I am trying to do this simple task. I have two buttons called START and STOP, I want to execute some task in loop by clicking on START and want to exit from this loop by clicking STOP.
Code-
public class DrawPath extends Activity implements View.OnClickListener {
ArrayList<LatLng> positions = new ArrayList<LatLng>() ;
static int c=1;
Location location;
GoogleMap mMap;
Button btStart,btStop;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.drawpath);
initializeVar();
btStart.setOnClickListener(this);
btStop.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
c = 0;
System.out.println("tested2");
}
});
}
private void initializeVar()
{
btStart=(Button)findViewById(R.id.btStart);
btStop=(Button)findViewById(R.id.btStop);
}
#Override
public void onClick(View v) {
getupdate(1);
}
private void getupdate(int d) {
c = d;
CurrentPosition currentPosition = new CurrentPosition(this);
if (c == 0) {
System.out.println("Done");
} else {
location = currentPosition.getCurrentLocation();
LatLng pos = new LatLng(location.getLatitude(), location.getLongitude());
positions.add(pos);
System.out.println("running");
try {
Thread.sleep(5000);
getupdate(c);
} catch (Exception e) {
}
}
}
}
Somebody please share any idea how to achieve it.
You can use Handler with Runnable to stop your thread after STOP button click.
I am giving you hint use following code according to your requirement
Handler handler = new Handler();
Runnable runable = new Runnable({
#Override
public void run(){
// count
handler.postDelayed(this, 1000);
}
});
Now you can call following line from your btnStop.onClick().
handler.removeCallbacks(runable);
Check this for more details on Handler and Runnable
What I suggest it create a inner class which extends Thread and according to user's action start and stop the thread. here is an example
class DrawPath extends Activity implements View.OnClickListener {
MyThread thread;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.drawpath);
initializeVar(); //not in my code so you add it
btStart.setOnClickListener(this);
btStop.setOnClickListener(this);
}
#Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.btStart:
if (thread == null) {
thread = new MyThread();
thread.start();
}
break;
case R.id.btStop:
if (thread != null) {
thread.interrupt();
}
break;
}
}
class MyThread extends Thread {
#Override
public void run() {
while (true) {
try {
Thread.sleep(3000);
//your stuff goes here or before sleep
} catch (InterruptedException e) {
e.printStackTrace();
thread = null;
break;
}
}
}
}
//whey interrupt here bcz infinite loop will be running until and unless you stop it.
#Override
protected void onDestroy() {
super.onDestroy();
if (thread != null)
thread.interrupt();
}
}
I saw your code which needs little more improvements that's why I wrote this big file :)
Suggestions :
Checkout the implementation of onClickListener.
Stopping thread at onDestroy() because thread will be running even after you close your application, so you need to stop when you
come out (destroyed) of your main activity.
Related
I am trying to play with progress bars. I have this (below) simple activity which runs a progress bar N times one after the other, when I call Progress(N). It is working great but the problem I am facing is, if I press back button. I get into the mainActivity but the progress bars (the threads) are still running in background one after the other. As soon as they finish N loops, the intent is called and whatever I would be doing would be interrupted by this LOOP_OVER activity.
I tried solving this by my own. I tried using variable of Thread class (before I was directly doing it). And tried to interrupt() it at onDestroy() or even just before the intent is called but its not helping. How should I go about it?
