How to return arrays in switch-case statement in Java?

Question

The essence of the problem: you need to implement a public static method that returns an array of two elements - the names of the days off in English. The method accepts a parameter as input - the return format as a string. There are two possible values in total:

"long" (default) – array contains the strings "saturday" and "sunday"

"short" - the array contains the strings "sat" and "sun"

The problem needs to be solved using the switch-case statement. My solution is as follows:

class App {
   
  public static void main(String[] args){
      App.getWeekends("long");
  }

    public static void getWeekends(){


     String[] day =new String[4];
     day[0]="saturday";
     day[1]="sunday";
     day[2]="sat";
     day[3]="sun";

     switch(day){
        case "long":
          return {"saturday","sunday"};

        case "short":
          return {"sat", "sun"};

      default:
       return null;    
     }
    }
  
}

ok ... and, isn't it working? why do you have that day array, if you choose not to use it? — Stultuske, Jun 09 '22 at 12:33
Also, `public static void getWeekends(){` You need to add the parameter to the function. — 001, Jun 09 '22 at 12:34

score 2 · Accepted Answer · edited Jun 09 '22 at 12:57

Your code contains multiple unrelated errors.

Array initializers not allowed

{"saturday", "sunday"}

That's not legal java, except in very specific places.

Specifically, in the initializing expression of either a local variable, or field declaration whose type is an array, that is legal, and it isn't legal anywhere else. In other words, okay:

String[] x = {"saturday", "sunday"};

And that's about the only place you can legally write that. If you want an expression that resolves to a string array with 2 'values', the first one being "saturday" and the second being "sunday", you write:

new String[] {"saturday", "sunday"};

This is also legit in variable declarations:

String[] x = new String[] {"saturday", "sunday"};

But you can 'shorten' it and omit the new String[] part there.

Parameter confusion

In your main app you pass "long" as parameter to your getWeekends method, but your getWeekends() method declaration accepts zero parameters. You need to fix that:

public static void getWeekends(String type) {

Return type confusion

You write return in your getWeekends method, i.e. you want to return something. Specifically, you want to return a string array. However, you've declared it to return nothing (void means: I return nothing). You must fix this:

public static String[] getWeekends(String type) {

Pointless creation of `day`

It looks like that whole day thing is you trying random stuff, flailing about and having no idea what to do. Let's just get rid of it? Remove the stuff from String[] day to day[3]=; you can simply switch on type, which is the parameter you got from whatever called you.

Your app does nothing

A return value is just... Returned. To the caller. The caller needs to do something with it. Perhaps, here, as an example, we shall print it. Let's add that to your main method using System.out.println(Arrays.toString(the-array-here)).

`null` confusion

null should not be used unless you really know what you are doing and you have a clear definition of things. It most certainly should not be used as 'stand in' for an error condition. Just throw something if a code path occurs that you don't know how to deal with. The default case should throw something instead of returning null.

Putting it all together

Thus:

class App {
   
  public static void main(String[] args){
      String[] dayNames = App.getWeekends("long");
      System.out.println(Arrays.toString(dayNames));
  }

    public static String[] getWeekends(String type) {
     switch(type) {
        case "long":
          return new String[] {"saturday","sunday"};

        case "short":
          return new String[] {"sat", "sun"};

      default:
          throw new IllegalArgumentException("Pass either 'short' or 'long'");
     }
    }
}

Thanks everyone! I will learn my mistakes in Java!!! – Pete Alexandrovich Jun 09 '22 at 13:28 — Pete Alexandrovich, Jun 09 '22 at 13:28

Alecasa · Answer 2 · 2022-06-09T13:11:29.220

Try this , i also added a scanner so you can type in the console if you want the short version or the long one

You had a void method but you tried to return arrays... void methods can't return values

You can still use the return null; if the input isn't one of the cases

import java.util.Arrays;
import java.util.Scanner;

public class App {
    

        public static void main(String[] args){
            Scanner sc = new Scanner(System.in);
            System.out.println("Write \"long\" for the long format, or \"short\" for the short format");
            String length= sc.next();
            System.out.println(Arrays.toString(getWeekends(length)));
        }

        public static String[] getWeekends(String input){


            switch(input){
                case "long":
                    return new String[] {"saturday","sunday"};

                case "short":
                    return new String[] {"sat", "sun"};

            }
            return new String[0];
        }


}