我怎样才能让这个 do while 循环停止而不 "quit" 导致打印输出？

Question

我试过使用这段代码，但每次它运行并且我输入 quit 时，它都会打印出结果，就好像它应该是一个单词而不是结束循环的触发器，然后循环结束。我尝试只放入一个 if then 语句，如果单词被退出，它将结束整个程序，但我无法摆脱条件不等于“退出”的 do while 循环。这是编码。

do
        {
            System.out.println("Enter a word and I will see if, when the first letter is made the last" + '\n' + "and this word is spelled backwards, is the original word. Type quit to end: ");
            word = keyboard.next().toLowerCase();
            
            String newWord = word.substring(1) + word.charAt(0);
            String reverse = "";
        
            for(int wordLength = newWord.length() - 1; wordLength >= 0; wordLength--)
            {
                reverse = reverse + newWord.charAt(wordLength);
            }
        
            if (word.equals(reverse)) {
                System.out.println("You have entered " + word + ". Does this word with it's first letter made the last then spelled in reverse become the original word? Yes!");
            } else {
                System.out.println("You have entered " + word + ". Does this word with it's first letter made the last then spelled in reverse become the original word? No");
            }
        }while (!word.equals("quit"));

一如既往，我感谢任何帮助！

Answer 1

最简单的解决方案是将您的 else 语句替换为 if else 检查单词 quit，因此 if-else 部分如下所示：

if (word.equals(reverse)) {
    System.out.println("You have entered " + word + ". Does this word with it's first letter made the last then spelled in reverse become the original word? Yes!");
} else if(!word.equals("quit")) {
    System.out.println("You have entered " + word + ". Does this word with it's first letter made the last then spelled in reverse become the original word? No");
}

Answer 2

do while 循环仅在到达循环末尾时才检查条件。因此，您的代码中发生的情况是，当 word 设置为“退出”时，它下面的代码仍然运行，直到到达循环结束。

要实现您想要的效果，请尝试此操作，

do
        {
            System.out.println("Enter a word and I will see if, when the first letter is made the last" + '\n' + "and this word is spelled backwards, is the original word. Type quit to end: ");
            word = keyboard.next().toLowerCase();

            if(word.equals("quit")){ break; }

            String newWord = word.substring(1) + word.charAt(0);
            String reverse = "";
        
            for(int wordLength = newWord.length() - 1; wordLength >= 0; wordLength--)
            {
                reverse = reverse + newWord.charAt(wordLength);
            }
        
            if (word.equals(reverse)) {
                System.out.println("You have entered " + word + ". Does this word with it's first letter made the last then spelled in reverse become the original word? Yes!");
            } else {
                System.out.println("You have entered " + word + ". Does this word with it's first letter made the last then spelled in reverse become the original word? No");
            }
        }while (true);

这将导致 for 循环在输入退出时输出文本之前停止。

Answer 3

您可以通过简单的 while loop 来改变这一切。像这样：

   while(true) {
        System.out.println("Enter a word and I will see if, when the first letter is made the last" + '\n' + "and this word is spelled backwards, is the original word. Type quit to end: ");
        word = keyboard.nextLine().toLowerCase();
        if (word.contentEquals("quit")) break;
        
        String newWord = word.substring(1) + word.charAt(0);
        String reverse = "";
    
        for(int wordLength = newWord.length() - 1; wordLength >= 0; wordLength--)
        {
            reverse = reverse + newWord.charAt(wordLength);
        }
    
        if (word.equals(reverse)) {
            System.out.println("You have entered " + word + ". Does this word with it's first letter made the last then spelled in reverse become the original word? Yes!\n");
        } else {
            System.out.println("You have entered " + word + ". Does this word with it's first letter made the last then spelled in reverse become the original word? No\n");
        }
    }

这将运行直到用户输入“退出”。

if (word.contentEquals("quit")) break;

这将打破循环，程序将停止。

我怎样才能让这个 do while 循环停止而不 "quit" 导致打印输出？

How can I get this do while loop to stop without "quit" causing a printout?

java

do-while