Question

 //Infinite Loop To make the program run continuously.
  while (infiniteLoop == 1) { 
     pickedNumber1 = 1+randNum1.nextInt(12);
     pickedNumber2 = 1+randNum2.nextInt(12);

     System.out.println("What is " + pickedNumber1 + " multiplied by " + pickedNumber2 + "?");

     answer = (pickedNumber1 * pickedNumber2);  

     Scanner myScanner = new Scanner(System.in);

     inputAnswer = myScanner.nextInt();

     if (inputAnswer == answer) {
          System.out.println("Well done!");
     } else {
          System.out.println("Please Try Again");
     }
  }

我想知道如何使用hasNextXXX方法进行用户验证。我希望用户只能输入一个整数而不是任何负数或字母字符。

Answer 1

这应该做的工作：

inputAnswer = myScanner.nextInt();
if(inputAnswer < 0) {
    System.out.println("Invalid input, number must be positive");
    continue;
}

Answer 2

尝试这样的事情：

public static void main(String[] args) {
        int inputAnswer;
        int pickedNumber1;
        int pickedNumber2;
        int answer;
        Random randNum1 = new Random();
        while (true) {

            pickedNumber1 = 1 + randNum1.nextInt(12);
            pickedNumber2 = 1 + randNum1.nextInt(12);

            System.out.println("What is " + pickedNumber1 + " multiplied by "
                    + pickedNumber2 + "?");

            answer = (pickedNumber1 * pickedNumber2);

            Scanner myScanner = new Scanner(System.in);
            inputAnswer = -1;
            while (inputAnswer < 0) {
                try
                {
                    System.out.println("Please enter a valid number:");
                    inputAnswer = myScanner.nextInt();
                }catch(Exception e)
                {
                    myScanner.nextLine();
                }
            }

            if (inputAnswer == answer) {
                System.out.println("Well done!");
            } else {
                System.out.println("Please Try Again");
            }
        }
}

基本循环，直到用户输入大于或等于0的有效数字。每次在用户输入循环之前将inputAnswer重置为-1，以便它最终进入循环。使用try catch块来测试非数字答案。

Answer 3

你可以用它首先检查输入是否正确

 if (inputAnswer < 0)
 {
     System.out.println("Wrong input... no. must be greater t hen zero");
 }
 else if (inputAnswer == answer) // check weather input matches the answer
 {
     System.out.println("Well done!");
 }
 else    
 {
     System.out.println("Please Try Again");
 }

Answer 4

您可以执行类似

的操作

     Scanner myScanner = new Scanner(System.in);
     try {
        inputAnswer = myScanner.nextInt();
     } catch (Exception e) {
        System.out.println("Please try again"); //To check if the input is not character since nextInt() throws exception when character is entered. 
        continue; 
     }

     if (inputAnswer == answer) { //This will take care of negative numbers since answer will not be negative
          System.out.println("Well done!");
     } else {
          System.out.println("Please Try Again");
     }

Answer 5

我认为这就是你要找的东西：

Scanner input = new Scanner(System.in);
int val;
if(input.hasNextInt() && (val = input.nextInt()) >= 0)
{
    //do stuff
}
else
{
    //print error message
    //clear out the line
    input.nextLine();
}

Answer 6

试试这个...希望帮助你。

        while (infiniteLoop == 1) {

        int pickedNumber1 = (int) (Math.random() * 12 + 1);
        int pickedNumber2 = (int) (Math.random() * 12 + 1);

        System.out.println("What is " + pickedNumber1 + " multiplied by "
                + pickedNumber2 + "?");
        try{
        int answer = (pickedNumber1 * pickedNumber2);
        Scanner s1 = new Scanner(System.in);
        int inputanswer = s1.nextInt();
            if(answer == inputanswer){
                System.out.println("Well Done!!");
                infiniteLoop=0;

            }else{

                System.out.println("Wrong Answer Try Again.");
            }


        }catch(InputMismatchException e){
            System.out.println("Not a Number");

        }


    }

扫描程序验证Java输入，

6 个答案: