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Attempt to invoke virtual method 'java.io.InputStream android.bluetooth.BluetoothSocket.getInputStream()'

I am trying to connect my android app with hc-06 for sending and receiving data purpose, below is the error occur and I've been stuck here from 3 days.
There error occured to me is
Attempt to invoke virtual method 'java.io.InputStreamandroid.bluetooth.BluetoothSocket.getInputStream()'
Kindly somebody solve it or provide me another working code for sending and receiving data through bluetoth hc-06 android app
package infoaryan.in.hc05_bluetooth;
import androidx.appcompat.app.AppCompatActivity;
import android.app.ProgressDialog;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.io.InputStream;
import java.util.UUID;
public class LedControl extends AppCompatActivity {
TextView textView;
Button btn1, btn2, btn3, btn4, btn5, btnDis;
String address = null;
TextView lumn;
private ProgressDialog progress;
BluetoothAdapter myBluetooth = null;
BluetoothSocket btSocket = null;
private boolean isBtConnected = false;
static final UUID myUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
Thread workerThread;
byte[] readBuffer;
int readBufferPosition;
int counter;
volatile boolean stopWorker;
InputStream mmInputStream;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_led_control2);
Intent intent = getIntent();
address = intent.getStringExtra(MainActivity.EXTRA_ADDRESS);
btn1 = findViewById(R.id.button2);
btn2 = findViewById(R.id.button3);
//For additional actions to be performed
btn3 = findViewById(R.id.button5);
btn4 = findViewById(R.id.button6);
btn5 = findViewById(R.id.button7);
btnDis = findViewById(R.id.button4);
lumn = findViewById(R.id.textView2);
textView = findViewById(R.id.textView3);
new LedControl.ConnectBT().execute();
btn1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick (View v) {
sendSignal("1");
}
});
btn2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick (View v) {
sendSignal("0");
}
});
btn3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick (View v) {
sendSignal("3");
}
});
btn4.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick (View v) {
sendSignal("4");
}
});
btn5.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick (View v) {
sendSignal("5");
}
});
btnDis.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick (View v) {
Disconnect();
}
});
beginListenForData();
}
private void sendSignal ( String givenumber ) {
if ( btSocket != null ) {
try {
btSocket.getOutputStream().write(givenumber.getBytes());
} catch (IOException e) {
msg("Error");
}
}
}
private void Disconnect () {
if ( btSocket!=null ) {
try {
btSocket.close();
} catch(IOException e) {
msg("Error");
}
}
finish();
}
private void msg (String s) {
Toast.makeText(getApplicationContext(), s, Toast.LENGTH_LONG).show();
}
private class ConnectBT extends AsyncTask<Void, Void, Void> {
private boolean ConnectSuccess = true;
#Override
protected void onPreExecute () {
progress = ProgressDialog.show(LedControl.this, "Connecting...", "Please Wait!!!");
}
#Override
protected Void doInBackground (Void... devices) {
try {
if ( btSocket==null || !isBtConnected ) {
myBluetooth = BluetoothAdapter.getDefaultAdapter();
BluetoothDevice dispositivo = myBluetooth.getRemoteDevice(address);
btSocket = dispositivo.createInsecureRfcommSocketToServiceRecord(myUUID);
BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
btSocket.connect();
}
} catch (IOException e) {
ConnectSuccess = false;
}
return null;
}
#Override
protected void onPostExecute (Void result) {
super.onPostExecute(result);
if (!ConnectSuccess) {
msg("Connection Failed. Is it a SPP Bluetooth? Try again.");
finish();
} else {
msg("Connected");
isBtConnected = true;
}
progress.dismiss();
}
}
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()
{
textView.setText(data);
}
});
}
else
{
readBuffer[readBufferPosition++] = b;
}
}
}
}
catch (IOException ex)
{
stopWorker = true;
}
}
}
});
workerThread.start();
}
#Override
protected void onResume() {
super.onResume();
}
}

Getting the value from textview

Hello guys I got a code that I do for my project, the code is to get the value of the heartbeat sensor from Arduino to my android phone using Bluetooth. So far it's going well it can send the value to my app without a problem. but the problem now is I want to get the value of it so I can use my algorithm with it, but seems like I got in a pickle now.