public class Loop extends Activity {
private ProgressBar progressBar;
private CircleProgress circleProgress;
private int progressStatus = 0;
private Handler handler = new Handler();
private TextView myView;
private int started = 0, doneLoop=0;
private Thread th;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_loop);
progressBar = (ProgressBar) findViewById(R.id.progressBar1);
circleProgress = (CircleProgress) findViewById(R.id.circle_progress);
myView = (TextView) findViewById(R.id.instruction);
progressBar.setScaleY(3f);
// Start long running operation in a background thread
Progress(3);
}
#Override
public void onDestroy() {
// Below, everything I am just
th.interrupt();
Loop.this.finish();
Thread.currentThread().interrupt();
super.onDestroy();
}
public void Progress(final int numberOfRuns){
// QueView.setText(Que);
if(numberOfRuns == 0){
th.interrupt();
Intent myIntent = new Intent(Loop.this, LOOP_OVER.class);
startActivity(myIntent);
super.onDestroy();
finish();
}
th = new Thread(new Runnable() {
public void run() {
genNextSet();
while (progressStatus < 100) {
progressStatus += 1;
// Update the progress bar and display the
//current value in the text view
handler.post(new Runnable() {
public void run() {
circleProgress.setProgress(progressStatus);
progressBar.setProgress(progressStatus);
textView.setText(progressStatus+"/"+progressBar.getMax());
}
});
try {
runOnUiThread(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
myView.setText(Que);
}
});
// Sleep for 200 milliseconds.
//Just to display the progress slowly
Thread.sleep(30);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
progressStatus = 0;
Progress(numberOfRuns - 1);
}
});
th.start();
}
private void genNextSet() {
// so some cool here!
}
}
You can think of a class variable that is shared among all threads.
Try to add something like this:
private Boolean LOOP = true;
then
while (progressStatus < 100 && LOOP) {
and
#Override
public void onBackPressed() {
LOOP = false
}
also
if(LOOP == true){
// call intent
}
finish();
Your activity does not get destroyed, if you press the "Back"-key, thus onDestroy() will not be called.I'd override onBackPressed(), if I where you.Alternatively, you could try to put it into the onPause()-method.
You haven't override the back button pressed..try this
#Override
public void onBackPressed() {
th.interrupt();
Loop.this.finish();
Thread.currentThread().interrupt();
super.onBackPressed();
// add finish() if you want to kill current activity
}
I have an activity (not my main activity) that plays some sounds and draw some graphics in a runnable thread. There is an imagebutton with which I'm supposed to suspend and resume the thread. But whatever I try the thread just runs on. I'm totally stuck! Please help.
public class PlayInterval extends Activity {
private Handler customHandler;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_playinterval);
final ImageButton playPauseButton = (ImageButton) findViewById(R.id.playPauseButton);//Play/Pause
playPauseButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
onPlayPauseClicked(playPauseButton,(String)playPauseButton.getTag());
}
});
customHandler = new Handler();
new Thread(new Task()).start();
}
#Override
public void onBackPressed() {
customHandler.removeCallbacksAndMessages(null);
finish();
}
class Task implements Runnable {
#Override
public void run() {
// Do really cool stuff
// and even cooler stuff
customHandler.postDelayed(this, 100);
}
}
private void onPlayPauseClicked(ImageButton playPauseButton, String status) {
if (status == "playing") {
playPauseButton.setTag("paused");
customHandler.removeCallbacksAndMessages(null); //TODO suspend here not working!
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
playPauseButton.setImageResource(getResources().getIdentifier("pause_image", "drawable", getPackageName()));
} else {
playPauseButton.setImageDrawable(getDrawable(getResources().getIdentifier("pause_image", "drawable", getPackageName())));
}
} else {
playPauseButton.setTag("playing");
customHandler.postDelayed(this, 100); //TODO resume here not working!
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
playPauseButton.setImageResource(getResources().getIdentifier("play_image", "drawable", getPackageName()));
} else {
playPauseButton.setImageDrawable(getDrawable(getResources().getIdentifier("play_image", "drawable", getPackageName())));
}
}
}
}
I never did get an answer so after trial and error I came up with this. I've red quite alot here on StackOverflow and what I understand this is NOT the way it is supposed to be done. But it is working very well, so if anyone could explain why one shouldn't use syncronized methods like this and provide a better answer I would be thankful.
