NumberFormatException 打印前必要的错误

Question

I'm getting the following results when I run the following section of my code it works well it just appears to print the NumberFormatException before running the do-while loop even though that isn't an option in my code at least not intended. Please help me to understand this error thank you!

Console output: Enter the number of dice to draw (re-roll) - up to 3: 2 Enter the index numbers (0 to 3) separated by a space of the dice you wish to draw: java.lang.NumberFormatException: For input string: "" Try again Enter the index numbers (0 to 3) separated by a space of the dice you wish to draw: 0 1

Rolling the dice...

int[] tempIndex = new int[hands.getDrawNum()]; boolean tryAgain = true;

            do {
                try {
                    System.out.print("Enter the index numbers (0 to 3) separated by a space "
                            + "of the dice you wish to draw: ");
                    
                        String templine = input.nextLine();
                        String[] templineSplit = templine.split(" ");
                    
                    for (int i = 0; i < hands.getDrawNum(); i++) {
                        
                        tempIndex[i] = (Integer.parseInt(templineSplit[i]));
                    }
                    tryAgain = false;
                
                    for (int i = 0; i < hands.getDrawNum(); i++) {
                        if(!((tempIndex[i] >= 0) && (tempIndex[i] <= 3))) {
                        tryAgain = true;
                        throw new IllegalArgumentException();
                        }   
                }   
                }
                catch (InputMismatchException ime) {
                    System.out.println(ime);
                    System.out.println("Try again");
                    tryAgain = false;
                }
                catch (IllegalArgumentException iae) {
                    System.out.println(iae);
                    System.out.println("Try again");
                }
                catch (ArrayIndexOutOfBoundsException aiob) {
                    System.out.println(aiob);
                    System.out.println("Try again");
                    tryAgain = false;
                }
            } while(tryAgain);
            

Answer 1

The NumberFormatException occurs when an attempt is made to convert a string with improper format into a numeric value

The only place where this can happen in your code is here

tempIndex[i] = (Integer.parseInt(templineSplit[i]));

Use a debugger or print out all values in tempIndex to a console to see which one is not a valid number.