Here is the code :
package com.test.aplikasirevisi;
import java.io.IOException;
import java.io.InputStream;
import java.util.UUID;
import android.app.Activity;
import android.app.ProgressDialog;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.text.method.ScrollingMovementMethod;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.ScrollView;
import android.widget.TextView;
import android.widget.Toast;
public class MonitoringScreen extends Activity {
private static final String TAG = "BlueTest5-MainActivity";
private int mMaxChars = 50000;//Default
private UUID mDeviceUUID;
private BluetoothSocket mBTSocket;
private ReadInput mReadThread = null;
private boolean mIsUserInitiatedDisconnect = false;
private TextView mTxtReceive;
private Button mBtnClearInput;
private ScrollView scrollView;
private CheckBox chkScroll;
private CheckBox chkReceiveText;
private boolean mIsBluetoothConnected = false;
private BluetoothDevice mDevice;
private ProgressDialog progressDialog;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_monitoring_screen);
ActivityHelper.initialize(this);
Intent intent = getIntent();
Bundle b = intent.getExtras();
mDevice = b.getParcelable(MainActivity.DEVICE_EXTRA);
mDeviceUUID = UUID.fromString(b.getString(MainActivity.DEVICE_UUID));
mMaxChars = b.getInt(MainActivity.BUFFER_SIZE);
Log.d(TAG, "Ready");
mTxtReceive = (TextView) findViewById(R.id.txtReceive);
chkScroll = (CheckBox) findViewById(R.id.chkScroll);
chkReceiveText = (CheckBox) findViewById(R.id.chkReceiveText);
scrollView = (ScrollView) findViewById(R.id.viewScroll);
mBtnClearInput = (Button) findViewById(R.id.btnClearInput);
mTxtReceive.setMovementMethod(new ScrollingMovementMethod());
mBtnClearInput.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
mTxtReceive.setText("");
}
});
}
private class ReadInput implements Runnable{
private boolean bStop = false;
private Thread t;
public ReadInput() {
t = new Thread(this, "Input Thread");
t.start();
}
public boolean isRunning() {
return t.isAlive();
}
#Override
public void run() {
InputStream inputStream;
try {
inputStream = mBTSocket.getInputStream();
while (!bStop) {
byte[] buffer = new byte[256];
if (inputStream.available() > 0) {
inputStream.read(buffer);
int i;
/*
* This is needed because new String(buffer) is taking the entire buffer i.e. 256 chars on Android 2.3.4 http://stackoverflow.com/a/8843462/1287554
*/
for (i = 0; i < buffer.length && buffer[i] != 0; i++) {
}
final String strInput = new String(buffer, 0, i);
/*
* If checked then receive text, better design would probably be to stop thread if unchecked and free resources, but this is a quick fix
*/
if (chkReceiveText.isChecked()) {
mTxtReceive.post(new Runnable() {
#Override
public void run() {
mTxtReceive.append(strInput);
int txtLength = mTxtReceive.getEditableText().length();
if(txtLength > mMaxChars){
mTxtReceive.getEditableText().delete(0, txtLength - mMaxChars);
System.out.println(mTxtReceive.getText().toString());
}
if (chkScroll.isChecked()) { // Scroll only if this is checked
scrollView.post(new Runnable() { // Snippet from http://stackoverflow.com/a/4612082/1287554
#Override
public void run() {
scrollView.fullScroll(View.FOCUS_DOWN);
}
});
}
}
});
}
}
Thread.sleep(500);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void stop() {
bStop = true;
}
}
private class DisConnectBT extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
}
#Override
protected Void doInBackground(Void... params) {
if (mReadThread != null) {
mReadThread.stop();
while (mReadThread.isRunning())
; // Wait until it stops
mReadThread = null;
}
try {
mBTSocket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
mIsBluetoothConnected = false;
if (mIsUserInitiatedDisconnect) {
finish();
}
}
}
private void msg(String s) {
Toast.makeText(getApplicationContext(), s, Toast.LENGTH_SHORT).show();
}
#Override
protected void onPause() {
if (mBTSocket != null && mIsBluetoothConnected) {
new DisConnectBT().execute();
}
Log.d(TAG, "Paused");
super.onPause();
}
#Override
protected void onResume() {
if (mBTSocket == null || !mIsBluetoothConnected) {
new ConnectBT().execute();
}
Log.d(TAG, "Resumed");
super.onResume();
}
#Override
protected void onStop() {
Log.d(TAG, "Stopped");
super.onStop();
}
#Override
protected void onSaveInstanceState(Bundle outState) {
// TODO Auto-generated method stub
super.onSaveInstanceState(outState);
}
private class ConnectBT extends AsyncTask<Void, Void, Void> {
private boolean mConnectSuccessful = true;
#Override
protected void onPreExecute() {
progressDialog = ProgressDialog.show(MonitoringScreen.this, "Hold on", "Connecting");// http://stackoverflow.com/a/11130220/1287554
}
#Override
protected Void doInBackground(Void... devices) {
try {
if (mBTSocket == null || !mIsBluetoothConnected) {
mBTSocket = mDevice.createInsecureRfcommSocketToServiceRecord(mDeviceUUID);
BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
mBTSocket.connect();
}
} catch (IOException e) {
// Unable to connect to device
e.printStackTrace();
mConnectSuccessful = false;
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
if (!mConnectSuccessful) {
Toast.makeText(getApplicationContext(), "Could not connect to device. Is it a Serial device? Also check if the UUID is correct in the settings", Toast.LENGTH_LONG).show();
finish();
} else {
msg("Connected to device");
mIsBluetoothConnected = true;
mReadThread = new ReadInput(); // Kick off input reader
}
progressDialog.dismiss();
}
}
}
What i want is to get the value of mTxtReceive on this :
int txtLength = mTxtReceive.getEditableText().length();
if(txtLength > mMaxChars){
mTxtReceive.getEditableText().delete(0, txtLength - mMaxChars);
System.out.println(mTxtReceive.getText().toString());
}
I used System.out.println for seeing if i got the value but in the log it didn't show any thing.
