Changing text in Android on text change causes overflow error

Question

I want to create an application that can transform text the user enters in an EditText widget in real time, and I've added a TextWatcher to allow me to do stuff on text change, but it's causing an overflow error because I'm basically creating an endless loop (onTextChange -> code to change text -> onTextChange -> etc...).

Anyone got an idea on how to get around this issue?

Here's an example

private boolean isEditable = true;
private EditText text;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    text = (EditText) findViewById(R.id.editText1);
    text.addTextChangedListener(new TextWatcher() {

        @Override
        public void afterTextChanged(Editable s) {
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before,
                int count) {
            if (isEditable) {
                isEditable = false;
                styleText(s.toString());
            } else {
                isEditable = true;
            }
        }

    });

}

private void styleText(String completeText) {
    text.setText(completeText + " test");
}

And while the above actually seems to be working, I cannot get it to work with Html.fromHtml();, which is what I intend to use.

EDITED AGAIN

public class Main extends Activity implements TextWatcher {

    private EditText text;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        text = (EditText) findViewById(R.id.editText1);
        text.addTextChangedListener(this);
    }

    @Override
    public void afterTextChanged(Editable s) {
        text.removeTextChangedListener(this);
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count,
            int after) {
        text.addTextChangedListener(this);
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        text.removeTextChangedListener(this);
        text.setText("Test!");
    }
}

It's throwing a StackOverflowException on line 37, which is "text.setText("Test!");"

Maybe set a flag when you're editing to turn your watcher off? — i_am_jorf, Aug 28 '11 at 18:21
I've added some code. @jeffamaphone - I've already done this, and it seems to be working, but not when I set the text using `Html.fromHtml()` — Michell Bak, Aug 28 '11 at 18:26

Nikola Despotoski · Accepted Answer · 2011-08-28T19:59:56.683

EDIT: And works, no exception is thrown:

  txtwt = new TextWatcher(){

            @Override
            public void afterTextChanged(Editable s) {

            Log.i("REACHES AFTER", "YES");

            }

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count,
                    int after) {
                Log.i("REACHES BEFORE", "YES");
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before,
                    int count) {
                text.removeTextChangedListener(txtwt);//after this line you do the editing code 
                text.setText("TEST");
                Log.i("REACHES ON", "YES");
                text.addTextChangedListener(txtwt); // you register again for listener callbacks

            }};
       text = (EditText) findViewById(R.id.editText1);
        text.addTextChangedListener(txtwt);

This is the Logcat proof, when I dramatically pushed keys :

08-28 19:53:21.265: INFO/REACHES BEFORE(492): YES
08-28 19:53:21.276: INFO/REACHES ON(492): YES
08-28 19:53:21.276: INFO/REACHES AFTER(492): YES
08-28 19:53:21.296: INFO/REACHES BEFORE(492): YES
08-28 19:53:21.305: INFO/REACHES ON(492): YES
08-28 19:53:21.305: INFO/REACHES AFTER(492): YES
08-28 19:53:21.745: INFO/REACHES BEFORE(492): YES
08-28 19:53:21.755: INFO/REACHES ON(492): YES
08-28 19:53:21.755: INFO/REACHES AFTER(492): YES
08-28 19:53:21.775: INFO/REACHES BEFORE(492): YES
08-28 19:53:21.785: INFO/REACHES ON(492): YES
08-28 19:53:21.785: INFO/REACHES AFTER(492): YES
08-28 19:53:22.698: INFO/REACHES BEFORE(492): YES
08-28 19:53:22.705: INFO/REACHES ON(492): YES
08-28 19:53:22.705: INFO/REACHES AFTER(492): YES
08-28 19:53:23.855: INFO/REACHES BEFORE(492): YES
08-28 19:53:23.865: INFO/REACHES ON(492): YES
08-28 19:53:23.865: INFO/REACHES AFTER(492): YES
08-28 19:53:24.385: INFO/REACHES BEFORE(492): YES
08-28 19:53:24.395: INFO/REACHES ON(492): YES
08-28 19:53:24.395: INFO/REACHES AFTER(492): YES
08-28 19:53:24.485: INFO/REACHES BEFORE(492): YES
08-28 19:53:24.485: INFO/REACHES ON(492): YES
08-28 19:53:24.485: INFO/REACHES AFTER(492): YES
08-28 19:53:24.515: INFO/REACHES BEFORE(492): YES
08-28 19:53:24.525: INFO/REACHES ON(492): YES
08-28 19:53:24.525: INFO/REACHES AFTER(492): YES
08-28 19:53:24.625: INFO/REACHES BEFORE(492): YES
08-28 19:53:24.635: INFO/REACHES ON(492): YES
08-28 19:53:24.635: INFO/REACHES AFTER(492): YES
08-28 19:53:24.654: INFO/REACHES BEFORE(492): YES
08-28 19:53:24.665: INFO/REACHES ON(492): YES
08-28 19:53:24.665: INFO/REACHES AFTER(492): YES

Thanks, but this just seems to be crashing again with the following error `08-28 20:44:42.710: ERROR/AndroidRuntime(3198): java.lang.StackOverflowError` — Michell Bak, Aug 28 '11 at 18:43
I've edit my answer remove the listener in the `afterTextChange`. Actually, you might need to remove the listener based when you edit the text changed. Lets say if you trigger edits in the `afterTextChanged`, there you remove the listener, thus you prevent for infinite loop in the `TextWatcher` methods. — Nikola Despotoski, Aug 28 '11 at 18:48
It's a line in the code I use to change the text, but all that's doing is setting a new text using `text.setText();` — Michell Bak, Aug 28 '11 at 19:23
Are you sure you have removed the text watcher listener before you do `.setText()` — Nikola Despotoski, Aug 28 '11 at 19:26
Please check the updated question. It wouldn't reach anything after setText(). — Michell Bak, Aug 28 '11 at 19:30
See my edited answer. I tested. I often write the answers by heart. This code does not throws anything. The previous answer did throw — Nikola Despotoski, Aug 28 '11 at 19:54
Errr... For some reason, it doesn't like `Html.fromHtml("a test string");` and crashes :-( Regular text strings work just fine, but it doesn't like Spannable ones. — Michell Bak, Aug 28 '11 at 20:06
Omg, I am so sorry. I accidentally missed something. Thanks, it works without any problems. — Michell Bak, Aug 28 '11 at 20:09
Hmm... try `Html.fromHtml("a test string").toString()` or make your own `Spannable` with pure java. — Nikola Despotoski, Aug 28 '11 at 20:10

bitle · Answer 2 · 2011-08-28T19:52:45.490

private String originalValue;
void onTextChanged(CharSequence text, int start, int before, int after) {
   if (text.toString().equals(originalValue)) {
      // do nothing
   } else {
      //change your text
      originalValue = text.toString();
   }
}

Edited:

public void onTextChanged(CharSequence s, int start, int before, int count) {
       String currentText = s.toString();
       if (currentText.equals(originalValue)) { //the originalValue must be defined outside of the Watcher
          originalValue = styleText(currentText);
          // text.setText(originalValue); //if styleText doesn't do this
       } else {
          return;
       }
}

Changing text in Android on text change causes overflow error

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