MainActivity.java

package com.example.pjc.echoclient;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.codebutler.android_websockets.WebSocketClient;

import org.apache.http.message.BasicNameValuePair;

import java.net.URI;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class MainActivity extends ActionBarActivity {
    WebSocketClient ws;
    ArrayList<String> items;
    ArrayAdapter<String> adapter;

    private class WebsocketHandler extends Handler {
        @Override
        public void handleMessage(Message msg){
            switch(msg.what) {
                case WebsocketListener.MessageType.Connected:
                    onConnected(); break;
                case WebsocketListener.MessageType.Disconnected:
                    onConnected(); break;
                case WebsocketListener.MessageType.Error:
                    onError(msg.getData().getString("data")); break;

                case WebsocketListener.MessageType.Received:
                    onReceived(msg.getData().getString("data")); break;

                default:
                    Log.d("ws", "unexpected message");
            }
        }

        protected void onConnected() {
            Log.d("ws", "connected");

            Toast.makeText(MainActivity.this, "Connected", Toast.LENGTH_SHORT).show();
        }
        protected void onDisconnected() {
            Log.d("ws", "disconnected");

            Toast.makeText(MainActivity.this, "Disconnected", Toast.LENGTH_SHORT).show();
        }
        protected void onReceived(String data) {
            Log.d("ws", "received : " + data);

            items.add(data);
            adapter.notifyDataSetChanged();
        }
        protected void onError(String msg) {
            Log.d("ws", "error : " + msg);
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initUI();
        initWebsocket();
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();

        quitWebsocket();
    }

    protected void initWebsocket() {
        Handler handler = new WebsocketHandler();
        WebSocketClient.Listener listener = new WebsocketListener(handler);

        List<BasicNameValuePair> extraHeaders = Arrays.asList(
            new BasicNameValuePair("Cookie", "some=cookie")
        );

        /* wss://echo.websocket.org */
        ws = new WebSocketClient(
            URI.create(getString(R.string.host)),
            listener, extraHeaders);
        ws.connect();
    }
    protected void quitWebsocket() {
        ws.disconnect();
    }

    protected void initUI(){
        final ListView list = (ListView)findViewById(R.id.listView);
        final TextView text = (TextView)findViewById(R.id.editText);
        final Button btn = (Button)findViewById(R.id.button);

        items = new ArrayList<String>();
        adapter = new ArrayAdapter<String>(
            this, android.R.layout.simple_expandable_list_item_1, items);

        list.setAdapter(adapter);
        list.setChoiceMode(ListView.CHOICE_MODE_NONE);
        list.setTranscriptMode(ListView.TRANSCRIPT_MODE_ALWAYS_SCROLL);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            if(ws.isConnected()) {
                String msg = text.getText().toString();
                text.setText("");
                ws.send(msg);
            }
            }
        });
    }
}

WebsocketListener.java

package com.example.pjc.echoclient;

import android.os.Handler;
import android.os.Message;

import com.codebutler.android_websockets.WebSocketClient;

public class WebsocketListener implements WebSocketClient.Listener {
    public class MessageType{
        public static final int None = 0;
        public static final int Connected = 1;
        public static final int Disconnected = 2;
        public static final int Received = 3;
        public static final int Error = 4;
    };

    Handler handler;

    public WebsocketListener(Handler _handler) {
        handler = _handler;
    }

    protected void throwToMainActivity(int type, String arg){
        Message msg = new Message();
        msg.what = type;
        msg.getData().putString("data", arg);

        handler.sendMessage(msg);
    }
    protected void throwToMainActivity(int type){
        throwToMainActivity(type, null);
    }

    @Override
    public void onConnect() {
        throwToMainActivity(MessageType.Connected);
    }
    @Override
    public void onDisconnect(int code, String reason){
        throwToMainActivity(MessageType.Disconnected);
    }

    @Override
    public void onMessage(String data){
        throwToMainActivity(MessageType.Received, data);
    }

    @Override
    public void onMessage(byte[] data){
        throwToMainActivity(MessageType.Received);
    }

    @Override
    public void onError(Exception error){
        throwToMainActivity(MessageType.Error, error.toString());
    }
}