So i need you guys wisdom for this any help?

Your view mTextReceive seems to be a TextView and therefore not editable:
private TextView mTxtReceive;
If it's not an EditText (editable) mTxtReceive.getEditableText will return null see docs
and getText should be called instead see docs.
Therefore your condition might always resolve from
if(txtLength > mMaxChars) into if(null > 50000) which is always false (or actually it might even crash before) and therefore your code inside the if-block is never executed
Try:
// recommended for debugging. Check if this is even called and if text length is really longer than max chars
Log.d(TAG, "text length:" + mTxtReceive.getText().length());
int txtLength = mTxtReceive.getText().length();
if(txtLength > mMaxChars){
// not sure what operation you want to do here but leave out for debugging
Log.d(TAG, "text longer than allowed:" + mTxtReceive.getText().toString());
}
Also use Log.d instead of System.out.println since your log might otherwise not be forwarded to Logcat. Also are you sure this block is executed at all? I'd put a Log.d(TAG, "text length:" + mTxtReceive.getText().length()); outside of the condition for debugging purposes. And finally the obvious question would be if the txtLength is even longer than max chars (and that would be quite a long text with 50000 chars). But you can verify that simply with the recommended log outside the block as well.

How to reestablish a Bluetooth connection after I leave an activity in Android Studio?

I am working on a project that can send and receive Strings to and from an Arduino to control and monitor various sensors and lights. I am running into an issue where once I leave the activity that connects to Bluetooth and then return to that same activity after visiting the home activity I am no longer able to send and receive data. The sending and receiving of strings works perfectly until I leave the activity to go to the home activity and come back.
Here is the Java code for the sensor activity:
package com.example.arduinocontrol;
import androidx.appcompat.app.AppCompatActivity;
import androidx.cardview.widget.CardView;
import androidx.localbroadcastmanager.content.LocalBroadcastManager;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
import android.annotation.SuppressLint;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.method.ScrollingMovementMethod;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class uvlight extends AppCompatActivity implements OnClickListener{
private static final int REQUEST_ENABLE_BT = 1;
private CardView uvLight;
//listeners for button presses
Button on, off,clear;
//textbox below buttons
TextView t1,t2,t3;
BluetoothAdapter mBluetoothAdapter;
BluetoothDevice mDevice;
ByteArrayInputStream mSocket;
ConnectedThread mConnectedThread = null;
ConnectThread mConnectThread = null;
#Override
protected void onCreate(Bundle savedInstanceState)
{
//Instantiation
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_uvlight);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (mBluetoothAdapter == null) {
Toast.makeText(getApplicationContext(),"BT not supported!", Toast.LENGTH_SHORT).show();
return;
}
if (!mBluetoothAdapter.isEnabled()) {
//opens a window to ask user to turn on bluetooth
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
for (BluetoothDevice device : pairedDevices) {
mDevice = device;
}
}
mConnectThread = new ConnectThread(mDevice);
mConnectThread.start();
try {
setw();
} catch (Exception e) {
e.printStackTrace();
}
}
#SuppressLint("ClickableViewAccessibility")
private void setw() throws IOException {
//text for bluetooth device details
t1=(TextView)findViewById(R.id.textView3);
t2=(TextView)findViewById(R.id.response);
t2.setMovementMethod(new ScrollingMovementMethod());
String name = mDevice.getName().toString();
try {
t1.setText("Connected to: " + name);
} catch (Exception e) {
e.printStackTrace();
}
//links on and off to their element IDs
on=(Button)findViewById(R.id.uvlighton);
off=(Button)findViewById(R.id.uvlightoff);
clear=(Button)findViewById(R.id.clear);
//clears log text
clear.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
t2.setText("");
}
});
on.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
//sends 'o' char to Arduino
// method to turn on uv light
if(mConnectedThread != null) {
//String sig = "o";
//mConnectedThread.write(sig.getBytes());
int sig = 112;
mConnectedThread.write(sig);
}
}
});
off.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
//method to turn off uv light
if(mConnectedThread != null) {
//String sig1 = "f";
//mConnectedThread.write(sig1.getBytes());
int sig = 113;
mConnectedThread.write(sig);
}
}
});
}
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
//HC-05 unique uuid
private final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
public ConnectThread(BluetoothDevice device) {
BluetoothSocket tmp = null;
mmDevice = device;
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
try {
//creates RFCOMM socket
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
//shows user they are connected
Toast.makeText(getApplicationContext(), "Connected to your Arduino", Toast.LENGTH_SHORT).show();
//displays bt info in text field
} catch (IOException e) {
Toast.makeText(getApplicationContext(), "Unable to connect!", Toast.LENGTH_SHORT).show();
}
mmSocket = tmp;
}
public void run() {
mBluetoothAdapter.cancelDiscovery();
//need the if for this edge case
try {
mmSocket.connect();
} catch (IOException connectException) {
try {
if (mSocket != null) {
mSocket.close();
}
} catch (IOException closeException) {
