {


    @Test
    public void guess() {
        Random r = new Random();
        int hiddenNumber = r.nextInt(1001);

        Guessing g = new Guessing();

        int remainingGuesses = 10;
        while (remainingGuesses >= 0) {
            int guess = g.guess();
            if (guess == hiddenNumber) {
                break;
            } else if(guess > hiddenNumber) {
                g.update(1);
                remainingGuesses--;
            } else {
                g.update(-1);
                remainingGuesses--;
            }
        }
        assertTrue(remainingGuesses >= 0);
    }

    public static void main(String[] args) {
        GuessingTest test = new GuessingTest();
        test.guess();
    }
}

Answer 1

The exception you're getting is a result of failing the guess() test.

assertTrue(remainingGuesses >= 0);

In other words, you're expecting the hiddenNumber to be found within 11 steps (0..10), but it's not. And there's no reason for it to be. Your code returns negative numbers.

Also it wouldn't work even if it was returning positive numbers, since you could easily guess 0, 1, 2... up to 10, ending with 10 as low and 1000 as high .

Also -- how to get random numbers within a specific range: https://stackoverflow.com/a/5887745/684296