As part of my learning Android Threading, I have done the below code.
package simple.learning.com.samplethread;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
MyThread myThread;
Button button;
private static class MyThread extends Thread {
public Handler mHandler;
public void run () {
Log.d ("TESTME", " iNSIDE RUN..");
Looper.prepare();
mHandler = new Handler () {
public void HandleMessage (Message msg) {
Log.d("TESTME", "iNSIDE HandleMessage");
if ( msg.what == 0) {
someWork();
}
}
};
Looper.loop();
}
public void someWork()
{
while (true) {
Log.d("TESTME", "Inside someWork ");
}
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myThread = new MyThread();
myThread.start();
Button btn = (Button) findViewById(R.id.button1);
assert btn != null;
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (myThread.mHandler != null) {
Log.d("TESTME", " bUTTON pRESSED..");
Message msg = myThread.mHandler.obtainMessage(0);
myThread.mHandler.sendMessage(msg);
}
}
});
}
}
When I Click the button, I expect the msg to be posted into the message queue. But, I don't see any output displayed. Any help would be appreciated.
You made a small mistake in overriding the handleMessage, instead of overriding the real one you added some method. Below is the working solution:
private static class MyThread extends Thread {
public Handler mHandler;
public void run() {
Log.d("TESTME", " iNSIDE RUN..");
Looper.prepare();
mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
Log.d("TESTME", "iNSIDE HandleMessage");
if (msg.what == 0) {
someWork();
}
}
};
Looper.loop();
}
public void someWork() {
while (true) {
Log.d("TESTME", "Inside someWork ");
}
}
}
Related
I am facing a problem, I have implemented a code, it is showing me message in Logs correctly but it doesn't update the TextView's text. Here i have tried this version. How i can update it? I tried it using threads as well but in vain.
I have seen many solution over this StackOverflow platform but i could not find my any solution for my problem.
package com.example.yousafmoh.seizuredetection;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.provider.ContactsContract;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.view.View;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import android.app.ProgressDialog;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.os.AsyncTask;
import java.io.IOException;
import java.io.InputStream;
import java.util.UUID;
public class ledControl extends AppCompatActivity {
// Button btnOn, btnOff, btnDis;
ImageButton On, Off, Discnt, Abt;
TextView txtMessage;
String address = null;
private ProgressDialog progress;
BluetoothAdapter myBluetooth = null;
BluetoothSocket btSocket = null;
private boolean isBtConnected = false;
//SPP UUID. Look for it
static final UUID myUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Intent newint = getIntent();
address = newint.getStringExtra(DeviceList.EXTRA_ADDRESS); //receive the address of the bluetooth device
//view of the ledControl
setContentView(R.layout.activity_led_control);
//call the widgets
On = (ImageButton)findViewById(R.id.on);
Off = (ImageButton)findViewById(R.id.off);
Discnt = (ImageButton)findViewById(R.id.discnt);
Abt = (ImageButton)findViewById(R.id.abt);
txtMessage = (TextView) findViewById(R.id.txtMessage);
new ConnectBT().execute(); //Call the class to connect
//myBluetoothThread();
//commands to be sent to bluetooth
On.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
turnOnLed(); //method to turn on
}
});
Off.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
turnOffLed(); //method to turn off
}
});
Discnt.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
Disconnect(); //close connection
}
});
}
private void myBluetoothThread() {
while(true)
{
if (btSocket!=null)
{
try
{
if(isBtConnected) {
InputStream inputStream = btSocket.getInputStream();
for (int i = 0; i <= inputStream.available(); i++) {
//Log.d("data", inputStream.read() + " "+"ok");
int val = inputStream.read();
if (val == 49) // seizure detected
{
this.runOnUiThread(new Runnable() {
#Override
public void run() {
txtMessage.setText("Seizure Detected!!!");
txtMessage.setTextColor(getResources().getColor(android.R.color.holo_red_dark));
Log.d("Message", " Detected");
}
});
Log.d("Message", " Detected");
} else if (val == 48) // no detection
{
this.runOnUiThread(new Runnable() {
#Override
public void run() {
txtMessage.setText("Normal Condition");
txtMessage.setTextColor(getResources().getColor(android.R.color.holo_blue_dark));
Log.d("Message", "not Detected");
}
});
Log.d("Message", "not Detected");
//, Toast.LENGTH_SHORT).show();
}
}
}
}
catch (IOException e)
{
msg("Error");
}
}
}
}
private void Disconnect()
{
if (btSocket!=null) //If the btSocket is busy
{
try
{
btSocket.close(); //close connection
}
catch (IOException e)
{ msg("Error");}
}
finish(); //return to the first layout
}
private void turnOffLed()
{
if (btSocket!=null)
{
try
{
InputStream inputStream = btSocket.getInputStream();
for(int i = 0 ; i <= inputStream.available();i++)
{
Log.d("data",inputStream.read()+" ");
}
Log.d("Bytes available off",String.valueOf(inputStream.available()));
Log.d("Message off",String.valueOf(inputStream.read()));
//btSocket.getOutputStream().write("0".toString().getBytes());
}
catch (IOException e)
{
msg("Error");
}
}
}
private void turnOnLed()
{
if (btSocket!=null)
{
try
{
InputStream inputStream = btSocket.getInputStream();
Log.d("Bytes available on",String.valueOf(inputStream.available()));
Log.d("Message on",String.valueOf(inputStream.read()));
Log.d("Message on",inputStream.toString());
btSocket.getOutputStream().write("1".toString().getBytes());
}
catch (IOException e)
{
msg("Error");
}
}
}
// fast way to call Toast
private void msg(String s)
{
Toast.makeText(getApplicationContext(),s,Toast.LENGTH_LONG).show();
}
public void about(View v)
{
if(v.getId() == R.id.abt)
{
Intent i = new Intent(this, AboutActivity.class);
startActivity(i);
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_led_control, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
private class ConnectBT extends AsyncTask<Void, Void, Void> // UI thread
{
private boolean ConnectSuccess = true; //if it's here, it's almost connected
#Override
protected void onPreExecute()
{
progress = ProgressDialog.show(ledControl.this, "Connecting...", "Please wait!!!"); //show a progress dialog
}
#Override
protected Void doInBackground(Void... devices) //while the progress dialog is shown, the connection is done in background
{
try
{
if (btSocket == null || !isBtConnected)
{
myBluetooth = BluetoothAdapter.getDefaultAdapter();//get the mobile bluetooth device
BluetoothDevice dispositivo = myBluetooth.getRemoteDevice(address);//connects to the device's address and checks if it's available
btSocket = dispositivo.createInsecureRfcommSocketToServiceRecord(myUUID);//create a RFCOMM (SPP) connection
BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
btSocket.connect();//start connection
progress.dismiss();
}
}
catch (IOException e)
{
ConnectSuccess = false;//if the try failed, you can check the exception here
}
return null;
}
#Override
protected void onPostExecute(Void result) //after the doInBackground, it checks if everything went fine
{
super.onPostExecute(result);
if (!ConnectSuccess)
{
msg("Connection Failed. Is it a SPP Bluetooth? Try again.");
finish();
}
else
{
msg("Connected.");
isBtConnected = true;
}
if(progress!=null)
progress.dismiss();
if(isBtConnected)
{
myBluetoothThread();
}
}
}
}
Try using this if its a fragment class
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
txtMessage.setText("Normal Condition");
txtMessage.setTextColor(getResources().getColor(android.R.color.holo_blue_dark));
}
});
and this is its an activity
this.runOnUiThread(new Runnable() {
#Override
public void run() {
txtMessage.setText("Normal Condition");
txtMessage.setTextColor(getResources().getColor(android.R.color.holo_blue_dark));
}
});
Another solution u can try is.
You can use handler
Handler handler = new Handler();
handler.post(new Runnable() {
public void run() {
txtMessage.setText("Seizure Detected!!!");
txtMessage.setTextColor(getResources().getColor(android.R.color.holo_red_dark));
}
});
I have read some article somewhere that you should not update your textview directly inside the Runnable Thread. So what I did is i created a function that updates the textview then the Runnable run method calls that function. So It look like this.
public class SampleActivity extends AppCompatActivity {
TextView sample;
int counter = 0;
Handler handler;
Runnable runnable;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sample);
sample = findViewById(R.id.sample);
handler = new Handler();
runnable = new Runnable() {
#Override
public void run() {
counter++;
updateTextView("Counter: " + counter);
handler.postDelayed(this, 1000);
}
};
handler.postDelayed(runnable, 1000);
}
public void updateTextView(String message) {
sample.setText(message);
}
But I tried it calling the sample.setText("Counter: "+counter) inside the Runnable Thread, it still works though.