Toast.makeText(getApplicationContext(), "Unable to connect socket!", Toast.LENGTH_SHORT).show();
}
return;
}
//new connected thread obj
mConnectedThread = new ConnectedThread(mmSocket);
mConnectedThread.start();
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
//Thread for bluetooth process
private class ConnectedThread extends Thread {
//copies bt socket for threading
private final BluetoothSocket mmSocket;
//copies input stream obj for threading
private final InputStream mmInStream;
//copies output stream obj for threading
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
try {
tmpIn = socket.getInputStream();
} catch (IOException e) {
e.printStackTrace();
}
try {
tmpOut = socket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
//reads from Arduino
#Override
public void run() {
byte[] buffer = new byte[1024];
int begin = 0;
int bytes = 0;
while (true) {
try {
bytes += mmInStream.read(buffer, bytes, buffer.length - bytes);
for (int i = begin; i < bytes; i++) {
//end char for a given message from Arduino
if (buffer[i] == "#".getBytes()[0]) {
mHandler.obtainMessage(1, begin, i, buffer).sendToTarget();
begin = i + 1;
if (i == bytes - 1) {
bytes = 0;
begin = 0;
}
}
}
} catch (IOException e) {
break;
}
}
}
//writes to the output stream (in this case the Arduino)
public void write(/*byte[] bytes*/int num) {
try {
Toast.makeText(getApplicationContext(), "sending bytes", Toast.LENGTH_SHORT).show();
mmOutStream.write(num);
} catch (IOException e) {
e.printStackTrace();
}
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
#Override
public void onClick(View v)
{
try
{
}
catch (Exception e)
{
//displays toast message
Toast.makeText(getApplicationContext(),e.getMessage(), Toast.LENGTH_SHORT).show();
}
}
//Suppresses an annoying handler lear warning
#SuppressLint("HandlerLeak")
Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
byte[] writeBuf = (byte[]) msg.obj;
int begin = (int)msg.arg1;
int end = (int)msg.arg2;
switch(msg.what) {
case 1:
String writeMessage = new String(writeBuf);
writeMessage = writeMessage.substring(begin, end);
//sends message to homepage to turn cardview red
//string called error contains value of writeMessage
Intent intent = new Intent("errorCode").putExtra("error", writeMessage);
LocalBroadcastManager.getInstance(uvlight.this).sendBroadcast(intent);
//write message to the scrolling textbox
t2.append(writeMessage);
break;
}
}
};
}
Here is the Java code for the home activity:
package com.example.arduinocontrol;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.cardview.widget.CardView;
import androidx.localbroadcastmanager.content.LocalBroadcastManager;
public class HomeActivity extends AppCompatActivity implements View.OnClickListener {
private CardView airPump, flowMeter, humiditySensor, levelSwitch1, levelSwitch2, lightStrip, phMeter, uvLight, waterPump, solenoidValve, nutrientPump;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
//defines cards
airPump = (CardView) findViewById(R.id.airpump);
flowMeter = (CardView) findViewById(R.id.flowmeter);
humiditySensor = (CardView) findViewById(R.id.humiditysensor);
levelSwitch1 = (CardView) findViewById(R.id.levelswitch1);
levelSwitch2 = (CardView) findViewById(R.id.levelswitch2);
lightStrip = (CardView) findViewById(R.id.lightstrip);
phMeter = (CardView) findViewById(R.id.phmeter);
uvLight = (CardView) findViewById(R.id.uvlight);
waterPump = (CardView) findViewById(R.id.waterpump);
solenoidValve = (CardView) findViewById(R.id.solenoidvalve);
nutrientPump = (CardView) findViewById(R.id.nutrientpump);
//click listeners
airPump.setOnClickListener(this);
flowMeter.setOnClickListener(this);
humiditySensor.setOnClickListener(this);
levelSwitch1.setOnClickListener(this);
levelSwitch2.setOnClickListener(this);
lightStrip.setOnClickListener(this);
phMeter.setOnClickListener(this);
uvLight.setOnClickListener(this);
waterPump.setOnClickListener(this);
solenoidValve.setOnClickListener(this);
nutrientPump.setOnClickListener(this);
LocalBroadcastManager.getInstance(this).registerReceiver(mReceiver, new IntentFilter("errorCode"));
}
//turns Uvlight card red when an error is sent
private BroadcastReceiver mReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String errorMsg = intent.getStringExtra("error");
if (errorMsg.equals("-3")){
uvLight.setCardBackgroundColor(0xFFFF0000);
}
}
};
#Override
public void onBackPressed() {
moveTaskToBack(true);
}
#Override
public void onClick(View v) {
Intent i;
//on click opens the new activity
switch(v.getId()){
case R.id.airpump : i = new Intent(this,Airpump.class); startActivity(i); break;
case R.id.flowmeter : i = new Intent(this,Flowmeter.class); startActivity(i); break;
case R.id.humiditysensor : i =new Intent(this,Humiditysensor.class); startActivity(i); break;
case R.id.levelswitch1 : i = new Intent(this,Levelswitch1.class); startActivity(i); break;
case R.id.levelswitch2 : i = new Intent(this,Levelswitch2.class); startActivity(i); break;
case R.id.lightstrip : i = new Intent(this,Lightstrip.class); startActivity(i); break;
case R.id.phmeter : i = new Intent(this,Phmeter.class); startActivity(i); break;
case R.id.uvlight : i = new Intent(this,uvlight.class); startActivity(i); break;
case R.id.waterpump : i = new Intent(this,Waterpump.class); startActivity(i); break;
case R.id.solenoidvalve : i = new Intent(this,solenoidvalve.class); startActivity(i); break;
case R.id.nutrientpump : i = new Intent(this,Nutrientpump.class); startActivity(i); break;
default:break;
}
}
}
I am new to Android Studio and this is the first time I have had to make a multi-threaded application. Thank You.

