愚蠢的初学者错误隐藏在某处

Question

我正在尝试编写一个经典的初学者代码，我在其中制作一个随机数，然后让用户尝试猜测。我试图通过使用JOptionPane来获得一点乐趣。除了统计用户猜测随机数的次数的变量外，一切都很好。它总是比它应该的值少一个值（如果我第三次尝试就对了，它会说我两次就对了）。我该如何解决这个问题？

第二个问题-我有out.println（randomNum）；在我让用户猜数字之前（这样我就可以作弊了），但直到我猜了一次之后，它才会在控制台中打印出来。怎么了？如有任何帮助，我们将不胜感激！

int randomNum = new Random().nextInt(11); //define random number
    int guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 1-10: "));
    int numGuesses = 1;
    out.println(randomNum); //cheater
    guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 1-10: "));
    while (guess != randomNum) {
        ++numGuesses; //to increase the value of numGuesses by 1 each time the while loop iterates
        guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 1-10: "));
     }
    JOptionPane.showMessageDialog(null, "You got it right after only " + numGuesses + " tries!");
    out.println(numGuesses); //To see if it matches the JOptionPane value

Answer 1

你真的很接近！现在的情况是，在进入while循环之前进行两次猜测，而不是递增numGuesses。程序员经常试图避免重复代码。试试这个：

int randomNum = new Random().nextInt(11); //define random number
int guess = -1; // set it to an invalid value
int numGuesses = 0; // they haven't guessed at all at this point
out.println(randomNum); //cheater
while (guess != randomNum) {
    ++numGuesses; //to increase the value of numGuesses by 1 each time the while loop iterates
    guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 1-10: "));
 }
JOptionPane.showMessageDialog(null, "You got it right after only " + numGuesses + " tries!");
out.println(numGuesses); //To see if it matches the JOptionPane value 

Answer 2

在检查猜测之前，甚至在进入while循环之前，您已经让用户猜测了两次。删除while循环之前的第二个猜测：

int guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 1-10: "));
int numGuesses = 1;
System.out.println(randomNum); //cheater
// Remove the following line!
guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 1-10: "));

Answer 3

不要向用户询问两次随机值

guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 1-10: "));
while (guess != randomNum) {
    //...
    guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 1-10: "));

相反，使用do-while循环，因为您希望他们至少进行一次猜测。。。

int numGuesses = 0;
do {
    numGuesses++;
    guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 1-10: "));
} while (guess != random);

Answer 4

1）在进入while循环之前，您要求用户猜两次数字。由于numGuesses设置为1，并在进入while循环时加1，因此您将偏离1（您要求用户在while循环中第三次猜测数字）。

2） 由于你是在提示用户猜测数字后打印你的"骗子"代码，它只会在猜测后出现。

请注意Random().nextInt(11)也包含0，因此您可能需要将guess初始化为-1，如下例所示：

    int randomNum = new Random().nextInt(11); //Define random number between 0 (inclusive) and 10 (inclusive)
    int guess = -1;
    int numGuesses = 0;
    out.println(randomNum); //Cheater
    while (guess != randomNum) {
        guess = Integer.parseInt(JOptionPane.showInputDialog("Guess a number from 0-10: "));
        numGuesses++; //To increase the value of numGuesses by 1 each time the while loop iterates
     }
    JOptionPane.showMessageDialog(null, "You got it right after only " + numGuesses + " tries!");
    out.println(numGuesses); //To see if it matches the JOptionPane value