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I'm trying to filter the input char of an EditText to allow only valid float value. (e.g. :"12,45", only one comma, ...).

For this, I use the KeyListener (dont confuse with onKeyListener or textChangeListener. I want to prevent the user from entering invalid data).

On Android 2.3.6 and 3.2 the keyListener.filter() and keyListener.getAcceptedChars() are not called and I can introduce any char (not limited to .getAcceptedChars())

I found little documentations about keyListener. If you got a good example or doc, I'm very interested.

Any clue why this is not working ?

What did I do wrong ?

Activity Code sample:

 @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(...); setContentView(R.layout.editTextTest_lyt); ... mEditTextTest = (EditText) findViewById(R.id.editTextTest); mEditTextTest.setKeyListener(new NumberCommaDecimalKeyListenerTest()); ...}

Layout Code sample:

editTextTest_lyt.xml: <EditText android:id="@+id/editTextTest" android:layout_height="fill_parent" android:layout_width="fill_parent" android:layout_weight="1" android:inputType="numberSigned|numberDecimal" android:ems="5" android:maxLength="9" android:maxLines="1" android:gravity="right|center_vertical" android:imeOptions="actionNext"/>

KeyListener Code sample:

public class NumberCommaDecimalKeyListenerTest extends NumberKeyListener { private static final char[] mAccepted = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', ',' }; private static final boolean mSign = true; private static final boolean mDecimal = true; @Override protected char[] getAcceptedChars() { Log.e("LODA", "KeylistenerTest.getAcceptedChars()"); // DONT show up in logs return mAccepted; } public NumberCommaDecimalKeyListenerTest() { super(); Log.e("LODA", "CREATE KeylistenerTest"); // show up in logs } @Override public int getInputType() { Log.e("LODA", "KeylistenerTest.getInputType()"); // show up in logs int contentType = InputType.TYPE_CLASS_NUMBER; if (mSign) { contentType |= InputType.TYPE_NUMBER_FLAG_SIGNED; } if (mDecimal) { contentType |= InputType.TYPE_NUMBER_FLAG_DECIMAL; } return contentType; } @Override public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) { Log.e("LODA", "enter KeylistenerTest.filter"); // DONT show up in logs // My logic will go here... // if user pressed '.', is changed for ',' source = source.toString().replace(".", ","); source = source.toString().replace("6", "9"); CharSequence out = super.filter(source, start, end, dest, dstart, dend); return out; } }
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1 Answer 1

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Looking at the Android docs they state in relation to KeyListener that:

Note that for most cases this interface has been superceded by general soft input methods as defined by InputMethod; it should only be used for cases where an application has its own on-screen keypad and also wants to process hard keyboard events to match it

And for the method getInputType():

If you return TYPE_NULL then no soft keyboard will provided. In other words, you must be providing your own key pad for on-screen input and the key listener will be used to handle input from a hard keyboard.

If you return any other value, a soft input method will be created when the user puts focus in the editor, which will provide a keypad and also consume hard key events. This means that the key listener will generally not be used, instead the soft input method will take care of managing key input as per the content type returned here.

So because you return a content type the KeyListener is ignored. Looks like this isn't possible then or did you find a work around?

Perhaps you could create a custom TextWatcher instead and then set this on the EditText using EditText.addTextChangedListener(TextWatcher textWatcher).?

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3 Comments

looks like I miss understood the keyListener class. (BTW, what does mean "generally not used" ?!?). thanks for this insight.
I think it means that in most cases it will not be used, with the exception being when the return type of getInputType() is TYPE_NULL.
Could be. anyway the doc on this class is not very clear/complet. I will make some test soon.

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