初学Java if选择语句

 import java.util.Scanner;

 public class SubtractionQuiz {
   public static void main(String[] agrs) {
     int number1 = (int)(Math.random() * );
     int number2 = (int)(Math.random() * );

     if (number1 < number2) {
         int temp = number1;
         number1 = number2;
         number2 = temp;
     }

     System.out.print("What is " + number1 + " - " + number2 + "?");
     Scanner input = new Scanner(System.in);
     int answer = input.nextInt();

     if (number1 - number2 == answer)
         System.out.println("You are correct!");
     else
         System.out.println("You are wrong\n" + number1 + " - " + number2 + " should be " + (number1 - number2));

   }
 }