creating a chat activity in android

Question

1. After declaring and creating the textWatcher object, I would like to disable the send button and set it to gray if the chatText (edit text) is empty

2. I think it's a problem of ranking. Please help.

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_chat);
   
       list = (ListView)findViewById(R.id.listView);
       list.setTranscriptMode(AbsListView.TRANSCRIPT_MODE_ALWAYS_SCROLL);
       chatText = (EditText)findViewById(R.id.editText);
       //chatText.setOnKeyListener(this);
   
       me = true;
       send = (Button)findViewById(R.id.button);
       change = (Button)findViewById(R.id.button2);
   
   
   
       list.setTranscriptMode(AbsListView.TRANSCRIPT_MODE_ALWAYS_SCROLL);
   
       adp =  new TheAdapter(getApplicationContext(),R.layout.chat);
   
       list.setAdapter(adp);
   
       chatText.addTextChangedListener(textWatcher);
       checkFieldsForEmptyValues();
   
   
       send.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               envoyer();
           }
   
       });
   
       change.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               me = !me;
               if (!me) {
                   change.setText(R.string.sender2);
               } else {
                   change.setText(R.string.sender);
               }
           }
       });
   }
   
   
   
   
   
   public void envoyer(){
   
       adp.add(new messages(me, chatText.getText().toString()));
       chatText.setText("");
   }
   
   private  void checkFieldsForEmptyValues(){
   
       String s1 = chatText.getText().toString();
   
       if (s1.length() < 0 ) {
           send.setEnabled(false);
       } else {
           send.setEnabled(true);
           send.setBackgroundColor(Color.BLUE);
           //send.setBackgroundColor((getResources().getColor(R.color.blue)));
       }
   
   }
   

Answer 1

In the onTextChanged is where you would check to see if the text field is empty:

chatText.addTextChangedListener(new TextWatcher() {
@Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            if (s.length() > 0) { //enable}
            else if (s.length() == 0 { //disable }

In your code, you have if (s1.length() < 0 ) which I don't think will ever be true because the text size will never be less than 0.