Question

如何在发生异常时重新扫描扫描仪？考虑在CLI模式下运行此应用程序。

示例：

System.out.print("Define width: ");
    try {
        width = scanner.nextDouble();
    } catch (Exception e) {
        System.err.println("That's not a number!");
        //width = scanner.nextDouble(); // Wrong code, this bring error.
    }

如果用户未输入double类型输入，则抛出错误。但我想在出现错误信息后。应该要求用户再次输入 width 。

怎么做？

Answer 1

如果我理解正确，您希望程序在失败后要求用户重新输入正确的输入。在这种情况下，您可以执行以下操作：

boolean inputOk = false;
while(!inputOk)
{
    System.out.print("Define width: ");
        try {
            width = scanner.nextDouble();
            inputOk = true;
        } catch (Exception e) {
            System.err.println("That's not a number!");
            scanner.next(); // here is to re-enter it.
        }
}

Answer 2

这完美无缺，我已经仔细检查了

        Scanner in;
        double width;

          boolean inputOk = false;
          do
          {

               in=new Scanner(System.in);
              System.out.print("Define width: ");
                  try {
                      width = in.nextDouble();
                      System.out.println("Greetings, That's a number!");
                      inputOk = true;
                  } catch (Exception e) {
                      System.out.println("That's not a number!");
                      in.reset();

                  }
          }
          while(!inputOk);
    }

Answer 3

您可以使用：

System.out.print("Define width: ");

boolean widthEntered = false;

// Repeath loop until width is entered properly
while (!widthEntered) {

    try {

        // Read width
        width = scanner.nextDouble();

        // If there is no exception until here, width is entered properly
        widthEntered = true;

    } catch (Exception e) {
        System.err.println("That's not a number!");
    }
}

扫描程序异常重试

3 个答案: