Develop Reference

Android Toast doesn't show

I have an application that get user input(name and number) , then scanning QR code , and on a press of a button it send the data to my server and get replay from it.
everything is working now as it should.(I can see the message for the server as string when I'm in debug mode).
but I can't see the toast - it doesn't shown
why?
this is the class I have in the ScanActivity.java
public class ScannedBarcodeActivity extends AppCompatActivity {
SurfaceView surfaceView;
TextView txtBarcodeValue;
private BarcodeDetector barcodeDetector;
private CameraSource cameraSource;
private static final int REQUEST_CAMERA_PERMISSION = 201;
Button btnAction;
String intentData = "";
String ServerReply;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scan_barcode);
initViews();
}
private void initViews() {
txtBarcodeValue = findViewById(R.id.txtBarcodeValue);
surfaceView = findViewById(R.id.surfaceView);
btnAction = findViewById(R.id.btnAction);
btnAction.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (intentData.length() > 0) {
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
try {
String server_ip = "My.Server.Public.IP";
int server_port = 9999;
String messageStr = intentData + "!" + phone +"!"+ name+"!##";
Socket clientSocket = new Socket(server_ip, server_port);
PrintWriter mBufferOut = new PrintWriter((new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()))), true);
BufferedReader mBufferIn = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
mBufferOut.println(messageStr);
ServerReply = mBufferIn.readLine();
mBufferIn.close();
//see why this is not working - can;t see the toast
Toast.makeText(getApplicationContext(),"inside the thread",Toast.LENGTH_LONG).show();
clientSocket.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
});
// Toast.makeText(getApplicationContext(),ServerReply,Toast.LENGTH_LONG).show();
thread.start();
}
Toast.makeText(getApplicationContext(),ServerReply,Toast.LENGTH_LONG).show();
SystemClock.sleep(1000); //ms
Toast.makeText(getApplicationContext(),"Going to Main Page now",Toast.LENGTH_LONG).show();
finish();
}
// }
});
}
this is the how it's look after what you told me to do :(still doesn't work , and for some reason it "skip" the toast part)
public class ScannedBarcodeActivity extends AppCompatActivity {
SurfaceView surfaceView;
TextView txtBarcodeValue;
private BarcodeDetector barcodeDetector;
private CameraSource cameraSource;
private static final int REQUEST_CAMERA_PERMISSION = 201;
Button btnAction;
String intentData = "";
boolean isEmail = false;
String ServerReply;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scan_barcode);
initViews();
}
private void initViews() {
txtBarcodeValue = findViewById(R.id.txtBarcodeValue);
surfaceView = findViewById(R.id.surfaceView);
btnAction = findViewById(R.id.btnAction);
;
btnAction.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (intentData.length() > 0) {
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
try {
String server_ip = "My.Server.IP";
int server_port = 9999;
String messageStr = intentData + "!" + phone +"!"+ name+"!##";
Socket clientSocket = new Socket(server_ip, server_port);
PrintWriter mBufferOut = new PrintWriter((new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()))), true);
BufferedReader mBufferIn = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
mBufferOut.println(messageStr);
ServerReply = mBufferIn.readLine();
mBufferIn.close();
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(getApplicationContext(),"inside the thread",Toast.LENGTH_SHORT).show();
}
});
clientSocket.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
});
thread.start();
}
SystemClock.sleep(1000); //ms
finish();
}
// }
});
}

All the UI rendering should be done on main thread, you can use view handler to do that
v.post(new Runnable(){
Toast.makeText(getApplicationContext(),"inside the thread",Toast.LENGTH_LONG).show();
});

This will execute on UI thread
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(getApplicationContext(),"inside the thread",Toast.LENGTH_SHORT).show();
}
});

Your toast is coming from a background thread, it needs to be executed on the main/UI thread
Handler handler = new Handler(Looper.getMainLooper());
handler.post(new Runnable() {
#Override
public void run() {
Toast.makeText(getApplicationContext(),"inside the thread",Toast.LENGTH_LONG).show();
}
});

1) You have to write toast in UI thread. like blow
// you can write toast in UI thread like this
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(getApplicationContext(),"inside the thread",Toast.LENGTH_LONG).show();
}
});
2) You have to make sure intentData.length() is not 0 ( if your intentData is empty then your thread will never execute, be sure about that.)
if (intentData.length() > 0) {...}
3) And also make sure your code not given any exception before showing your toast message [handle your exception in catch block like following]
catch (Exception e){
Log.e("Exception","your exception is "+e.toString());
}
Hope it helps you.

Toast can't be run on other than the UI thread, you can use
runOnUiThread(new Runnable() {
#Override
public void run() {
//see why this is not working - can;t see the toast
Toast.makeText(getApplicationContext(),"inside the thread",Toast.LENGTH_LONG).show();
}
});

RealTime Graph Entry

Please understand that I am using Google Translator because I do not understand English well.
I am currently working on an application that draws an EMG sensor value sent by Arduino via Bluetooth communication and a smartphone draws a graph based on that value.
Currently the application configuration has one activity and one fragment.
The Bluetooth function is in the activity and the graph is in the fragment.
I want to have the graph drawn only when the value comes in via Bluetooth communication. What should I do?
The code now depends on the fact that the fragment receives a value, even though the fragment is requesting a value.
Fragment
private void feedMultiple() {
if (thread != null)
thread.interrupt();
final Runnable runnable = new Runnable() {
#Override
public void run() {
addEntry();
}
};
thread = new Thread(new Runnable() {
#Override
public void run() {
while (loop) {
// Don't generate garbage runnables inside the loop
getActivity().runOnUiThread(runnable);
try {
Thread.sleep(5);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
break;
}
}
}
});
thread.start();
}
Activity
void beginListenForData() {
final Handler handler = new Handler();
readBufferPosition = 0;
readBuffer = new byte[1024];
mWorkerThread = new Thread(new Runnable()
{
#Override
public void run() {
while(!Thread.currentThread().isInterrupted()) {
try {
int byteAvailable = mInputStream.available();
if(byteAvailable > 0) {
byte[] packetBytes = new byte[byteAvailable];
mInputStream.read(packetBytes);
for(int i=0; i<byteAvailable; i++) {
byte b = packetBytes[i];
if(b == mCharDelimiter) {
byte[] encodedBytes = new byte[readBufferPosition];
System.arraycopy(readBuffer, 0, encodedBytes, 0, encodedBytes.length);
final String data = new String(encodedBytes,"UTF-8");
readBufferPosition = 0;
handler.post(new Runnable(){
#Override
public void run() {
//raw = data.split("#");
bundle.putString("yValue1", data);
}
});
}
else {
readBuffer[readBufferPosition++] = b;
}
}
}
} catch (Exception e) {
Toast.makeText(getApplicationContext(), "데이터 수신 중 오류가 발생 했습니다.", Toast.LENGTH_LONG).show();
finish();
}
}
}
});
mWorkerThread.start();
}

Using handler to change ui, still "only the original thread that created a view hierarchy can touch its views." error

I have two threads, two handlers. From thread i check a random number and send result to handle to update ui. But i am getting the error "only the original thread that created a view hierarchy can touch its views.". I searched some articles, they tell to use handler. I am doing that, yet can not avoid the errors.
After some checking, I found that it crashes when A sends the result. In case of B, it works
Also, can i use one handler for two thread?
public class MainActivity extends Activity implements View.OnClickListener{
Button start;
TextView status_B, status_A;
Boolean isRunning;
Thread Athread, Bthread;
int a, b;
Handler a_Handler, b_Handler;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Initialize variables
start = (Button) findViewById(R.id.button);
start.setOnClickListener(this);
status_B = (TextView) findViewById(R.id.textView);
status_A = (TextView) findViewById(R.id.textView1);
a_Handler = new Handler() {
public void handleMessage(Message msg)
{
int number = msg.getData().getInt("number");
String winner = msg.getData().getString("winner");
start.setEnabled(true);
isRunning = false;
status_A.setText(winner + number);
}
};
b_Handler = new Handler() {
public void handleMessage(Message msg)
{
int number = msg.getData().getInt("number");
String winner = msg.getData().getString("winner");
start.setEnabled(true);
isRunning = false;
status_B.setText(winner + number);
}
};
}
#Override
protected void onStart() {
super.onStart();
isRunning = false;
}
#Override
public void onClick(View v) {
start.setEnabled(false);
status_B.setText("Guessing...");
if (!isRunning)
{
Athread = new Thread(new Runnable() {
#Override
public void run() {
while (isRunning)
{
try
{
Athread.sleep(1000);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
a = (int) (Math.random()*1000);
System.out.println("a "+ a);
if(a%7 == 0) {
isRunning = false;
Bundle bundle = new Bundle();
bundle.putString("winner", "A");
bundle.putInt("number", a);
Message msg = a_Handler.obtainMessage();
msg.setData(bundle);
a_Handler.handleMessage(msg);
}
}
}
});
Bthread = new Thread(new Runnable() {
#Override
public void run() {
while(isRunning)
{
try
{
Bthread.sleep(1000);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
b = (int) (Math.random()*1000);
System.out.println("b "+ b);
if(b%7 == 0) {
isRunning = false;
Bundle bundle = new Bundle();
bundle.putString("winner", "B");
bundle.putInt("number", b);
Message msg = b_Handler.obtainMessage();
msg.setData(bundle);
b_Handler.sendMessage(msg);
}
}
}
});
isRunning = true;
Athread.start();
Bthread.start();
}
}
}

You need put your code to modify views on UI thread:
a_Handler = new Handler() {
public void handleMessage(Message msg)
{
final int number = msg.getData().getInt("number");
final String winner = msg.getData().getString("winner");
runOnUiThread(new Runnable() {
#Override
public void run() {
start.setEnabled(true);
status_A.setText(winner + number);
}
});
isRunning = false;
}
};
b_Handler = new Handler() {
public void handleMessage(Message msg)
{
final int number = msg.getData().getInt("number");
final String winner = msg.getData().getString("winner");
runOnUiThread(new Runnable() {
#Override
public void run() {
start.setEnabled(true);
status_B.setText(winner + number);
}
});
isRunning = false;
}
};

Stop moving ball on Button click

I have a ball that keeps moving from start. I want to stop ball on button click. When I clicked on button it show the Toast, but the ball keep on moving. It doesn't stop.
Please guide me how to stop ball on button click. My code for Activity is there.
#SuppressLint("HandlerLeak")
public class BounceActivity extends Activity {
private static final int GAME_START = 500;
private static final int GAME_STOP = 600;
Thread myRefreshThread = null;
BounceView myBounceView = null;
int width = 0;
int height = 0;
Handler myGUIUpdateHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case BounceActivity.GAME_START:
myBounceView.invalidate();
break;
case BounceActivity.GAME_STOP:
Log.d("BounceView", "Game state: " + BounceView.game_state);
Toast.makeText(BounceActivity.this, "Game stopped", Toast.LENGTH_SHORT).show();
myRefreshThread = null;
break;
}
super.handleMessage(msg);
}
};
#Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
this.myBounceView = new BounceView(this, dm.widthPixels, dm.heightPixels);
this.setContentView(myBounceView);
myRefreshThread = new Thread(new RefreshRunner());
myRefreshThread.start();
}
class RefreshRunner implements Runnable {
#Override
public void run() {
while (myRefreshThread != null) {
if(BounceView.game_state == 0) {
Message msg = Message.obtain();
msg.what = BounceActivity.GAME_START;
myGUIUpdateHandler.sendMessage(msg);
} else if (BounceView.game_state == 1) {
Message msg = Message.obtain();
msg.what = BounceActivity.GAME_STOP;
myGUIUpdateHandler.sendMessage(msg);
}
try {
Thread.sleep(100);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
}}

You are accessing and setting myRefreshThread on different threads, which can be problematic.
Instead of checking if myRefreshThread is null in your while loop, you can add a "running" flag to RefreshRunner, and a stop method that sets it to false.
Than check that flag in the while loop.
Hold a reference to your RefreshRunner (the one you pass to myRefreshThread), and call stop() when you want the animation to stop.
class RefreshRunner implements Runnable {
private void mRunning = true;
public void stop () {
mRunning = false;
}
#Override
public void run() {
while (mRunning) {
if(BounceView.game_state == 0) {
Message msg = Message.obtain();
msg.what = BounceActivity.GAME_START;
myGUIUpdateHandler.sendMessage(msg);
} else if (BounceView.game_state == 1) {
Message msg = Message.obtain();
msg.what = BounceActivity.GAME_STOP;
myGUIUpdateHandler.sendMessage(msg);
}
try {
Thread.sleep(100);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
}}

android multithreading: thread.join() does not work as expected

I have trouble using thread.join in my code below. It should wait for the thread to finish before executing the codes after it, right? It was behaving differently on different occasions.
I have three cases to check if my code goes well
App is used for the first time - works as expected but the loading page don't appear while downloading
App is used the second time (db is up to date) - works okay
App is used the third time (db is outdated, must update) - won't update, screen blacks out, then crashes
I think I have problems with this code on onCreate method:
dropOldSchedule();
dropThread.join();
triggerDownload();
Based on the logs, the code works until before this part... What can be the problem?
MainActivity.java
public class MainActivity extends Activity {
final static int INDEX_ACCTTYPE = 0;
final static int INDEX_ECN = 1;
final static int INDEX_TLN = 2;
final static int INDEX_SIN = 3;
final static int INDEX_MOBILE = 4;
final static int INDEX_CITY = 5;
final static int INDEX_START_DATE = 6;
final static int INDEX_START_TIME = 7;
final static int INDEX_END_DATE = 8;
final static int INDEX_END_TIME = 9;
final static int INDEX_REASON = 10;
final static int INDEX_DETAILS = 11;
DatabaseHandler db;
String str;
ProgressDialog pd;
TextView homeText1, homeText2, homeText3, homeText4;
final private String csvFile = "http://www.meralco.com.ph/pdf/pms/pms_test.csv";
final private String uploadDateFile = "http://www.meralco.com.ph/pdf/pms/UploadDate_test.txt";
Thread dropThread = new Thread(new Runnable() {
public void run() {
db = new DatabaseHandler(MainActivity.this);
db.dropOldSchedule();
runOnUiThread(new Runnable() {
public void run() {
while (!pd.isShowing());
db.close();
pd.dismiss();
}
});
}
});
Thread getUploadDateThread = new Thread(new Runnable() {
public void run() {
try {
URL myURL = new URL(uploadDateFile);
BufferedReader so = new BufferedReader(new InputStreamReader(myURL.openStream()));
while (true) {
String output = so.readLine();
if (output != null) {
str = output;
}
else {
break;
}
}
so.close();
}
catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
runOnUiThread(new Runnable() {
public void run() {
while (!pd.isShowing());
pd.dismiss();
}
});
}
});
Thread downloadThread = new Thread(new Runnable() {
public void run() {
db = new DatabaseHandler(MainActivity.this);
db.beginTransaction();
try {
URL url = new URL(csvFile);
Log.i("dl", "start");
InputStream input = url.openStream();
CSVReader reader = new CSVReader(new InputStreamReader(input));
Log.i("dl", "after reading");
String [] sched;
while ((sched = reader.readNext()) != null) {
if(sched[INDEX_CITY].equals("")) sched[INDEX_CITY]="OTHERS";
try {
db.addRow(sched[INDEX_SIN], sched[INDEX_CITY],
sched[INDEX_START_DATE], sched[INDEX_START_TIME],
sched[INDEX_END_DATE], sched[INDEX_END_TIME],
sched[INDEX_DETAILS], sched[INDEX_REASON]);
} catch (IndexOutOfBoundsException e) {
db.addRow(sched[INDEX_SIN], sched[INDEX_CITY],
sched[INDEX_START_DATE], sched[INDEX_START_TIME],
sched[INDEX_END_DATE], sched[INDEX_END_TIME],
"", sched[INDEX_REASON]);
//e.printStackTrace();
}
}
input.close();
Log.i("dl", "finished");
} catch (MalformedURLException e) {
e.printStackTrace();
db.endTransaction();
} catch (IOException e) {
e.printStackTrace();
db.endTransaction();
}
Log.d("Count", ""+db.count());
db.setTransactionSuccessful();
db.endTransaction();
writeUploadDateInTextFile();
}
});
#SuppressWarnings("unqualified-field-access")
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.pms_main);
Button home = (Button) findViewById(R.id.home);
home.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, MeralcoSuite_TabletActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
finish();
}
});
homeText1 = (TextView) findViewById(R.id.home_text1);
homeText2 = (TextView) findViewById(R.id.home_text2);
homeText3 = (TextView) findViewById(R.id.home_text3);
homeText4 = (TextView) findViewById(R.id.home_text4);
homeText1.setVisibility(View.INVISIBLE);
homeText2.setVisibility(View.INVISIBLE);
homeText3.setVisibility(View.INVISIBLE);
homeText4.setVisibility(View.INVISIBLE);
getUploadDate();
try {
getUploadDateThread.join(); //wait for upload date
Log.d("getUploadDate","thread died, upload date=" + str);
if(dbExists()){
db = new DatabaseHandler(MainActivity.this);
Log.d("Count", "" + db.count());
db.close();
if(!uploadDateEqualsDateInFile()){
dropOldSchedule();
dropThread.join();
triggerDownload();
}
showDisclaimer();
Log.i("oncreate", "finished!");
return;
}
triggerDownload();
showDisclaimer();
Log.i("oncreate", "finished!");
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void dropOldSchedule(){
if(pd!=null && pd.isShowing())
pd.setTitle("Getting upload date...");
else
pd = ProgressDialog.show(this, "Getting upload date",
"This may take a few minutes...", true, false);
dropThread.start();
}
public void triggerDownload() {
if (!checkInternet()) {
showAlert("An internet connection is required to perform an update, please check that you are connected to the internet");
return;
}
if(pd!=null && pd.isShowing())
pd.setTitle("Getting upload date...");
else
pd = ProgressDialog.show(this, "Getting upload date",
"This may take a few minutes...", true, false);
downloadThread.start();
}
public void getUploadDate() {
Log.d("getUploadDate", "getting upload date of schedule");
if(pd!=null && pd.isShowing())
pd.setTitle("Getting upload date...");
else
pd = ProgressDialog.show(this, "Getting upload date",
"This may take a few minutes...", true, false);
getUploadDateThread.start();
}
public void writeUploadDateInTextFile() {
Log.d("writeUploadDateTextFile", "writing:"+str);
try {
OutputStreamWriter out = new OutputStreamWriter(openFileOutput(
"update.txt", 0));
out.write(str);
out.close();
} catch (java.io.IOException e) {
e.printStackTrace();
}
}
public void showDisclaimer() {
Log.d("ShowDisclaimer", "showing disclaimer");
homeText3
.setText("..." + str
+ "...");
homeText1.setVisibility(View.VISIBLE);
homeText2.setVisibility(View.VISIBLE);
homeText3.setVisibility(View.VISIBLE);
homeText4.setVisibility(View.VISIBLE);
Log.d("showDisclaimer", "finished showing disclaimer");
}
public boolean uploadDateEqualsDateInFile() {
Log.d("uploadDateEqualsDateInFile","comparing schedule upload dates");
try {
String recordedDate = "";
InputStream instream = openFileInput("update.txt");
if (instream != null) { // if file the available for reading
Log.d("uploadDateEqualsDateInFile","update.txt found!");
InputStreamReader inputreader = new InputStreamReader(instream);
BufferedReader buffreader = new BufferedReader(inputreader);
String line = null;
while ((line = buffreader.readLine()) != null) {
recordedDate = line;
Log.d("uploadDateEqualsDateInFile","recorded:"+recordedDate);
}
Log.d("uploadDateEqualsDateInFile","last upload date: " + str + ", recorded:" +recordedDate);
if(str.equals(recordedDate)) return true;
return false;
}
Log.d("uploadDateEqualsDateInFile","update.txt is null!");
return false;
} catch (FileNotFoundException e) {
e.printStackTrace();
return false;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
public boolean checkInternet() {
ConnectivityManager cm = (ConnectivityManager) this
.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo infos[] = cm.getAllNetworkInfo();
for (NetworkInfo info : infos)
if (info.getState() == NetworkInfo.State.CONNECTED
|| info.getState() == NetworkInfo.State.CONNECTING) {
return true;
}
return false;
}
public boolean dbExists() {
File database=getApplicationContext().getDatabasePath(DatabaseHandler.DATABASE_NAME);
if (!database.exists()) {
Log.i("Database", "Not Found");
return false;
}
Log.i("Database", "Found");
return true;
}
#Override
protected void onDestroy() {
super.onDestroy();
if (db != null) {
db.close();
}
}
#Override
protected void onPause() {
super.onPause();
if (db != null) {
db.close();
}
}
}