Btw here is my sample.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/sample"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="SAWSAW"
android:textColor="#000"
android:textSize="32dp" />
</LinearLayout>
I'm trying to read an NDEF message from an NFC tag. The detection of the tag works correctly. For reading the NDEF data from the tag I'm running a TimerTask. The task polls the NDEF message from the tag with getNdefMessage() every 900 ms and updates the UI.
The procedure works perfect until I remove the phone. Than the app freezes without a logcat error message.
Does anyone have an idea why this happens?
package com.example.infcdemo;
import java.io.IOException;
import java.util.Timer;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.nfc.tech.NdefFormatable;
import android.nfc.tech.NfcA;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;
public class MainActivity extends Activity
{
protected NfcAdapter mAdapter;
protected PendingIntent mPendingIntent;
protected IntentFilter mIntentfilter;
protected String[][] mTechLists;
protected IntentFilter[] mFilters;
protected NfcA nfca = null;
protected Intent mIntent = null;
protected Tag mTag;
private boolean nfc_initialized = false;
Tag myTag = null;
Ndef _ndef = null;
Timer _incomingMessageTimer;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (nfc_initialized == false)
{
// Initialize NFC Specific
mAdapter = NfcAdapter.getDefaultAdapter(this);
mPendingIntent = PendingIntent.getActivity(this, 0,
new Intent(this, getClass())
.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 1);
IntentFilter ndef = new IntentFilter(
NfcAdapter.ACTION_TAG_DISCOVERED);
mTechLists = new String[][] { new String[] { NfcA.class.getName(), Ndef.class.getName(),
NdefFormatable.class.getName() } };
mFilters = new IntentFilter[] { ndef, };
nfc_initialized = true;
}
}
public void updateIncomingMessage(String msg)
{
TextView txtView = (TextView) findViewById(R.id.txtReceive);
txtView.setText(msg);
}
#Override
protected void onStart()
{
super.onStart();
_incomingMessageTimer = new Timer();
_incomingMessageTimer.schedule(new MessageReceiveTimer(new Handler(), this),0,900);
}
#Override
protected void onStop()
{
super.onStop();
_incomingMessageTimer.cancel();
_incomingMessageTimer.purge();
}
#Override
public void onNewIntent(Intent intent)
{
mIntent = intent;
String action = intent.getAction();
if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(action))
{
myTag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
if(_ndef != null)
{
try
{
_ndef.close();
_ndef = null;
}
catch (IOException e)
{
e.printStackTrace();
}
}
if(_ndef == null)
{
_ndef = Ndef.get(myTag);
try
{
_ndef.connect();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
}
#Override
public void onPause()
{
super.onPause();
mAdapter.disableForegroundDispatch(this);
}
#Override
public void onResume()
{
super.onResume();
mAdapter.enableForegroundDispatch(this, mPendingIntent, mFilters,
mTechLists);
}
}
//TimerTask Class
package com.example.infcdemo;
import java.util.TimerTask;
import android.nfc.NdefMessage;
import android.os.Handler;
public class MessageReceiveTimer extends TimerTask
{
Handler _handler;
MainActivity _mainActivity;
MessageReceiveTimer(Handler handler, MainActivity mainActivity)
{
super();
_handler = handler;
_mainActivity = mainActivity;
}
#Override
public void run()
{
_handler.post(new Runnable()
{
#Override
public void run()
{
try
{
if(_mainActivity._ndef != null)
{
NdefMessage ndefMsg = null;
if(_mainActivity._ndef.isConnected())
ndefMsg = _mainActivity._ndef.getNdefMessage();
else
ndefMsg = null;
byte[] ndefRecord = ndefMsg.getRecords()[0].getPayload();
String strMsg = new String(ndefRecord, "US-ASCII");
_mainActivity.updateIncomingMessage(strMsg);
}
}
catch (Exception e)
{
return;
}
}
});
}
}
The reason your app blocks when you remove a tag is that you execute IO operations on the tag in your app's main thread (UI thread).
