title: android setKeyListener event not setting the keys as desired
body: <p>Myself trying to enable/disable a textfield using checkbox as,</p>
  
  <pre><code> tv = (EditText) findViewById(R.id.tv);
   cb = (CheckBox) findViewById(R.id.cb);
   tv.setFocusable(false);
   tv.setKeyListener(null);
   tv.setEnabled(false);
  
    cb.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
  
             @Override
              public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                      if(isChecked) {
                          tv.setFocusable(true);
                          tv.setEnabled(true);
                          tv.setKeyListener(new DigitsKeyListener(false, true));
                      } else {
                          tv.setFocusable(false);
                          tv.setEnabled(false);
                          tv.setKeyListener(null);
                      }
                  }
              }
          );
  </code></pre>
  
  <p>The above code is in <code>onCreate</code> method. But even when the checkbox checked, the <code>tv.setKeyListener(new DigitsKeyListener(false, true));</code> doesn't enabling the keys. Where myself missed?</p>