TextWatcher for more than one EditText

I would do it like this:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    EditText e = new EditText(this);
    e.addTextChangedListener(new CustomTextWatcher(e));
}

private class CustomTextWatcher implements TextWatcher {
    private EditText mEditText;

    public CustomTextWatcher(EditText e) { 
        mEditText = e;
    }

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

    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }

    public void afterTextChanged(Editable s) {
    }
}

Suggested solution in @Sebastian Roth's answer is not one instance of TextWatcher for some EditTexts. It is one class and n instances of that class for n EditTexts.

Each EditText has its own Spannable. TextWatcher's events has this Spannable as s parameter. I check their hashCode (unique Id of each object). myEditText1.getText() returns that Spannable. So if the myEditText1.getText().hashCode() equals with s.hashCode() it means that s belongs to myEditText1

So if you want to have one instance of TextWatcher for some EditTexts you should use this:

private TextWatcher generalTextWatcher = new TextWatcher() {    

    @Override
    public void onTextChanged(CharSequence s, int start, int before,
            int count) {

        if (myEditText1.getText().hashCode() == s.hashCode())
        {
            myEditText1_onTextChanged(s, start, before, count);
        }
        else if (myEditText2.getText().hashCode() == s.hashCode())
        {
            myEditText2_onTextChanged(s, start, before, count);
        }
    }

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

        if (myEditText1.getText().hashCode() == s.hashCode())
        {
            myEditText1_beforeTextChanged(s, start, count, after);
        }
        else if (myEditText2.getText().hashCode() == s.hashCode())
        {
            myEditText2_beforeTextChanged(s, start, count, after);
        }
    }

    @Override
    public void afterTextChanged(Editable s) {
        if (myEditText1.getText().hashCode() == s.hashCode())
        {
            myEditText1_afterTextChanged(s);
        }
        else if (myEditText2.getText().hashCode() == s.hashCode())
        {
            myEditText2_afterTextChanged(s);
        }
    }

};

and

myEditText1.addTextChangedListener(generalTextWatcher);
myEditText2.addTextChangedListener(generalTextWatcher);

I use this solution:

• Add method that returns listener:

  private TextWatcher getTextWatcher(final EditText editText) {
      return new TextWatcher() {
          @Override
          public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
  
          }
  
          @Override
          public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
              // do what you want with your EditText
              editText.setText("blabla");
          }
  
          @Override
          public void afterTextChanged(Editable editable) {
  
          }
      };
  }
  

• Add listener to multiple EditText's, you can also pass other parameters:

  editText1.addTextChangedListener(getTextWatcher(editText1));
  editText2.addTextChangedListener(getTextWatcher(editText2));
  editText3.addTextChangedListener(getTextWatcher(editText3));