How to fix weird formatting when printing arrays, using \t

Question

I'm working on a code which prints an array of locations, either in ascending or descending order. However, the formatting is all wrong for two out of 12 locations.

Code:

import java.util.*;
import static java.lang.System.*;
import java.net.URL;
import java.net.MalformedURLException;
import java.io.*;
class airwaysReservation {
    static Scanner sc = new Scanner(System.in);
    static String src[] = {"Mumbai", "London", "Hiroshima", "Lagos", "Minsk", "Baghdad", "Istanbul", "Delhi", "Fez", "Beijing", "Taipei", "Havana"};
    static String dest[] = {"Hyderabad", "Paris", "Athens", "Alexandria", "Seoul", "Hamburg", "Bengaluru", "Rome", "Montreal", "Saitama", "Philadelphia", "Pune"};
    public static void sortAsc(String arr[]) {
        Arrays.sort(arr);
    }
    public static void sortDesc(String arr[]) {
        //using libraries java.util.Arrays, and java.util.Collections, sorts arrays
        Arrays.sort(arr, Collections.reverseOrder());
    }
    public static void list() {
        out.println("Sources \t Destinations");
        for (int i = 0; i< 12; i++) {
            out.println(src[i] + "\t \t  " + dest[i]);
        }
    }
    public static void main(String[] args) {
        out.println("Welcome \n Would you like to see the sources in ascending, or descending order?");
        // stores ascending or descending for later
        char schoice = sc.next().charAt(0);
        out.println("Would you like to view the destinations in ascending, or descending order?");
        // stores ascending or descending for later
        char dchoice = sc.next().charAt(0);
        switch (schoice) {
            case 'a' : 
            sortAsc(src);
            break;
            case 'd' :
            sortDesc(src);
            break;
            default:
            out.println("Invalid choice");
        }
        switch (dchoice) {
            case 'a' :
            sortAsc(dest);
            break;
            case 'd' :
            sortDesc(dest);
            break;
            default:
            out.println("Invalid choice");
        }
        list();
    }
}

The output for this, choosing ascending and then descending comes out to be:

Sources      Destinations
Baghdad       Seoul
Beijing       Saitama
Delhi         Rome
Fez       Pune
Havana        Philadelphia
Hiroshima         Paris
Istanbul          Montreal
Lagos         Hyderabad
London        Hamburg
Minsk         Bengaluru
Mumbai        Athens
Taipei        Alexandria

I have a feeling this issue is because of different word lengths, however, that doesn't seem to affect the last few lines (eg Minsk and Bengaluru). How would I go about making all the destinations start from the same vertical line? Any help will be appreciated, thanks!

Also https://stackoverflow.com/questions/29370621/java-printing-string-with-fixed-width — Scary Wombat, May 31 '19 at 05:37
@SilviuBurcea, strange thing to say when your answer uses the same approach as the answer from this link. — , May 31 '19 at 05:57
@dyukha this question is more about table formatting. Whilst the solution is similar, it is not the same and it answers a different question. — Silviu Burcea, May 31 '19 at 06:07

score 1 · Answer 1 · answered May 31 '19 at 05:37

Notice it only affects lines where the first word is 8 characters or more. A \t advances to the next tab position, which is usually at a multiple of 8 characters.

To do this correctly you must make a pass over the first words to find the maximum length, then use that when printing to insert the correct number of spaces after every word.

For example, if you determine that the longest first word is 13 characters, and you want to have the second word start in at offset 16 (position 17), you would print the first word in a fixed field of length 16.

Silviu Burcea · Answer 2 · 2019-05-31T05:44:00.860

Have you tried String.format("%-12s %-12s", source, destination) ? This will allocate 12 characters for each string, but if you feel that you need more, go ahead and change each 12 to suit your needs.

Here is what I tried to demo it:

public static void main(String[] args) {
    String [][] arr = {
            { "Sources",      "Destinations" },
            { "Baghdad",       "Seoul" },
            { "Beijing",       "Saitama" },
            { "Delhi",         "Rome" },
            { "Fez",       "Pune" },
            { "Havana",        "Philadelphia" },
            { "Hiroshima",         "Paris" },
            { "Istanbul",          "Montreal" },
            { "Lagos",         "Hyderabad" },
            { "London",        "Hamburg" },
            { "Minsk",         "Bengaluru" },
            { "Mumbai",        "Athens" },
            { "Taipei",        "Alexandria" }
    };
    for (String[] a : arr) {
        System.out.printf("%-12s %-12s \n", a[0], a[1]);
    }
}

Getting output:

Sources      Destinations 
Baghdad      Seoul        
Beijing      Saitama      
Delhi        Rome         
Fez          Pune         
Havana       Philadelphia 
Hiroshima    Paris        
Istanbul     Montreal     
Lagos        Hyderabad    
London       Hamburg      
Minsk        Bengaluru    
Mumbai       Athens       
Taipei       Alexandria

How to fix weird formatting when printing arrays, using \t

2 Answers2