You first create a timer that processes its scheduled tasks in a separate thread
_incomingMessageTimer = new Timer();
^^^^^^^^^^^
_incomingMessageTimer.schedule(new MessageReceiveTimer(new Handler(), this), 0, 900);
^^^^^^^^
However, when the TimerTask executes (on the Timer thread)
public class MessageReceiveTimer extends TimerTask {
#Override
public void run() {
// code excecution happens in the Timer thread
}
}
you immediately return control to the main (UI) thread by posting a Runnable on its message queue:
_handler.post(new Runnable() {
#Override
public void run() {
// code execution happens in the Handler's thread
}
});
The Handler's thread is the main (UI) thread in your case as you created the handler on the main thread:
_incomingMessageTimer.schedule(new MessageReceiveTimer(new Handler(), this),0,900);
^^^^^^^^^^^^^
Consequently the IO operation (_mainActivity._ndef.getNdefMessage()) will block the main thread. Note that the Android documentation explicitly says that this method "must not be called from the main application thread" (see here). The same applies to the connect() method, btw.
I am making a "Defend the castle" style android application. The game is complete, however I just need help closing my surfaceview and starting a new activity for when the the player has lost the game.
The condition for losing the game is just a boolean variable in my GameThread class. The variable is called "lost" and is by default set to false. When the life of the castle drops below 1, lost is set to true and a sound effect plays.
Ideally, I would like to stop the currently looping sound effects and open a new activity (which is already made and working) upon lost=true.
The main activity is as follows:
import android.app.Activity;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
public class MainActivity extends Activity {
Button btn_startGame;
Activity activity;
GameView mGameView;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
activity = this;
setContentView(R.layout.main);
btn_startGame = (Button) findViewById(R.id.btnStartGame);
btn_startGame.setOnClickListener(new OnClickListener() {
//#Override
public void onClick(View v) {
mGameView = new GameView(activity);
setContentView(mGameView);
mGameView.mThread.doStart();
}
});
}
#Override
public boolean onTouchEvent(MotionEvent event) {
try {
mGameView.mThread.onTouch(event);
} catch(Exception e) {}
return true;
}
#Override
public void onConfigurationChanged(Configuration newConfig) {
// ignore orientation/keyboard change
super.onConfigurationChanged(newConfig);
}
}
The surfaceview is created in this class called GameView:
import android.content.Context;
import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;
public class GameView extends SurfaceView implements Callback {
Context mContext;
GameThread mThread;
public GameView(Context context) {
super(context);
this.mContext = context;
getHolder().addCallback(this);
mThread = new GameThread(getHolder(), mContext, new Handler() {
#Override
public void handleMessage(Message m) {
// Use for pushing back messages.
}
});
setFocusable(true);
}
//#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
Log.d(this.getClass().toString(), "in SurfaceChanged()");
}
//#Override
public void surfaceCreated(SurfaceHolder holder) {
Log.d(this.getClass().toString(), "in SurfaceCreated()");
mThread.running = true;
mThread.start();
}
//#Override
public void surfaceDestroyed(SurfaceHolder holder) {
Log.d(this.getClass().toString(), "in SurfaceDestroyed()");
boolean retry = true;
mThread.running = false;
while (retry) {
try {
mThread.join();
retry = false;
} catch (InterruptedException e) {
}
GameThread.music.stop();
GameThread.groan1.stop();
GameThread.groan2.stop();
GameThread.walk.stop();
GameThread.music.release();
GameThread.groan1.release();
GameThread.groan2.release();
GameThread.walk.release();
GameThread.shoot.release();
}
}
}
The GameThread class contains all of the drawing, the logic and all a run method (below).
#Override
public void run() {
// check if condition here
if(lost){
mContext.runOnUiThread(new Runnable() {
#Override
public void run() {
//start Activity here
Intent intent = new Intent(mContext, LoseActivity.class);
mContext.startActivity(intent);
}
});
}
else{
if (running == true) {
while (running) {
Canvas c = null;
try {
c = mHolder.lockCanvas();
if (width == 0) {
width = c.getWidth();
height = c.getHeight();
player.x = 50;
player.y = 45;
}
synchronized (mHolder) {
long now = System.currentTimeMillis();
update();
draw(c);
ifps++;
if (now > (mLastTime + 1000)) {
mLastTime = now;
fps = ifps;
ifps = 0;
}
}
} finally {
if (c != null) {
mHolder.unlockCanvasAndPost(c);
}
}
}
}
}
The activity that I want to start is called LoseActivity.class. Thank you in advance for any and all help. If anybody needs any further code/explanations, I will be more than happy to post it.
