EditText, OnKeyListener or TextWatcher (barcode scanning)

Question

I'm using a barcode scanner which inserts barcode string into an EditText in this format "12345\n". Instead of using a search button, I want to trigger the search event by the "\n" character. I used TextEdit's addTextChangedListener and inside that function I'm doing:

protected TextWatcher readBarcode = new TextWatcher() { 
 @Override
 public void onTextChanged(CharSequence s, int start, int before, int count) {
  // TODO Auto-generated method stub

 }

 @Override
 public void beforeTextChanged(CharSequence s, int start, int count,
   int after) {
  // TODO Auto-generated method stub

 }

 @Override
 public void afterTextChanged(Editable s) {
  // TODO Auto-generated method stub
  char lastCharacter = s.charAt(s.length() - 1);

  if (lastCharacter == '\n') {
   String barcode = s.subSequence(0, s.length() - 1).toString();
   searchBarcode(barcode);
  }
 }
};

It works pretty good for the first time, but I also want to clear the EditText after each scan. But it's not possible to do that inside afterTextChanged event because it's going into a recursive loop or something.

Here is the other solution, which is working pretty good:

editBarcode.setOnKeyListener(new OnKeyListener() {

@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
    // TODO Auto-generated method stub
    String barcode = editBarcode.getText().toString();

    if (keyCode == KeyEvent.KEYCODE_ENTER && barcode.length() > 0) {
        editBarcode.setText("");
        searchBarcode(barcode);
        return true;
    }

    return false;
}
});

Actually I'm not sure what is the right way to do it it. Maybe I can use EditText's OnKeyListener event. Any suggestions?

Thanks

where do you clear the text? with your first solution that ends in a endless loop? try to clear it within the if that checks for the last character. if you do it in there it should work i guess. (reason: linebreak will only be there the first time it is called and will not be there when it will be called again because of the clear) — Patrick Boos, Nov 11 '10 at 06:33
How come you are using @Override for onKey(). Isn't it an abstract method? So it shouldn't require an @Override..right? — faizal, Dec 17 '13 at 16:28

score 5 · Accepted Answer · edited Aug 15 '17 at 13:07

If you clear the EditText content in the afterTextChanged(), you shouldn't have an infinite loop.

 @Override 
 public void afterTextChanged(Editable s) { 
  if (s.length > 0) {

      char lastCharacter = s.charAt(s.length() - 1); 

      if (lastCharacter == '\n') { 
       String barcode = s.subSequence(0, s.length() - 1).toString();
       myEditText.setString("");
       searchBarcode(barcode); 
      }
  }

score 4 · Answer 2 · answered Nov 17 '11 at 11:15

Code of @Hrk does not work for me, because method myEditText.setString() does not exist.

Here is one way:

editText.addTextChangedListener(new TextWatcher() {

  ...

  @Override
  public void afterTextChanged(Editable s) {
    if (s.toString().trim().length() == 0)
      return;

    //do your work, then clear the text here
    s.clear();
  }
});

EditText, OnKeyListener or TextWatcher (barcode scanning)

2 Answers2

Linked