如何在任何数字之间找到偶数和奇数？

Question

我正在制作一个程序作为我在 java 中学习的培训，它可以查看用户输入的任何数字之间的偶数和奇数，如果我在开始时输入偶数，它会显示消息的问题

你没有输入偶数

如果用户在开始时输入了一个奇数，我只是希望他首先查看此消息

public static void main(String[] args) {

  isevennumber(1, 5);

}

public static void isevennumber(int startwith, int endwith) {

    for (int i = startwith; i <= endwith; i++) {

        if (i % 2 == 0) {

            System.out.println("you have entered an even number which is " + i);

        } else  {

            System.out.println("you haven't entered an even number");

        }

    }

}

输出是

you haven't entered an even number

you have entered an even number which is 2

you haven't entered an even number

you have entered an even number which is 4

you haven't entered an even number

抱歉有任何错误，这是我在这里的第一篇文章

Answer 1

只需再添加一个if以检查这是否是第一次迭代：public static void isevennumber(int startwith, int endwith) {&nbsp; &nbsp; for (int i = startwith; i <= endwith; i++) {&nbsp; &nbsp; &nbsp; &nbsp; if (i % 2 == 0)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println("you have entered an even number which is " + i);&nbsp; &nbsp; &nbsp; &nbsp; else if (i == startwith)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println("you haven't entered an even number");&nbsp; &nbsp; }}

Answer 2

这里的问题是，每次在循环中数字不是奇数时，它都会打印出您没有输入偶数。你可以这样试试：&nbsp; public static void main(String[] args) {&nbsp; &nbsp; isevennumber(1, 5);&nbsp; }&nbsp; public static void isevennumber(int startwith, int endwith) {&nbsp; &nbsp; &nbsp; List<Integer> evenNumbers = new ArrayList();&nbsp; &nbsp; &nbsp; for (int i = startwith; i <= endwith; i++) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (i % 2 == 0) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; evenNumbers.add(i);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; if (evenNumbers.isEmpty()) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println("you haven't entered an even number");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return;&nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; System.out.println("you have entered the following even numbers " + evenNumbers);&nbsp; }这将打印出：&nbsp;you have entered the following even numbers [2, 4]

Answer 3

您错过了一个步骤，这里的问题是每次循环中数字不是奇数时，它都会打印您没有输入偶数。以下是适合您的正确解决方案。&nbsp; &nbsp; public static void isevennumber(int startwith, int endwith) {&nbsp; &nbsp; &nbsp; &nbsp; for (int i = startwith; i <= endwith; i++)&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (i % 2 == 0)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println("you have entered an even number which is " + i);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; else if (i == startwith)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println("you haven't entered an even number");&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }