read blank input and even the numeric input-CodePudding

I tried to make a coding about read the value o sign of numers,and also I have to include the blank space as input,I could read and identify the numers' value,but I could read the blank input and give the error (exception in thread "main" java.lang.numberformatexception: for input string: ")

import java.util.Scanner;

public class CheckingSign {
  public static void main (String[] args) {
    Scanner scanner = new Scanner(System.in);
      System.out.print("Enter floating point value: ");
        String number = scanner.nextLine();
        int n = Integer.parseInt(number);


              if ( n > 0 ) {
              System.out.print("DEBUG:the user input is <   "   number   "  >");
              System.out.println("DEBUG:the trimed input is <"   number   ">");
              System.out.println("The sign of the input is 1");
            } else if ( n < 0 ) {
              System.out.print("DEBUG:the user input is <   "   number   "  >");
              System.out.println("DEBUG:the trimed input is <"   number   ">");
              System.out.println("The sign of the input is -1");
            } else {
              System.out.print("DEBUG:the user input is <   "   number   "  >");
              System.out.println("DEBUG:the trimed input is <"   number   ">");
              System.out.println("Encountered blank input.");

            }
     }

}

CodePudding user response：

Surround the parse with a try-catch statement

    Scanner scanner = new Scanner(System.in);
    System.out.print("Enter floating point value: ");
    String number = scanner.nextLine();
    
    try {
        
        float n = Float.parseFloat(number);
        
        if ( n > 0 ) {
          System.out.print("DEBUG:the user input is <   "   number   "  >");
          System.out.println("DEBUG:the trimed input is <"   number   ">");
          System.out.println("The sign of the input is 1");
        } else if ( n < 0 ) {
          System.out.print("DEBUG:the user input is <   "   number   "  >");
          System.out.println("DEBUG:the trimed input is <"   number   ">");
          System.out.println("The sign of the input is -1");
        }
        
    } catch (Exception e) {
        
        System.out.print("DEBUG:the user input is <   "   number   "  >");
        System.out.println("DEBUG:the trimed input is <"   number   ">");
        System.out.println("Encountered blank input.");    
        
    }