EditText edittext= (EditText)findViewById(R.id.yourEditTextID);
edittext.addTextChangedListener(new TextWatcher() {
public void afterTextChanged(Editable s) {
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
public void onTextChanged(CharSequence s, int start, int before, int count) {
// text is changed
}
});