我遇到前导零的问题

Question

I'm attempting to get this to recognize the leading zeros in my program, and I thought using 'String.format("%03d", code);' would take care of it but I'm still not getting the expected result.

import java.util.Scanner;  
import java.io.*;
public class Main{
    public static void main(String args[]){
        Scanner sc =new Scanner(System.in);
        System.out.println("Enter the shipment code :");
        int code = sc.nextInt();
        String.format("%03d", code);
        // fill the code
        if( code ==  111 ){
            System.out.println("All ways");
        }

        else if( code ==  110){
        System.out.println("Airway and Waterway");
        }

        else if( code ==  011){
        System.out.println("Waterway and Roadway");
        }
        else if( code ==  010){
        System.out.println("Waterway");
        }
        else if( code == 101){
        System.out.println("Airway and Roadway");
        }
        else if(code ==  001){
        System.out.println("Roadway");
        }
    }
}

Answer 1

You're doing something wrong here.

011 , 010 , 001 are octal numbers, as they start with a zero.
Also, using String.format is pointless here, as the resulting value is not used.
This might be why your if branches aren't taken into consideration.

final String formattedValue = String.format("%03d", code);

Now you can use formattedValue as a comparison value for your if statements.
Example

if ("111".equals(formattedValue)) { ... }

Note that maybe transforming the int into a String isn't necessary. But in case you insist on doing so, a good practice is to use a constant String as the operand which calls equals(...) .

Answer 2

You're discarding the formatted value. You need to store it in a variable and compare it as string:

String formatted = String.format("%03d", code);
if( formatted.equals("111") ){
    System.out.println("All ways");
}
// ...

Answer 3

Well, String.format("%03d", code) , returns a string , and you are comparing to integers (octal integers, as LppEdd pointed out).

You should store the formatted string to a variable, eg

String formatted = String.format("%03d", code);

and then compare it to Strings in your if/else statements, like so:

if(formatted.equals("011")) {...}

Answer 4

Don't format and remove any leading 0's in the condition and use switch

int code = sc.nextInt();
    // fill the code
switch(code) {
case 111:
    System.out.println("All ways");
    break;
case 110:
    System.out.println("Airway and Waterway");
    break;
case 11:
    System.out.println("Waterway and Roadway");
    break;
case 10:
    System.out.println("Waterway");
    break;
case 101:
    System.out.println("Airway and Roadway");
    break;
case 1:
    System.out.println("Roadway");
    break;
default:
    System.out.println("Unknown code " + code); 
    break;
}