Android Development: How To Use onKeyUp?

Question

I'm new to Android development and I can't seem to find a good guide on how to use an onKeyUp listener.

In my app, I have a big EditText, when someone presses and releases a key in that EditText I want to call a function that will perform regular expressions in that EditText.

I don't know how I'd use the onKeyUp. Could someone please show me how?

Answer 1

The very right way is to use TextWatcher class.

EditText tv_filter = (EditText) findViewById(R.id.filter);

TextWatcher fieldValidatorTextWatcher = 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 (filterLongEnough()) {
                populateList();
            }
        }

        private boolean filterLongEnough() {
            return tv_filter.getText().toString().trim().length() > 2;
        }
    };
    tv_filter.addTextChangedListener(fieldValidatorTextWatcher);

Answer 2

CORRECTION:

For a while, I used a generic onKeyListener. I soon found that my code was being called twice. Once with the key down and once with key up. I now use the following listener and only call the code once. "if (event.getAction() == KeyEvent.ACTION_UP)" is the key.

OnKeyListener keyListener = new OnKeyListener() {

    @Override
    public boolean onKey(View v, int keyCode, KeyEvent event) {
        if (event.getAction() == KeyEvent.ACTION_UP) {
            //do something here
        }
        return false;
    }
};

I found that onKeyUp() is called automatically for every control in the Activity. If this is what you want, add it to the Activity just like you add the onCreate()

Example:

public boolean onKeyUp(int keyCode, KeyEvent event) {
    //do something here
    return false;
};

I know this is a old question, but maybe this will help others with the same issue.