Where & how to use onKey, onkeyDown, onKeyPressed event in android?

Question

hi where to use onKey and onKeyUp / Down event in android.

eg. I have one text. when the user pressed any key, I want to display this symbol in text form. In this case, the event is used (above).

PLEASE explain with EXAMPLE 

Or give another example that will receive the key event and print to edittext or another.

Thanks in advance...

Answer 1

Pls reference the following code

public class Demo extends Activity
 {

    /**
     *  Variables & Objects Declaration
     * 
     */


     EditText  et;

     private static Context CONTEXT;
    /** Called when the activity is first created. */

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
        setContentView(R.layout.main);
        et =(EditText)findViewById(R.id.header_text02);
        }// end of OnCreate

    @Override
    public boolean onKeyDown(View arg0, Editable arg1, int arg2, KeyEvent arg3) {
        // TODO Auto-generated method stub
        Log.v("I am ","KeyDown");
           switch (keyCode) {
                   case KeyEvent.KEYCODE_A:
                   {
                       //your Action code
                       et.setText("A");
                      return true;
                    }
                      case KeyEvent.KEYCODE_B:
                   {
                       //your Action code
                       et.setText("B");
                      return true;
                    }
                   // similarly write for others too
        }



        return true;
    }// End of onKeyDown



    @Override
    public boolean onKeyUp(View arg0, Editable arg1, int arg2, KeyEvent arg3) {
        // TODO Auto-generated method stub
        Log.v("I am ","KeyUp");
            et.setText("KeyUp");
        return true;
    }// End of onKeyUp



}

Answer 2

If you are watching this in an EditText, it is better to use these

editText.addTextChangedListener(new TextWatcher() {
                public void afterTextChanged(Editable s) { 
                    Log.v("TAG", "afterTextChanged");
                }

                public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
                    Log.v("TAG", "beforeTextChanged");
                }

                public void onTextChanged(CharSequence s, int start, int before, int count) {
                    Log.v("TAG", "onTextChanged");
                }
            });