java - 如果不满足 do while 循环条件，如何打印消息

Question

我如何打印一条消息说“错误:您必须输入 0 到 5 之间的数字”，然后允许用户再次输入

 int number;
 do 
  {
     String textinput = JOptionPane.showInputDialog("give me a number between 0 and 5");
     number = Integer.parseInt(textinput);
  } while (!(number >= 0 && number <= 5));

Answer 1

对原始代码改动最少的最简单方法如下:

int number;
do {
    String textinput = JOptionPane.showInputDialog("give me a number between 0 and 5");
    number = Integer.parseInt(textinput);
    if((number < 0) || (number > 5) {
        //show error message
        continue;  //continue isn't absolutely necessary here, but perhaps for readability
    }
} while (!(number >= 0 && number <= 5));

虽然我觉得这有点笨拙和多余，但您实际上是在检查相同的条件两次。我会采用更类似于以下的方法:

int number;
String textinput = JOptionPane.showInputDialog("give me a number between 0 and 5");
while(true) {
    number = Integer.parseInt(textinput);
    if((number >= 0 && number <= 5)) {
        //show error message and prompt for another input
        contine; //As with before, continue isn't necessary here, but could add readability
    } else /*input was good*/ { break; /*exit while loop*/ }
}