you can try to extract the Bluetooth connection method into a simple profit class, similar to "local broadcast manager". When "uvlight" on destroy Bluetooth connection will continue to open. Or you can refer to GitHub's excellent open source libraries, such as: https://github.com/akexorcist/BluetoothSPPLibrary 。 I believe you can learn more in it

Implementing next button in audio player android

I have been trying to implement next song button in my audio player app. I copied some code from a tutorial but its not working.The button for next song is btnNext and the method is cde(), its the last method in the code. The button gets clicked but next song is not played, current song keeps playing.How do I fix this ?
package com.example.dell_1.myapp3;
import android.app.Activity;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.media.MediaMetadataRetriever;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import static android.R.attr.path;
public class PlayListActivity extends Activity {
private String[] mAudioPath;
private MediaPlayer mMediaPlayer;
private String[] mMusicList;
int currentPosition = 0;
private List<String> songs = new ArrayList<>();
MediaMetadataRetriever metaRetriver;
byte[] art;
ImageView album_art;
TextView album;
TextView artist;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_play_list);
mMediaPlayer = new MediaPlayer();
ListView mListView = (ListView) findViewById(R.id.list);
mMusicList = getAudioList();
ArrayAdapter<String> mAdapter = new ArrayAdapter<>(this,
android.R.layout.simple_list_item_1, mMusicList);
mListView.setAdapter(mAdapter);
mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> arg0, View view, int arg2,
long arg3) {
try {
playSong(mAudioPath[arg2]);
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
});
}
private String[] getAudioList() {
final Cursor mCursor = getContentResolver().query(
MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
new String[]{MediaStore.Audio.Media.DISPLAY_NAME, MediaStore.Audio.Media.DATA}, null, null,
"LOWER(" + MediaStore.Audio.Media.TITLE + ") ASC");
int count = mCursor.getCount();
String[] songs = new String[count];
mAudioPath = new String[count];
int i = 0;
if (mCursor.moveToFirst()) {
do {
songs[i] = mCursor.getString(mCursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DISPLAY_NAME));
mAudioPath[i] = mCursor.getString(mCursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DATA));
i++;
} while (mCursor.moveToNext());
}
mCursor.close();
return songs;
}
private void playSong(String path) throws IllegalArgumentException,
IllegalStateException, IOException {
setContentView(R.layout.activity_android_building_music_player);
Log.d("ringtone", "playSong :: " + path);
mMediaPlayer.reset();
mMediaPlayer.setDataSource(path);
//mMediaPlayer.setLooping(true);
mMediaPlayer.prepare();
mMediaPlayer.start();
acv(path);
abc();
cde();
}
public void acv(String path) {
getInit();
metaRetriver = new MediaMetadataRetriever();
metaRetriver.setDataSource(path);
try {
art = metaRetriver.getEmbeddedPicture();
Bitmap songImage = BitmapFactory.decodeByteArray(art, 0, art.length);
album_art.setImageBitmap(songImage);
album.setText(metaRetriver
.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ALBUM));
artist.setText(metaRetriver
.extractMetadata(MediaMetadataRetriever.METADATA_KEY_ARTIST));
} catch (Exception e) {
album_art.setBackgroundColor(Color.GRAY);
album.setText("Unknown Album");
artist.setText("Unknown Artist");
}
}
public void getInit() {
album_art = (ImageView) findViewById(R.id.coverart1);
album = (TextView) findViewById(R.id.Album);
artist = (TextView) findViewById(R.id.artist_name);
}
public void abc() {
ImageButton btnPlay1 = (ImageButton) findViewById(R.id.btnPlay1);
btnPlay1.setBackgroundColor(Color.TRANSPARENT);
btnPlay1.setOnClickListener(
new View.OnClickListener() {
public void onClick(View v) {
if (mMediaPlayer.isPlaying()) {
mMediaPlayer.pause();
} else {
mMediaPlayer.start();
}
}
});
}
public void cde() {
ImageButton btnNext = (ImageButton) findViewById(R.id.btnNext); //this is the button for playing next song.