Cheers
public class PlayInterval extends Activity {
private Handler customHandler;
Boolean isRunning;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_playinterval);
final ImageButton playPauseButton = (ImageButton)findViewById(R.id.playPauseButton);//Play/Pause
playPauseButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
onPlayPauseClicked(playPauseButton);
}
});
customHandler = new Handler();
isRunning=true;
new Thread(new Task()).start();
}
#Override
public void onBackPressed() {
customHandler.removeCallbacksAndMessages(null);
finish();
}
class Task implements Runnable {
#Override
public void run() {
if (isRunning == true){
// Do really cool stuff
// and even cooler stuff
} else {
// it is paused
}
customHandler.postDelayed(this, 100);
}
private syncronized void onPlayPauseClicked(ImageButton playPauseButton) {
if (isRunning==true) {
isRunning=false;
playPauseButton.setImageResource(getResources().getIdentifier("play_image", "drawable", getPackageName()));
} else {
isRunning=true;
playPauseButton.setImageResource(getResources().getIdentifier("pause_image", "drawable", getPackageName()));
}
}
}
So I am writing an Android application which will do a count down when the user presses a button. A thread runs the count down. My problem is that when I pause the application I want the thread to stop counting and then resume once the application is back. My notify is not working correctly. Help thanks!
public class MainActivity extends Activity {
private TextView mText;
private EditText mUserInput;
private CounterThread mCounterThread;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mText = (TextView)findViewById(R.id.text);
mUserInput = (EditText)findViewById(R.id.userInput);
mCounterThread = new CounterThread();
}
#Override
public synchronized void onPause(){
super.onPause();
mCounterThread.running = false;
}
#Override
public synchronized void onResume(){
super.onResume();
mCounterThread.running = true;
notify();//seems like this does nothing!
}
public void startCounterThread(){
mCounterThread.start();
}
public void button_handler(View v){
startCounterThread();
}
public void updateSeconds(final long seconds){
Runnable UIdoWork = new Runnable(){
public void run(){
String time = String.valueOf(seconds);
mText.setText("Your file will open in " + time + " seconds");
}
};
runOnUiThread(UIdoWork);
}
private class CounterThread extends Thread{
int count = 10;
boolean running = true;
#Override
public synchronized void run(){
while(count != 0){
while(!running){
try{
wait();//wait() will wait forever
//I don't want to put a time since
//I have no clue when the user will resume again
}catch(InterruptedException e){
e.printStackTrace();
}
}
try{
Thread.sleep(1000);
}catch(InterruptedException e){
e.printStackTrace();
}
updateSeconds(count--);
}
}
}
Slightly modified code:
public class MainActivity extends Activity {
private TextView mText;
private EditText mUserInput;
private CounterThread mCounterThread;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_2);
mText = (TextView) findViewById(R.id.text);
mUserInput = (EditText) findViewById(R.id.userInput);
mCounterThread = new CounterThread();
mCounterThread.start();
}
#Override
public synchronized void onPause() {
super.onPause();
mCounterThread.onPause();
}
#Override
public synchronized void onResume() {
super.onResume();
mCounterThread.onResume();
}
public void startCounterThread() {
mCounterThread.start();
}
public void button_handler(View v) {
startCounterThread();
}
public void updateSeconds(final long seconds) {
Runnable UIdoWork = new Runnable() {
public void run() {
String time = String.valueOf(seconds);
mText.setText("Your file will open in " + time + " seconds");
}
};
runOnUiThread(UIdoWork);
}
private class CounterThread extends Thread {
private int count = 10;
private final Object lock = new Object();
private volatile boolean isRunning = true;
public void onResume() {
if(!isRunning){
isRunning = true;
synchronized (lock){
lock.notify();
}
}
}
public void onPause() {
isRunning = false;
}
#Override
public void run() {
while (count != 0) {
synchronized (lock) {
if (!isRunning) try {
lock.wait();
} catch (InterruptedException e) {
//
}
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
//
}
updateSeconds(count--);
}
}
}
}
your field running must be marked as volatile. It basically means that several threads could change it and all threads will see it.
do not expose monitor objects out of a Thread or a Runnable. It's quite bad idea to use activity as a monitor. It's quite bad idea to pass reference of activity anywhere.
you used different monitor objects: Thread and Activity. Use one inside thread.
