JAVA class array

Question

I am trying to write to code to list all the objects in the class. (Which is working) but I want to get the code to check if there are objects if the player is empty and print out a message to screen if it is. But I cant get it to work. Can anyone assist me please ?

Class

  public void listAll() 
    {
        for (Song a : songs) {
        if(songs.isEmpty())  //cant get this to check if there are songs on the player.
         {
           System.out.print("There are no songs on the playlist");
         }
        else{
             System.out.print(a);
            }
        }
    }

Tester

 keyIn.nextLine(); //clear the buffer of the previous option
                    System.out.print("On player are");
                    player.listAll();
                    break;

No need to check that condition as you are using enhanced for loop. Loop willl automatically terminate when the next element in array is null. — Sanket Makani
– Sanket Makani, Commented Nov 6, 2016 at 12:53

ItamarG3 · Accepted Answer · 2016-11-06 12:52:35Z

3

You are trying to loop through an empty list, so the looped code doesn't happen at all. If you check whether the list is empty outside of the loop, then you get the result you wanted.

public void listAll() {
    if (songs.isEmpty()) // cant get this to check if there are songs on the
    {
        System.out.print("There are no songs on the playlist");
    } else {
        for (Song a : songs) {
            System.out.print(a);
        }
    }

}

answered Nov 6, 2016 at 12:52

ItamarG3

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Comments

Eran · Accepted Answer · 2016-11-06 12:52:57Z

2

If songs is empty, the loop won't be entered. You need to check outside the loop :

public void listAll()  {
    if(songs.isEmpty()) {
        System.out.println("There are no songs on the playlist");
    } else {
        for (Song a : songs) {
            System.out.println(a);
        }
    }
}

answered Nov 6, 2016 at 12:52

Eran

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Comments

Vasu · Accepted Answer · 2016-11-06 13:01:11Z

2

You need to check the condition if(songs.isEmpty()) outside the for loop because if the list is empty, the execution does not go inside the for loop, so your if condition statement will not get executed at all.

public void listAll() 
    {
         //Check this first
         if(songs.isEmpty())
         {
           System.out.print("There are no songs on the playlist");
           return;//It is even more better to return from here itself
         }

        //NOW, use for loop
        //if songs size is zero, execution does not go inside the for loop
        for (Song a : songs) {
             System.out.print(a);
        }
    }

It is even better, if you can use the return statement to go back to the caller (immediately) from the method (like above), which will indicate that there is no need to process the subsequent lines of code in the method.

edited Nov 6, 2016 at 13:01

answered Nov 6, 2016 at 12:53

Vasu

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1 Comment

americanheartbreak Over a year ago

Thank you very much that worked a treat and now can do it for some of the other parts I need :-)

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