btnNext.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
try {
currentPosition=currentPosition+1;
playSong(path + songs.get(currentPosition));
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
}
}

Add this in onCreate method:
Bundle bundle = getIntent().getExtras();
position = bundle.getInt("position");
And change next button listener to
btnNext.setOnClickListener(new View.OnClickListener() //this is the button
#Override
public void onClick(View arg0) {
if (mMediaPlayer!= null && mMediaPlayer.isPlaying()) {
mMediaPlayer.stop();
}
uri = Uri.parse(mAudioPath[position + 1]);
mMediaPlayer.setDataSource(getApplicationContext(), uri);
mMediaPlayer.prepare();
mMediaPlayer.start();
}
});

int currentPosition = 0;
if (++currentPosition >= songs.size()) {
currentPosition = 0;
} else
try {
playSong(path + songs.get(currentPosition));
} catch (IOException ex) {
ex.printStackTrace();
}
}
The above code is your code from the onClick method.
As you can see, you are initializing the currentPosition inside onClick.
So to show you what this implies:
onClick -> position = 0 -> position++ (position = 1) -> playSong(songUri)
When you want:
onClick -> position++ -> playSong(songUri)
So, before setting the onCLickListener, you add:
currentPosition = 0;
currentPosition is declared in the class now, so make sure you add it. It should look like this:
int currentPosition;
..other code
public void cde(){
..code here
currentPosition = 0;
... set onClickListener
}
Remove int currentPosition = 0; from the onClick method.
I assume there is a position 0 as well. Here is the refactored code that would handle that:
try {
playSong(path + songs.get(currentPosition));
if (++currentPosition >= songs.size()) {
currentPosition = 0;
}
} catch (IOException ex) {
ex.printStackTrace();
}
The above code is addressing another issue you would be likely to meet. Song 0 would never play on the first round.
Another thing you want to check for (not giving you the code for it as it is easy) is to not play or allow next song if there are no songs. If songs.size == 0 it would never play but set the position to 0 over and over.

Updating the UI upon receiving an android push notification

I have a query regarding android push notification and i had asked it in another stackoverflow post and i did not get much help out of it [Query regarding Android push notifications. So i am posting it again, and it is as follows:
I have an android app that receives push notifications from Google push notification service. When i tap on the received notification, it opens an UI which displays this message, it is a list view. Now, when the user receives the push notification, and assuming that this screen is open, the UI should be refreshed automatically, such that it displays the latest notification. Could anybody let me know how i can solve this?
Below is my code that i have implemented:
Java code to receive the notification:
import java.util.Timer;
import java.util.TimerTask;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.PowerManager;
import android.util.Log;
import com.example.foodu.R;
import com.google.android.gcm.GCMBaseIntentService;
public class GCMIntentService extends GCMBaseIntentService {
private static final String TAG = "GCM ::Service";
// Use your PROJECT ID from Google API into SENDER_ID
public static final String SENDER_ID = "53340195486";
public GCMIntentService() {
super(SENDER_ID);
}
#Override
protected void onError(Context arg0, String errorId) {
Log.e(TAG, "onError: errorId=" + errorId);
}
#Override
protected void onMessage(Context context, Intent data) {
String message;
// Message from PHP server
message = data.getStringExtra("message");
// Open a new activity called GCMMessageView
Intent intent = new Intent(this, com.example.foodu.Notification.class);
// Pass data to the new activity
intent.putExtra("message", message);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
// Starts the activity on notification click
PendingIntent pIntent = PendingIntent.getActivity(this, 0, intent,
PendingIntent.FLAG_UPDATE_CURRENT);
// Create the notification with a notification builder
Notification notification = new Notification.Builder(this)
.setSmallIcon(R.drawable.ic_logo)
.setWhen(System.currentTimeMillis())
.setContentTitle("Deals")
.setContentText(message).setContentIntent(pIntent)
.getNotification();
// Remove the notification on click
notification.flags |= Notification.FLAG_AUTO_CANCEL;
NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
manager.notify(R.string.app_name, notification);
{
// Wake Android Device when notification received
PowerManager pm = (PowerManager) context
.getSystemService(Context.POWER_SERVICE);
final PowerManager.WakeLock mWakelock = pm.newWakeLock(
PowerManager.FULL_WAKE_LOCK
| PowerManager.ACQUIRE_CAUSES_WAKEUP, "GCM_PUSH");
mWakelock.acquire();
// Timer before putting Android Device to sleep mode.