It makes sense that is not working because wait() and notify() work over an object that is used as a lock. When you run wait() in your run() method, you are using an instance of CounterThread as a lock, but when you run notify() inside your onResume() method, you are using an instance of MainActivity. CounterThread will never get notified. Your alternative is (in your onResume() method):
...
synchronized(mCounterThread) {
mCounterThread.notify();
}
...
This is the code of my testing app:
public class MainActivity extends Activity
{
private TextView text;
private Button start;
private Button stop;
private TestThread Points;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
text = (TextView) findViewById(R.id.mainTextView1);
start = (Button) findViewById(R.id.mainButton1);
stop = (Button) findViewById(R.id.mainButton2);
Points = new TestThread();
start.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View p1)
{
if (! Points.isAlive())
{
Points.start();
}
}
});
stop.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View p1)
{
if (Points.isAlive())
{
Points.stop();
}
}
});
}
public class TestThread extends Thread
{
private String points;
#Override
public void run()
{
for (int a = 0; a < 3; a++)
{
try
{
if (a == 0) points = ".";
else if (a == 1) points = "..";
else if (a == 2) {
points = "...";
a = -1;
}
runOnUiThread(new Runnable()
{
#Override
public void run()
{
text.setText(points);
}
});
Thread.sleep(350);
} catch (InterruptedException e) {}
}
}
}
}
When I click on Start button the thread starts successfully but when I click on Stop button the app crashes...
How can i stop the thread successfully without force closing?
Thanks a lot
Thread.stop() function is deprecated and should not be used to stop a thread.
this is according to the java docs.
a good way to stop a thread is make it exit its run method.
a simple way to achive this is by adding a boolean member to your thread class:
public class TestThread extends Thread
{
private String points;
private boolean keepRunning = true;
public cancel(){
keepRunning = false;
}
#Override
public void run()
{
for (int a = 0; a < 3; a++)
{
if(!keepRunning) break;
try
{
if (a == 0) points = ".";
else if (a == 1) points = "..";
else if (a == 2) {
points = "...";
a = -1;
}
runOnUiThread(new Runnable()
{
#Override
public void run()
{
text.setText(points);
}
});
Thread.sleep(350);
} catch (InterruptedException e) {}
}
}
}
call the TestThread.cancel() function in your stop button onClick method.
Other than adding a Boolean to stop it I believe you could catch InterruptException and just call Thread.interrupt(); which would exit the loop this ending the thread
I was creating a splash screen in android using Thread.sleep(). (I know the another method - using handler, but I have to use this method for now.)
My code is as follows:
public class SplashScreen extends Activity {
Thread t;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_spash_screen);
new myclass();
}
class myclass implements Runnable{
myclass()
{
t = new Thread();
t.start();
}
public void run()
{
try{
Thread.sleep(1000);
Intent i = new Intent(getApplicationContext(), MainActivity.class);
startActivity(i);
finish();
}
catch(InterruptedException e){
System.out.println("thread interrupted");
}
}
}
}
It does not show any error, but splash screen stuck to the screen.
After 1s, it did not start another intent.
If you know the mistake then please help me.
run method of runnable is not called because you are not passing runnable to Thread constructor. so pass it as:
t = new Thread(this);
Try this,I always use this code in my Splash Activities.
public class SplashScreen extends Activity
{
private Thread mSplashThread;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.splash_screen);
mSplashThread = new Thread()
{
#Override
public void run()
{
try
{
synchronized (this)
{
wait(2000);
}
}
catch(InterruptedException ex) {
ex.printStackTrace();
}
finish();
startActivity(new Intent(getApplicationContext(),MainActivity.class));
}
};
mSplashThread.start();
}
#Override
public boolean onTouchEvent(MotionEvent evt)
{
if (evt.getAction() == MotionEvent.ACTION_DOWN)
{
synchronized (mSplashThread)
{
mSplashThread.notifyAll();
}
}
return true;
}
}