Question

此程序的目的是让用户尝试猜测计算机随机选择的最多20个数字。用户输入他们的猜测。然后计算机告诉用户他们的猜测是太高还是太低。用户不断输入他们的猜测直到猜测正确。然后他们被告知他们花了多少猜测。问题是我不明白程序中的算术表达式是否生成从1到20的随机数，因为当我输入1到20之间的数字时，弹出窗口显示“数字太大”＃39;

package pkTopic6Exercise13;
import javax.swing.*;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.Font;
public class Topic6Exercise13 
{
private GuessingGame MyGuessingGame = new GuessingGame();
private Topic6Exercise13()
{//constructor      
}
public static void main(String[] args) 
{
    Topic6Exercise13 myTopic6Exercise13 = new Topic6Exercise13();
    myTopic6Exercise13.go();
}
private void go()
{
    T6Ex13GUIin myT6Ex13GUIin = new T6Ex13GUIin();
}
private class GuessingGame
{
    private int NumToGuess=0;
    private int Guess=0;
    private int NumGuesses=0;
    private GuessingGame()
    {//constructor          
    }
    private void GenerateNum()
    {
        NumToGuess = 1+(int)(20*Math.random());
    }
    private String CheckNum()
    {
        NumGuesses = NumGuesses + 1;
        if (Guess > NumToGuess)
        {
            JOptionPane.showMessageDialog(null, Guess + " is too BIG!");
            return "NotGuessed";
        }
        else if (Guess < NumToGuess)
        {
            JOptionPane.showMessageDialog(null, Guess + " is too SMALL!");
            return "NotGuessed";
        }
        else
        {
            JOptionPane.showMessageDialog(null, "Well done! " + Guess +" is correct, it took " + NumGuesses + " goes.");
            return "Guessed";
        }
    }
}
private class T6Ex13GUIin extends JFrame
{
    private JLabel lblGuess;
    private JTextField txfGuess;
    private JButton btnPickNumber;
    private JButton btnQuit;

    private T6Ex13GUIin()
    {//constructor
        Font fontDialog = new Font("Dialog", Font.BOLD,24);
        this.setSize(1000,500);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLocation(100,0);
        this.setTitle("Guessing Game");
        this.setLayout(null);
        lblGuess = new JLabel("Type Guess:");
        lblGuess.setFont(fontDialog);
        lblGuess.setBounds(100,200,200,50);
        lblGuess.setVisible(false);
        this.add(lblGuess);
        txfGuess = new JTextField("");
        txfGuess.setBounds(300,200,100,50);
        txfGuess.setFont(fontDialog);
        txfGuess.setVisible(false);
        ReturnListener MyReturnListener = new ReturnListener();
        txfGuess.addKeyListener(MyReturnListener);
        this.add(txfGuess);
        ClickListener MyClickListener = new ClickListener();
        btnPickNumber = new JButton("Pick Number");
        btnPickNumber.setBounds(100,100,750,50);
        btnPickNumber.setFont(fontDialog);
        btnPickNumber.addActionListener(MyClickListener);
        this.add(btnPickNumber);
        btnQuit = new JButton("Quit");
        btnQuit.setBounds(750,300,100,50);
        btnQuit.setFont(fontDialog);
        btnQuit.addActionListener(MyClickListener);
        this.add(btnQuit);
        this.setVisible(true);
    }
    private class ClickListener implements ActionListener
    {
        private ClickListener()
        {//constructor              
        }
        public void actionPerformed(ActionEvent e)
        {               
            if (e.getSource() == btnPickNumber)
            {
                MyGuessingGame.GenerateNum();
                MyGuessingGame.NumGuesses=0;
                btnPickNumber.setVisible(false);
                lblGuess.setVisible(true);
                txfGuess.setVisible(true);
                txfGuess.setText("");
            }
            if (e.getSource() == btnQuit)
            {
                System.exit(0);
            }
        }
    }
    private class ReturnListener implements KeyListener
    {
        private ReturnListener()
        {//constructor
        }
        public void keyPressed(KeyEvent e)
        {
        }
        public void keyReleased(KeyEvent e)
        {
        }
        public void keyTyped(KeyEvent e)
        {
            if (e.getKeyChar() == '\n')
            {
                MyGuessingGame.Guess = 
                Integer.parseInt(txfGuess.getText());
                if (MyGuessingGame.CheckNum().equals("Guessed"))
                {
                    lblGuess.setVisible(false);
                    txfGuess.setVisible(false);
                    btnPickNumber.setVisible(true);
                }
                else
                {
                    txfGuess.setText("");
                }
            }
        }
    }
}

}

Answer 1

你有没有尝试过任何测试？比如，调试并查看为NumToGuess设置的值是多少？或者只是简单地显示正在设置的值？然后，如果你知道随机数是什么，你可以测试你的逻辑。

根据您的核心逻辑，我在下面运行了这个简单的代码，并没有遇到任何问题。

public static void main(String[] args) {
    int NumToGuess = 1+(int)(20*Math.random());
    int myGuess    = Integer.parseInt("10"); 
    System.out.println("Value is: " + NumToGuess);
    System.out.println("My Guess: " + myGuess);

    if (myGuess > NumToGuess) {
        System.out.println("Too Big");
    }
    else if (myGuess < NumToGuess) {
        System.out.println("Too Small");
    }

}

Answer 2

Math.rand()生成0到1之间的随机数。因此，乘以20可得到0到20之间的独占值。通过使用(int)转换向下舍入，它变为0到19之间，并且通过加1，它变为1-20（含）。是的，您的号码正确生成。但是，您在checkNum()方法的开头再次添加1，这可能是一个问题。希望这会有所帮助。

java中的算术表达式Math.random

2 个答案: