UnsupportedOperationException while adding a string to a list through ArrayAdapter

Question

What I am trying to do here is add the word currently in the EditText at the press of "Enter/Done" on the softkey. However, each time I press the "Enter/Done" on the soft key, the app crashes.

I've tried to do some debugging and it appears that the issue seems to be the adapter.add(v.getText().toString()); line. I am not sure why/how !!

  public boolean onEditorAction(TextView v,int actionId, KeyEvent event)    {
  Log.d("InThere","in onEditorAction1");
  if((event==NULL) || (event.getAction()==KeyEvent.ACTION_UP))
  {
     if(event==NULL)
     Log.d("InThere","inside if+EVENT");
     if(event.getAction()==KeyEvent.ACTION_UP)
    Log.d("InThere","inside if+ACTION_UP");
     Log.d("InThere","before adapter ");
         adapter.add(v.getText().toString());      <<<cause of error ?
     Log.d("InThere","after adapter ");
     v.setText("");

     InputMethodManager imm=(InputMethodManager)
     getSystemService(INPUT_METHOD_SERVICE);
     imm.hideSoftInputFromWindow(v.getWindowToken(), 0);
  }

  Log.d("InThere","in onEditorAction2");
  return true;

}

I created a filter with the tag "InThere" and here's what it looks like in the LogCat:

InThere         in onEditorAction1
InThere         in onEditorAction2
InThere         in onEditorAction1
InThere         inside if+ACTION_UP
InThere         before adapter

Also, could you help me understand why the string is being obtained through an instance of TextView in the onEditorAction function when actually it is actually being obtained from EditText ?

[UPDATE]

Here's the declaration part of the code....

private final static String[] items={"this","is","a","really","silly","list"};
 private static final KeyEvent NULL = null;
   private ArrayList<String> words=null;
    private ArrayAdapter<String> adapter;

    public void onCreate(Bundle icicle) 
    {
        super.onCreate(icicle);
        words = new ArrayList<String>();
        for(String s: items)
        {
            words.add(s); 
        }
        adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,items);
        setListAdapter(adapter);

    }

Yeah what is the adapter class? Also check your LogCat for the stacktrace, that is the import log to read! Will tell you the exact error — Blundell
– Blundell, Commented Jul 6, 2013 at 14:47
EditText is a subclass of TextView developer.android.com/reference/android/widget/EditText.html — Blundell
– Blundell, Commented Jul 6, 2013 at 14:48
@Blundell or @Wand Maker : Oh! So sorry about that. It's declared as private ArrayAdapter<String> adapter; within the same class i.e MainActivity.java — user2499998
– user2499998, Commented Jul 6, 2013 at 16:04
Use an ArrayList containing the items values and pass that to the ArrayAapter. Otherwise the adapter will create a non mutable list from the array you pass in for which the add/remove methods don't work and throw the error you see. — user
– user, Commented Jul 6, 2013 at 16:45

Blundell · Accepted Answer · 2013-07-06 16:54:05Z

2

Yeah as suspected, your ArrayAdapter is backed by an array.

Array does not support the add operation.

Change it to be back by an ArrayList. ie:

private final static List<String> items = new ArrayList();
static {
  items.add("this");
  items.add("is");
  items.add("a");
  items.add("really");
  items.add("silly");
  items.add("list");
}

As WandMaker hinted, you seem to have done some work to create an ArrayList already, another solution could be:

 adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, words);

The optimum solution (with your code) being:

public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        List<String> words = new ArrayList<String>();
        words.add("this");
        words.add("is");
        words.add("a");
        words.add("really");
        words.add("silly");
        words.add("list");
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, words);
        setListAdapter(adapter);
    }

edited Jul 6, 2013 at 16:54

answered Jul 6, 2013 at 16:46

Blundell

76.8k33 gold badges222 silver badges242 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Wand Maker Over a year ago

I don't understand your answer. Where is it backed by an array? He has words = new ArrayList<String>();

Blundell Over a year ago

@WandMaker no need to -1 just because you don't get it. It is backed by an array here in his question: new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,items);

Wand Maker Over a year ago

But your solution is unnecessarily asking to create a static variable. You can fix the answer by telling him to pass the "words" as parameter instead of "items" I have removed -1, your solution is not right though.

Blundell Over a year ago

@WandMaker it is static in his question!

user2499998 Over a year ago

@Blundell Thank you, it's worked now. It dawned on me after I read your "another solution" part... So from what I understand now, an array cannot be passed on to an ArrayAdapter because it's size cannot be increased at runtime, correct?

|

Collectives™ on Stack Overflow

UnsupportedOperationException while adding a string to a list through ArrayAdapter

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related