Use runOnUiThread for starting Activity from Thread as:
Change your main Activity as:
public class MainActivity extends Activity {
Button btn_startGame;
Activity activity;
GameView mGameView;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
activity = this;
setContentView(R.layout.main);
btn_startGame = (Button) findViewById(R.id.btnStartGame);
btn_startGame.setOnClickListener(new OnClickListener() {
//#Override
public void onClick(View v) {
mGameView = new GameView(activity,MainActivity.this);
setContentView(mGameView);
mGameView.mThread.doStart();
}
});
}
///your code.....
Change your GameView class as:
public class GameView extends SurfaceView implements Callback {
Context mContext;
Activity contextx;
GameThread mThread;
public GameView(Context context,Activity contextx) {
super(context);
this.mContext = context;
this.contextx=contextx;
getHolder().addCallback(this);
mThread = new GameThread(getHolder(), mContext, new Handler() {
#Override
public void handleMessage(Message m) {
// Use for pushing back messages.
}
});
setFocusable(true);
}
//your code here..........
#Override
public void run() {
// check if condition here
if(lost){
contextx.runOnUiThread(new Runnable() {
#Override
public void run() {
//start Activity here
Intent intent = new Intent(contextx, LoseActivity.class);
contextx.startActivity(intent);
}
});
}
else{
//your code here.........
I have this code:
package org.example.Threading;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class ThreadingActivity extends Activity implements OnClickListener {
/** Called when the activity is first created. */
private doinback background = new doinback();
Handler handle= new Handler(){
#Override
public void handleMessage(Message msg) {
Log.e("INSIDE HANDLER", "About to stop the thread.");
background.stopThread();
}};
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Log.e("ONCREATE", "BEFORE Thread");
background.start();
Log.e("ONCREATE", "AFTER Thread started");
View button = (Button)findViewById(R.id.button1);
button.setOnClickListener(this);
}
class doinback extends Thread{
private volatile boolean isRunning = false;
public void run() {
while(isRunning){
Log.e("INSIDE THREAD", "about to sleep");
handle.sendMessage(handle.obtainMessage());
}
}
public void stopThread()
{
isRunning = false;
}
public void startThread(){
Log.e("INSIDE StartThread","MAKING isRunning True");
isRunning = true;
}
}
public void onClick(View v) {
background.startThread();
Log.e("INSIDE ONCLICK", "made isRunning true, about to leave");
}
}
I am trying to understand why it does not go back to the thread and if there is something I am doing wrong and if so what is the best way to go back and forth from a thread, for instance with the stopThread() function I change the value of the while variable to stop the thread from running. When I run the code and press the button it does not start the thread. Any ideas why?
When background.start() is called, isRunning is still false, so the thread is started(but didn't enter the while loop) and stopped immediately.
To ensure the thread to enter the while loop when startThread is called, you can put the following code in the startThread() method:
public void startThread(){
isRunning = true;
start();
}
And you don't call background.start() in onCreate(), just remove that line.
EDIT
If you want to keep a single thread alive, so you can "start" it and "stop" it as many times as you like, you can use the following code:
public void run () {
while (isRunning) {
if(!isWorking) {
try { Thread.sleep(10); } catch (InterruptedException ex) { }
continue;
}
//.. do your work here.
}
}
You control the running state of the thread with isRunning, and the working state with isWorking.
I want to display toast message inside timer and I used the following code :
timer.scheduleAtFixedRate( new TimerTask()
{
public void run()
{
try {
fun1();
} catch (Exception e) {e.printStackTrace(); }
}
}, 0,60000);
public void fun1()
{
//want to display toast
}
And I am getting following error:
WARN/System.err(593): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
WARN/System.err(593): at android.os.Handler.(Handler.java:121)
WARN/System.err(593): at android.widget.Toast.(Toast.java:68)
WARN/System.err(593): at android.widget.Toast.makeText(Toast.java:231)
Thanks.
