问答程序问题

Question

我对Java相当陌生，我有一项任务，我必须创建5个问题和答案，并让用户回答它们。然后，程序应该输出五个中的正确结果，以及百分比和反馈信息。我的代码如下。

package quiz;
import javax.swing.*;

public class Quiz {

    public static void main(String[] args) {

        int count = 0;
        final int totalQuestions = 5;

        JOptionPane.showMessageDialog(null, "Welcome to the Trivia Program!");
        JOptionPane.showMessageDialog(null, "A series of questions will be asked."
                + "\nPlease enter the letter of the answer"
                + "\nyou think is the correct choice.");

        String[][] question = {
            {"What letter is used to represent the number 100 in Roman Numerals?"
                + "\nA. M"
                + "\nB. D"
                + "\nC. C"
                + "\nD. X", "c"
            },
            {"Triton is the moon to which planet?"
                + "\nA. Jupiter"
                + "\nB. Neptune"
                + "\nC. Saturn"
                + "\nD. Uranus", "b"
            },
            {"What are Lanthanides?"
                + "\nA. Elements of the periodic table"
                + "\nB. Mountains on Earth"
                + "\nC. Mountains on the moon"
                + "\nD. Bacterium", "a"
            },
            {"What does a nidoligist study?"
                + "\nA. waves"
                + "\nB. clouds"
                + "\nC. bird nests"
                + "\nD. caves", "c"
            },
            {"Hypermetropic people are what?"
                + "\nA. obese"
                + "\nB. underfed"
                + "\nC. moody"
                + "\nD. far sighted", "d"
            }
        };

        String[] answers = new String[totalQuestions];

        for (int x = 0; x < totalQuestions; x++) {

            answers[x] = JOptionPane.showInputDialog("\t\t" + (x + 1) + ". " + question[x][0] + "   ");
            answers[x] = answers[x].toLowerCase();

            if (question[x][1].equals(answers[x])) {
                JOptionPane.showMessageDialog(null, "Correct!");
                count++;
            } else {
                JOptionPane.showMessageDialog(null, "Incorrect");
            }
        }

        int avg = (count / totalQuestions) * 100;

        switch (count) {
            case 3:
                JOptionPane.showMessageDialog(null, "You got " + count + "/" + totalQuestions + " correct"
                        + "(" + avg + "%)"
                        + "\nAverage");
                break;
            case 4:
                JOptionPane.showMessageDialog(null, "You got " + count + "/" + totalQuestions + " correct"
                        + "(" + avg + "%)"
                        + "\nVery Good");
                break;

            case 5:
                JOptionPane.showMessageDialog(null, "You got " + count + "/" + totalQuestions + " correct"
                        + "(" + avg + "%)"
                        + "\nExcellent!");
                break;

            default:
                JOptionPane.showMessageDialog(null, "You got " + count + "/" + totalQuestions + " correct "
                        + "(" + avg + "%)"
                        + "\nPoor");
                break;
        }
    }
}

我的问题是，只有当所有答案都正确时(5/5)，它才能输出正确的平均%。任何其他的，百分比是0。有人能帮我解释一下吗？

Answer 1

您需要从以下代码中更改这一行代码：

int avg = (count / totalQuestions) * 100;

至

float avg= ((float)count/(float)totalQuestions) * 100;

编辑：

To get the format like XX.XX%, you need to use string formatter:

String.format("%,.2f", avg);

Answer 2

在Java中除以两个整数时，结果是一个整数。为了得到一个百分比，你可以像这样把整数转换成浮点数/双数。

int avg = (int)((((double)count) / ((double)totalQuestions)) * 100.0)