Teneppa
Lurker
Hey! I'm trying to code an application to communicate with the HC-06 (Serial bluetooth module). I'm trying to implement a joystick or more like a touchpad to control robotic arm. I would have used NRF24L01 chip with another microcontroller but I thought I could take a look how to code android; I've always wanted to code for phones but I've never got anything working out of it. Hope someone could help me to begin coding java for android.
Java:
package com.example.teemu.copied;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
//package Android.Arduino.Bluetooth;
public class MainActivity extends Activity
{
TextView myLabel;
EditText myTextbox;
BluetoothAdapter mBluetoothAdapter;
BluetoothSocket mmSocket;
BluetoothDevice mmDevice;
OutputStream mmOutputStream;
InputStream mmInputStream;
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
int counter;
volatile boolean stopWorker;
//NAME THE DEVICE
String BT_NAME = "unnamed";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button openButton = (Button) findViewById(R.id.open);
Button sendButton = (Button) findViewById(R.id.send);
Button closeButton = (Button) findViewById(R.id.close);
Button joystick = (Button) findViewById(R.id.b_joystic);
myLabel = (TextView) findViewById(R.id.label);
myTextbox = (EditText) findViewById(R.id.entry);
joystick.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
int x = (int) event.getRawX();
int y = (int) event.getRawY();
TextView xt = (TextView) findViewById(R.id.x_txt);
TextView yt = (TextView) findViewById(R.id.y_txt);
xt.setText(x);
yt.setText(y);
return true;
}
});
//Open Button
openButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
findBT();
openBT();
} catch (IOException ex) {
}
}
});
//Send Button
sendButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
sendData();
} catch (IOException ex) {
}
}
});
//Close button
closeButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
closeBT();
} catch (IOException ex) {
}
}
});
}
void findBT()
{
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(mBluetoothAdapter == null)
{
myLabel.setText("No bluetooth adapter available");
}
if(!mBluetoothAdapter.isEnabled())
{
Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBluetooth, 0);
}
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if(pairedDevices.size() > 0)
{
for(BluetoothDevice device : pairedDevices)
{
if(device.getName().equals(BT_NAME))
{
mmDevice = device;
break;
}
}
}
myLabel.setText("Bluetooth Device Found");
}
void openBT() throws IOException
{
UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); //Standard SerialPortService ID
mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
mmSocket.connect();
mmOutputStream = mmSocket.getOutputStream();
mmInputStream = mmSocket.getInputStream();
beginListenForData();
myLabel.setText("Bluetooth Opened");
}
void beginListenForData()
{
final Handler handler = new Handler();
final byte delimiter = 10; //This is the ASCII code for a newline character
stopWorker = false;
readBufferPosition = 0;
readBuffer = new byte[1024];
workerThread = new Thread(new Runnable()
{
public void run()
{
while(!Thread.currentThread().isInterrupted() && !stopWorker)
{
try
{
int bytesAvailable = mmInputStream.available();
if(bytesAvailable > 0)
{
byte[] packetBytes = new byte[bytesAvailable];
mmInputStream.read(packetBytes);
for(int i=0;i<bytesAvailable;i++)
{
byte b = packetBytes[i];
if(b == delimiter)
{
byte[] encodedBytes = new byte[readBufferPosition];
System.arraycopy(readBuffer, 0, encodedBytes, 0, encodedBytes.length);
final String data = new String(encodedBytes, "US-ASCII");
readBufferPosition = 0;
handler.post(new Runnable()
{
public void run()
{
myLabel.setText(data);
}
});
}
else
{
readBuffer[readBufferPosition++] = b;
}
}
}
}
catch (IOException ex)
{
stopWorker = true;
}
}
}
});
workerThread.start();
}
void sendData() throws IOException
{
String msg = myTextbox.getText().toString();
msg += "\n";
mmOutputStream.write(msg.getBytes());
myLabel.setText("Data Sent");
}
void closeBT() throws IOException
{
stopWorker = true;
mmOutputStream.close();
mmInputStream.close();
mmSocket.close();
myLabel.setText("Bluetooth Closed");
}
}
Code:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
tools:ignore="TextFields,HardcodedText" >
<TextView
android:id="@+id/label"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Type here:"
android:layout_above="@+id/entry"
android:layout_alignParentStart="true" />
<EditText
android:id="@+id/entry"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="@android:drawable/editbox_background"
android:layout_above="@+id/open"
android:layout_alignParentStart="true"
android:layout_marginBottom="22dp" />
<Button
android:id="@+id/open"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dip"
android:text="Open"
android:layout_alignBaseline="@+id/close"
android:layout_alignBottom="@+id/close"
android:layout_centerHorizontal="true" />
<Button
android:id="@+id/send"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send"
android:layout_marginEnd="26dp"
android:layout_alignBaseline="@+id/open"
android:layout_alignBottom="@+id/open"
android:layout_alignParentEnd="true" />
<Button
android:id="@+id/close"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Close"
android:layout_marginStart="23dp"
android:layout_marginBottom="20dp"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true" />
<Button
android:id="@+id/b_joystic"
android:layout_width="match_parent"
android:layout_height="300dp"
android:layout_alignEnd="@+id/send"
android:layout_alignStart="@+id/close"
android:layout_below="@+id/y_txt"
android:layout_marginTop="14dp"
android:backgroundTint="?android:attr/colorControlNormal"
android:elevation="0dp"
android:visibility="visible" />
<TextView
android:id="@+id/x_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:text="TextView" />
<TextView
android:id="@+id/y_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignEnd="@+id/x_txt"
android:layout_below="@+id/x_txt"
android:text="TextView" />
</RelativeLayout>
utputStream.write(byte[])' on a null object reference