You can't make UI updates inside separate Thread, like Timer. You should use Handler object for UI update:
timer.scheduleAtFixedRate( new TimerTask() {
private Handler updateUI = new Handler(){
#Override
public void dispatchMessage(Message msg) {
super.dispatchMessage(msg);
fun1();
}
};
public void run() {
try {
updateUI.sendEmptyMessage(0);
} catch (Exception e) {e.printStackTrace(); }
}
}, 0,60000);
The easiest way (IMO) is:
new Timer().scheduleAtFixedRate(new TimerTask() {
#Override
public void run() {
final String message = "Hi";
MyActivity.this.runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(MyActivity.this, message, Toast.LENGTH_SHORT).show();
}
});
}
});
The key being MyActivity.this.runOnUiThread(Runnable).
create a Handler and display toast in this
private Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
// Toast here
}
};
You need access to the Context of the application to be able to do this. Try creating your own class which takes the context as input parameter:
private class MyTimerTask extends TimerTask {
private Context context;
public MyTimerTask(Context context) {
this.context = context;
}
#Override
public void run() {
Toast.makeText(context, "Toast text", Toast.LENGTH_SHORT).show();
}
}
Then in your timer:
timer.scheduleAtFixedRate( new MyTimerTask(this), 0,60000);
I wanted to make a simple project that could display a Toast in a Timer.
The Timer would be started using a service. Then, the Timer starts when the service is started and stops when service is stopped.
Class 1
package com.example.connect;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity {
Button button1,button2;
private Handler mHandler = new Handler();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button1=(Button)findViewById(R.id.button1);
button2=(Button)findViewById(R.id.button2);
}
public void Start(View v)
{
startService(new Intent(MainActivity.this , Connect_service.class));
}
public void Stop(View v)
{
stopService(new Intent(MainActivity.this , Connect_service.class));
}
}
Class 2
package com.example.connect;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.widget.Toast;
public class Connect_service extends Service{
Timer timer = new Timer();
TimerTask updateProfile = new CustomTimerTask(Connect_service.this);
public void onCreate() {
super.onCreate();
Toast.makeText(this, "Service Started", Toast.LENGTH_SHORT).show();
timer.scheduleAtFixedRate(updateProfile, 0, 5000);
}
#Override
public void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
Toast.makeText(this, "Service Stopped", Toast.LENGTH_SHORT).show();
timer.cancel();
}
#Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
return null;
}
}
Class 3
package com.example.connect;
import java.util.TimerTask;
import android.content.Context;
import android.os.Handler;
import android.widget.Toast;
public class CustomTimerTask extends TimerTask {
private Context context;
private Handler mHandler = new Handler();
public CustomTimerTask(Context con) {
this.context = con;
}
#Override
public void run() {
new Thread(new Runnable() {
public void run() {
mHandler.post(new Runnable() {
public void run() {
Toast.makeText(context, "In Timer", Toast.LENGTH_SHORT).show();
}
});
}
}).start();
}
}
I'm trying to make my own toast with my own views.
I've successfully combined your approaches. The following code allows me to show toasts and change/remove views without crashing, just change the parameters of the MyTimerTask constructor to whatever you need to work on.
public void yourFunction(){
Timer timer = new Timer();
MyTimerTask mtc = new MyTimerTask(this.getContext(), tvNotice);
timer.schedule(mtc, 1000);
}
private class MyTimerTask extends TimerTask {
private TextView tv;
private Context context;
public MyTimerTask(Context pContext, TextView pTv) {
this.tv = pTv;
this.context = pContext;
}
#Override
public void run() {
updateUI.sendEmptyMessage(0);
}
private Handler updateUI = new Handler(){
#Override
public void dispatchMessage(Message msg) {
super.dispatchMessage(msg);
tv.setText("TextView Message");
Toast.makeText(context, "Toast Message", 0).show();
}
};
}
You have to call UIThread for showing Toast, not from timer thread.
Else call UI thread from that timer thread.
This link will help you,
http://developer.android.com/resources/articles/timed-ui-updates.html
and this
http://developer.android.com/guide/appendix/faq/commontasks.html#threading