Question

public static void main(String[] args) throws IOException {

    InputStreamReader isr = new InputStreamReader(System.in);
    BufferedReader br = new BufferedReader(isr);

    boolean format = false;
    int grades = 0;

    do {
        System.out.println("Enter course mark (0-100): ");

        try {
            String input = br.readLine();
            grades = Integer.parseInt(input);

        } catch (NumberFormatException | IOException e) {
            System.out.println("Error number format!");
        }

    } while (!format);

    if (grades > 100 || grades < 100) {
        System.out.println("Please enter within the range (0-100)");
    }

    System.out.println("Your grades is " + grades);

}

我在这里做错了什么我试图实现这个

输入课程标记（0-100）：qwerty
  输入数据类型错误。
  输入课程标记（0-100）： - 12
  输入[0,100]范围！
  输入课程标记（0-100）：24
  你的成绩是24

Answer 1

更改

do {
    try {
        String input = br.readLine();
        grades = Integer.parseInt(input);
    }
    catch(...) { ... }
} while (!format);

到

do {
    try {
        String input = br.readLine();
        grades = Integer.parseInt(input);
        format = true; // Add this line
    }
    catch(...) { ... } 
    if (grades > 100 || grades < 100) {
        System.out.println("Please enter within the range (0-100)");
        format = false;
    }

} while (!format);

如果执行流程达到format = true;，那么这意味着用户的输入是正确的＆amp;将确保你打破输入循环。

Answer 2

您不需要使用do..while块。可以使用While块本身输出。您也可以像这样更改程序块

public static void main(String[] args) throws IOException 
{
    int grades = 0;
    InputStreamReader isr = new InputStreamReader(System.in);
    BufferedReader br = new BufferedReader(isr)
while((input=br.readLine())!=null)
    {
      try 
          {
           grades = Integer.parseInt(input);
          }
      catch (NumberFormatException | IOException e) 
          {
           System.out.println("Error number format!");
          }
    }

    if (grades > 100 || grades < 100) 
       {
        System.out.println("Please enter within the range (0-100)");
       }

 System.out.println("Your grades is " + grades);

}

用try catch做while循环

2 个答案: