“猜数字”游戏

#1 楼

import java.util.Random;
import javax.swing.JOptionPane;

/**
 * The "Guess a Number" game
 * */
public class Guess {
    public Guess() {}

    /**
     * Runs the game while playAgain == true
     */ 
    public static void main(String[] args) {
        do {
            int max = getMax();
            int obj = getObjective();
            userGuess(obj, max);
        } while (playAgain());
    }

    private static int getIntFromUser(String text, int min, int max)
    {
        while (true)
        {
            try
            {
                int val = Integer.parseInt(JOptionPane.showInputDialog(text));
                if (min <= val && val <= max)
                    return val;
            }
            catch (NumberFormatException e) { /* As pointed out by ChrisW, it might be worth having something here */}
        }
    }

    /**
     * Asks the user for the max value
     */
    public static void getMax() {
        return getIntFromUser("You will try to guess a number between 1 and \"max\". Set max: ", 1, Integer.MAX_VALUE);
    }

    /**
     * Gets the objective between 1 and "max"
     */
    public static int getObjective() {
        // Please read Simon André Forsberg's comment about this.
        Random rand = new Random();
        return (max == 1) ?
            1 :
            rand.nextInt(max - 1) + 1;
    }

    /**
     * Takes in the user's guess, validates it, and tells them when they win
     */
    public static void userGuess(int obj, int max) {
        int userGuess;
        do {
            userGuess = getIntFromUser("Guess a number between 1 and " + max + ": ", 1, max);
            userWinLose(userGuess, obj);
        } while (userGuess != obj);
    }

    /**
     * Tells the user whether their guess was high, low, or correct
     */
    public static void userWinLose(int guess, int objective) {
        if (guess < objective)
            JOptionPane.showMessageDialog(null, "Too low!");
        else if (guess > objective)
            JOptionPane.showMessageDialog(null, "Too high!");
        else
            JOptionPane.showMessageDialog(null, "You win!");
    }

    /**
     * Asks the user if they want to play again or quit
     */
    public static boolean playAgain() {
        return (getIntFromUser("Enter 0 to quit or 1 to play again", 0, 1) == 1);
    }
}

#2 楼

do {
setMax();
setObjective();
userGuess();
playAgain();
} while (playAgain == true);

catch (NumberFormatException e) {} // don't do this

if (max == 1)                   // no brackets!
    objective = 1;
else                            // no brackets!
    objective = rand.nextInt(max - 1) + 1;

static boolean playAgain; // no access modifier

#3 楼

do {
    ....
} while (playAgain());

rand.nextInt(max) + 1;

#4 楼

#5 楼

private static int getIntFromUser(String text, int min, int max)
{
    // parseInt might throw NumberFormatException
    int val = Integer.parseInt(JOptionPane.showInputDialog(text));
    if (min <= val && val <= max)
        return val;
    else
        throw new IllegalArgumentException("Not an integer between " + min + " and " max);
}

// display error message from caught exception
// return true if the user wants to play again
private static bool getIsContinueAfterError(String errorMessage)
{
    String message = errorMessage + "\n\nDo you want to continue playing?";
    int reply = JOptionPane.showConfirmDialog(null, message, "Error", JOptionPane.YES_NO_OPTION);
    return (reply == JOptionPane.YES_OPTION);
}

public static void main(String[] args) {
    boolean playAgain;
    do {
        try {
            int max = getMax();
            int obj = getObjective();
            userGuess(obj, max);
            playAgain = playAgain();
        }
        catch (NumberFormatException ex)
        {
            playAgain = getIsContinueAfterError("This is not an integer.");
        }
        catch (IllegalArgumentException ex)
        {
            playAgain = getIsContinueAfterError(ex.getMessage());
        }
    } while (playAgain);
}

#6 楼