Timer timer = new Timer();
TimerTask task = new TimerTask() {
public void run() {
mWakelock.release();
}
};
timer.schedule(task, 5000);
}
}
#Override
protected void onRegistered(Context arg0, String registrationId) {
Log.i(TAG, "onRegistered: registrationId=" + registrationId);
}
#Override
protected void onUnregistered(Context arg0, String registrationId) {
Log.i(TAG, "onUnregistered: registrationId=" + registrationId);
}
}
The code for the corresponding activity that would be launched when the user taps on the notification:
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.text.SimpleDateFormat;
import java.util.LinkedList;
import java.util.Locale;
import java.util.StringTokenizer;
import java.util.TimeZone;
import com.example.foodu.R;
import com.example.foodu.R.drawable;
import com.example.foodu.R.id;
import com.example.foodu.R.layout;
import com.example.foodu.R.menu;
import com.google.android.gcm.GCMRegistrar;
import android.support.v7.app.ActionBarActivity;
import android.app.AlertDialog;
import android.content.ClipData;
import android.content.ClipboardManager;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.provider.CalendarContract;
import android.util.Log;
import android.view.ActionMode;
import android.view.ActionMode.Callback;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class Notification extends ActionBarActivity {
LinkedList<NotificationData> notificationList = new LinkedList<NotificationData>();
ListView listView = null;
NotificationListAdapter adaptor;
ActionMode mActionMode;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_notification);
overridePendingTransition(R.anim.trans_left_in, R.anim.trans_left_out);
listView = (ListView) findViewById(R.id.listView1);
// Retrive the data from GCMIntentService.java
Intent i = getIntent();
String message = i.getStringExtra("message");
//getDataForDisplay();
if(message!=null)
{
parseData(message);
}else{
getDataToDisplay();
}
adaptor = new NotificationListAdapter(getApplicationContext(), notificationList);
listView.setAdapter(adaptor);
TextView emptyText = (TextView) findViewById(R.id.empty);
emptyText.setText("No Events Yet!");
listView.setEmptyView(emptyText);
listView.setOnItemLongClickListener(new OnItemLongClickListener() {
public boolean onItemLongClick(AdapterView<?> parent, View view,
int position, long id) {
onListitemSelect(position);
view.setSelected(true);
return true;
}
});
}
#Override
protected void onStart() {
// TODO Auto-generated method stub
super.onStart();
adaptor.notifyDataSetChanged();
}
#Override
protected void onRestart() {
// TODO Auto-generated method stub
super.onRestart();
}
void writeToFile(){
FileOutputStream fos;
try {
fos = openFileOutput("varun", Context.MODE_PRIVATE);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(notificationList);
oos.close();
}catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
void readFromFile(){
try{
FileInputStream fis = openFileInput("varun");
ObjectInputStream ois = new ObjectInputStream(fis);
LinkedList<NotificationData> local = (LinkedList<NotificationData>) ois.readObject();
ois.close();
for (int i = 0; i < local.size(); i++) {
notificationList.add(local.get(i));
}
}catch(Exception e){
e.printStackTrace();
}
}
private void getDataToDisplay() {
// TODO Auto-generated method stub
readFromFile();
}
private void parseData(String message) {
try {
int len = 0;
String[] stringArr = new String[100];
StringTokenizer st = new StringTokenizer(message, ".");
len = st.countTokens();
for (int i = 0; i < len; i++) {
if (st.hasMoreTokens()) {
stringArr[i] = st.nextToken();
}
}
NotificationData data = new NotificationData();
data.title = stringArr[0];
data.venue = stringArr[1];
data.date = stringArr[2];
data.time = stringArr[3];
notificationList.add(data);
readFromFile();
} catch (Exception e) {
e.printStackTrace();
}
}
private void getDateToDisplay() {
// TODO Auto-generated method stub
}
#Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
writeToFile();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.notificationmenu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
if(id == R.id.action_register){
registerDevice();
return true;
}
return super.onOptionsItemSelected(item);
}
private void registerDevice() {
try {
GCMRegistrar.checkDevice(this);
GCMRegistrar.checkManifest(this);
GCMRegistrar
.register(Notification.this, GCMIntentService.SENDER_ID);
} catch (Exception e) {
e.printStackTrace();
}
}
private ActionMode.Callback mActionModeCallback = new ActionMode.Callback() {
#Override
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
MenuInflater inflater = mode.getMenuInflater();
inflater.inflate(R.menu.notificationcontext, menu);
return true;
}
#Override
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
return false;
}
#Override
public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_calender:
addToCalender();
mode.finish();
return true;
case R.id.menu_delete:
//deleteData();
showAlertBox();
return false;
case R.id.menu_share:
shareDate();
mode.finish();
return true;
case R.id.menu_copy:
copyToClip();
mode.finish();
return true;
default:
return false;
}
}
#Override
public void onDestroyActionMode(ActionMode mode) {
mActionMode = null;
adaptor.removeSelection();
}
};
