Java - 用户输入 - 错误循环

Question

这是我的 Java 代码:

Scanner userInput = new Scanner(System.in);
while (true) { // forever loop
    try {
        System.out.print("Please type a value: "); // asks user for input
        double n = userInput.nextDouble(); // gets user input as a double
        break; // ends if no error
    }
    catch (Throwable t) { // on error
        System.out.println("NaN"); // not a number
    }
}

您可以从评论中了解这应该做什么。

但是当我输入非数字的内容时，会发生这种情况:

Please type a value: abc
NaN
Please type a value: NaN
Please type a value: NaN
Please type a value: NaN
Please type a value: NaN
Please type a value: NaN
Please type a value: NaN

依此类推，直到我强行停止它。

在Python中我会这样做:

while True:
    try:
        n = float(raw_input("Please type a value: "))
        break
    except Exception:
        print "NaN"

如何在 Java 中执行此操作？我尝试过使用 do while。

Answer 1

调用nextLine() catch block 中的方法。

Advances this scanner past the current line and returns the input that was skipped. This method returns the rest of the current line, excluding any line separator at the end. The position is set to the beginning of the next line.

Since this method continues to search through the input looking for a line separator, it may buffer all of the input searching for the line to skip if no line separators are present.

 catch (InputMismatchException t) { // on error
    userInput.nextLine();
    System.out.println("NaN"); // not a number
  }