如何检查输入的值是否为整数？如果是，则仅执行其余代码

Question

import java.util.*;

public class MainClass {
  public static void main(String[] args) {

System.out.println("Enter the Number you want the Maximum times the Pattern to Print while Increasing 1 each Time :");

boolean isInteger = true;
do {
     Scanner Obj = new Scanner(System.in);
     int a = Obj.nextInt();

       if (a.hasNextInt()) {               // Line 10 : THE Condition i want is to check if INPUT 'a' has a integer Value and execute rest of the code on the condition.
       int i;
             for (i=1;i<=a;i++){
             int j;
                 for (j=1;j<=i;j++) {
                 System.out.println("a");
                 }
                 System.out.println();
             }
         }
         else {
               System.out.println("Please Enter a Integer Value : ");
               isInteger = false;  
               }
    } while (isInteger == false);

  }

}


/*in the Above Code while i was Trying to Print 

*
**
***
**** 

*/

模式类型多次，然后我想通过获取用户输入来执行此操作，并且我想检查用户输入是否是整数，然后仅执行其余代码，否则它应该返回“请输入整数值：”并将用户发送回输入另一个输入 - 我是 Java 新手。

如何检查输入的值是否为整数？ 10号线。

Answer 1

使用 next() 而不是 nextInt() 并检查该值是字符串还是数字以避免默认错误。 尝试这样

        System.out.println("Enter the Number you want the Maximum times the Pattern to Print while Increasing 1 each Time :\n");
        boolean isInteger = true;
        do {
            Scanner Obj = new Scanner(System.in);
            String userInput = Obj.next();
            int number = 0;
            try {
                number = Integer.parseInt(userInput);
                isInteger = true;
            } catch(Exception e) {
                isInteger = false;
            }
            if(isInteger) {
                int i, j;
                for (i = 1; i <= number; i++) {
                    for (j = 1; j <= i; j++) {
                        System.out.print("*");
                    }
                    System.out.println();
                }
            } else {
                System.out.println("Please Enter a Integer Value - " + userInput);
            }
        } while (isInteger == false);