Sorry but I couldn't find mistakes or problems in your code. But I would strongly recommend you to use AsyncTask for doing something in different thread. AsyncTask is very easy to use and I would say that it is one of the biggest advantages of java. I really miss it in obj-c.
http://labs.makemachine.net/2010/05/android-asynctask-example/
http://marakana.com/s/video_tutorial_android_application_development_asynctask_preferences_and_options_menu,257/index.html
check those links hope that will help you.

It was already mentioned that AsyncTask is the better alternative. However, it may be the case, that your call to join will throw InterruptedException. Try to use it like this:
while(getUploadDateThread.isRunning()){
try{
getUploadDateThread.join();
} catch (InterruptedException ie){}
}
// code after join

I think the problem that your facing is that you are blocking the UI thread when you call join in the onCreate() method. You should move this code into another thread which should execute in the background and once its done you can update the UI.
Here is a sample code:
final Thread t1 = new Thread();
final Thread t2 = new Thread();
t1.start();
t2.start();
new Thread(new Runnable() {
#Override
public void run() {
// Perform all your thread joins here.
try {
t1.join();
t2.join();
} catch (Exception e) {
// TODO: handle exception
}
// This thread wont move forward unless all your threads
// mentioned above are executed or timed out.
// ------ Update UI using this method
runOnUiThread(new Runnable() {
#Override
public void run() {
// Update UI code goes here
}
});
}
}).start();