JOptionPane.showInputDialog的用户输入验证 [英] User input validation for JOptionPane.showInputDialog

问题描述

我正在学习JAVA，并且在代码的这一特定部分遇到了一些麻烦.我搜索了多个站点，并尝试了许多不同的方法，但似乎无法弄清楚如何实现一种适用于不同可能性的方法.

I'm just learning JAVA and having a bit of trouble with this particular part of my code. I searched several sites and have tried many different methods but can't seem to figure out how to implement one that works for the different possibilities.

int playerChoice = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter number for corresponding selection:\n"
                + " (1) - ROCK\n (2) - PAPER\n (3) - SCISSORS\n")) - 1;

我想我即使在用户没有输入以及输入不是1、2或3的情况下，也需要进行某种类型的验证.有人对我如何完成此操作有建议吗?

I imagine I need to have some type of validation even for when the user has no input as well as an input that is not 1, 2 or 3. Anyone have suggestions on how I can accomplish this?

我尝试了while循环，一个if语句，用于在将输入转换为整数之前检查null，以及几种其他类型的if else if方法.

I tried a while loop, an if statement to check for null before converting the input to an integer, as well as a few different types of if else if methods.

提前谢谢！

推荐答案

您需要执行以下操作来处理错误的输入:

You need to do something like this to handle bad input:

boolean inputAccepted = false;
while(!inputAccepted) {
  try {
    int playerChoice = Integer.parseInt(JOption....

    // do some other validation checks
    if (playerChoice < 1 || playerChoice > 3) {
      // tell user still a bad number
    } else {
      // hooray - a good value
      inputAccepted = true;
    }
  } catch(NumberFormatException e) {
    // input is bad.  Good idea to popup
    // a dialog here (or some other communication) 
    // saying what you expect the
    // user to enter.
  }

  ... do stuff with good input value

}

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