我如何比较包含整数的变量

Question

package Tutorial;
import java.util.Scanner;
public class Tutorial {

  public static void main(String[] args) {
  Scanner sc=new Scanner(System.in);
   String name="revolt";
   int password=0123;
   String Name;
   int Password;
   System.out.println("enter name;");
   Name=sc.nextLine();
   if (Name.equals(name)){
   System.out.println("enter password");
   }
   else{
     System.out.println("wrong Name");
   }
   Password=sc.nextInt();
   if (password==Password){
     System.out.println("access granted...");
   }
   else{
     System.out.println("wrong 
Password!");
   }
  }
}

The code doesn't show any error but when I enter password it tells me wrong password even though the password is correct.

Answer 1

You now know what the issue is but, if you are determined to force a User to provide a numerical password (regardless of the order of digits) then make password a String variable and utilize the Scanner#nextLine() method to get User input. Once you have that input, check it using the String#matches() method with a small Regular Expression (regex) to ensure that only numerical digits were supplied, for example:

/* User must enter an all numerical password that is a 
   minimum of 4 digits to a maximum of 18 digits.  */  
String password = "";
while(password.isEmpty()) {
    System.out.println();
    System.out.println("Enter your numerical Password: --> ");
    System.out.print  ("(enter 'q' to quit): --> ");
    password = sc.nextLine().trim();
    if (password.equalsIgnoreCase("Q")) {
        System.out.println("Quitting ... Bye-Bye");
        System.exit(0);
    }
    // Password must be all numerical, 
    // be a minimum of 4 digits in length, 
    // and be a maximum of 18 digits in length.
    if (!password.matches("\\d+") || password.length() < 4 || password.length() > 18) {
        System.err.println("Invalid Password Supplied (" + password + ")!\n"
                + "A password must contain a 'minimum' of at least four (4)\n"
                + "all numerical digits to a 'maximum' of 18 digits! No alpha\n"
                + "characters or whitespaces are allowed!");
        password = "";
    }
}

The Regular Expression \\\\d+ within the String#matches() method checks to make sure that what is now within the password string variable is indeed a string representation of one or more numerical digits from 0 to 9. A password of 0123 would be considered valid however if you were to parse this to Integer or Long for example, the 0 is omitted.