void onListitemSelect(int position) {
adaptor.toggleSelection(position);
boolean hasCheckedItems = adaptor.getSelectedCount() > 0;
if (hasCheckedItems && mActionMode == null) {
mActionMode = startActionMode((Callback) mActionModeCallback);
} else if (!hasCheckedItems && mActionMode != null) {
mActionMode.finish();
}
if (mActionMode != null)
mActionMode.setTitle(String.valueOf(adaptor.getSelectedCount()));
}
protected void showAlertBox() {
// TODO Auto-generated method stub
AlertDialog.Builder builder1 = new AlertDialog.Builder(Notification.this);
builder1.setMessage("Delete " + adaptor.getSelectedIds().size()+ " events?");
builder1.setCancelable(true);
builder1.setIcon(R.drawable.alert);
builder1.setTitle("Caution");
builder1.setIcon(android.R.drawable.ic_dialog_alert);
builder1.setPositiveButton("Yes",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
deleteData();
mActionMode.finish();
}
});
builder1.setNegativeButton("No",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
AlertDialog alert11 = builder1.create();
alert11.show();
}
protected void copyToClip() {
StringBuilder shareText = new StringBuilder();
for (int i = 0; i < adaptor.getSelectedIds().size(); i++) {
NotificationData data = notificationList
.get(adaptor.getSelectedIds().keyAt(i));
shareText.append(data.title + " " + data.venue + " " + data.date
+ " " + data.time);
shareText.append("\n");
}
ClipboardManager clipboard = (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE);
ClipData clip = ClipData.newPlainText("Notification App", shareText);
clipboard.setPrimaryClip(clip);
Toast.makeText(getApplicationContext(), "Data copied to ClipBoard",
Toast.LENGTH_LONG).show();
}
protected void shareDate() {
StringBuilder shareText = new StringBuilder();
for (int i = 0; i < adaptor.getSelectedIds().size(); i++) {
NotificationData data = notificationList
.get(adaptor.getSelectedIds().keyAt(i));
shareText.append(data.title + " " + data.venue + " " + data.date
+ " " + data.time);
shareText.append("\n");
}
String share = shareText.toString();
Intent sendIntent = new Intent();
sendIntent.setAction(Intent.ACTION_SEND);
sendIntent.putExtra(Intent.EXTRA_TEXT, share);
sendIntent.setType("text/plain");
startActivity(sendIntent);
}
protected void deleteData() {
int count = 0;
int startPoint = adaptor.getSelectedIds().keyAt(0);
for (int i = 0; i < adaptor.getSelectedIds().size(); i++) {
adaptor.remove(notificationList.get(startPoint));
count++;
}
String message = " Event";
if(count>1)
{
message = " Events";
}
Toast.makeText(getApplicationContext(),
count + message+" deleted", Toast.LENGTH_LONG)
.show();
}
private void addToCalender() {
try {
int count = 0;
for (int i = 0; i < adaptor.getSelectedIds().size(); i++) {
NotificationData data = notificationList
.get(adaptor.getSelectedIds().keyAt(i));
ContentResolver cr = getApplicationContext()
.getContentResolver();
ContentValues values = new ContentValues();
String myDate = data.date + " " + data.time;
String timeArr[] = data.time.split("to");
SimpleDateFormat sfd = new SimpleDateFormat(
"' Date: 'MM/dd/yyyy 'Time: 'hh a", Locale.getDefault());
long time = sfd.parse(myDate).getTime();
values.put(CalendarContract.Events.DTSTART, time);
if (timeArr.length > 0) {
String endTime = timeArr[1];
SimpleDateFormat timeFormat = new SimpleDateFormat(
"' Date: 'MM/dd/yyyy hh a", Locale.getDefault());
long endtime = timeFormat.parse(data.date + " " + endTime)
.getTime();
values.put(CalendarContract.Events.DTEND, endtime);
}
values.put(CalendarContract.Events.TITLE, data.title);
values.put(CalendarContract.Events.DESCRIPTION, data.venue);
TimeZone timeZone = TimeZone.getDefault();
values.put(CalendarContract.Events.EVENT_TIMEZONE,
timeZone.getID());
values.put(CalendarContract.Events.CALENDAR_ID, 1);
Uri uri = cr
.insert(CalendarContract.Events.CONTENT_URI, values);
count++;
}
String message = " Event";
if(count>1)
{
message = " Events";
}
Toast.makeText(getApplicationContext(),
count + message + " added to Calender", Toast.LENGTH_LONG)
.show();
} catch (Exception e) {
e.printStackTrace();
}
}
}

Use LocalBroadcastManager
Check following code / steps
1) Add in your activity (UI refresh Activity)
private BroadcastReceiver mMyBroadcastReceiver;
Then ,
2) In onResume
#Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
mMyBroadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent)
{
// Here you can refresh your listview or other UI
Toast.makeText(getApplicationContext(), "Receiver", 2000).show();
}
};
try {
LocalBroadcastManager.getInstance(this).registerReceiver(mMyBroadcastReceiver,new IntentFilter("your_action"));
} catch (Exception e)
{
// TODO: handle exception
e.printStackTrace();
}}
// and your other code
3) Then unregister in onPause
#Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
LocalBroadcastManager.getInstance(this).unregisterReceiver(mMyBroadcastReceiver);
}
4) Finally add in your GCM reciver class.
first check your activity is Visible or not using static variable
if visible add
Intent gcm_rec = new Intent("your_action"); LocalBroadcastManager.getInstance(arg0).sendBroadcast(gcm_rec);
else
use Notification Manager for notification.
I think this is easy and best way to refresh your listview UI / call Fetching method.