Develop Reference

Android programming many toggle button using in for loop

My problem is when I click a toggle button, mp3player is playing and when I click off it is stopping. So when I try to run first time it works. But when I click second time it gives IllegalStateException and "E/MediaPlayer(1009): attachNewPlayer called in state 32" error. How can I fix this problem? Thanks .
My code is here:
public class MyButtons extends Activity {
private static final int[] idBtns = { R.id.btn1, R.id.btn2, R.id.btn3,
R.id.btn4, R.id.btn5, R.id.btn6, R.id.btn7, R.id.btn8, R.id.btn9 };
String[] mpUrls = new String[idBtns.length];
ToggleButton[] mbuttons = new ToggleButton[idBtns.length];
MediaPlayer mp3player = new MediaPlayer();
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.mybuttons);
mp3player.setAudioStreamType(AudioManager.STREAM_MUSIC);
for (int i = 0; i < idBtns.length; i++) {
final int k = i;
mbuttons[k] = (ToggleButton) findViewById(idBtns[k]);
mpUrls[k] = "http://www.testsite.com/def-music-"+ (k + 1) + ".mp3";
}
for (int i = 0; i < idBtns.length; i++) {
final int k = i;
mbuttons[k].setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
boolean on = ((ToggleButton) view).isChecked();
if (on) {
try {
mp3player.setDataSource(mpUrls[k]);
mp3player.prepare();
mp3player.start();
mp3player.setLooping(true);
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
Toast.makeText(getApplicationContext(), e.toString(),Toast.LENGTH_LONG).show();
}
} else {
if (mp3player.isPlaying()) {
mp3player.pause();
mp3player.seekTo(0);
}
}// if(on)-else statement's end
}// onClick's end
});
}// for loop's end
}
}
enter image description here

setDataSource have to be called in Idle state. If you click toggle button second time, it's state must not be idle. So you should manage the state in you app using media player listenr and you should make it work accordingly. Anternatively, you can reset mediaplyer every time you start to play. But it propably provides bad user environment.
You can refer document about Valid and invalid states.
https://developer.android.com/reference/android/media/MediaPlayer.html

Android: How the View draw the component?

Android question:
When I set text to a view, when the view will update the UI?
Here is my case 1:
for(int i=0;i< 2000; i++){
aTextView.setText("a"+i);
}
aTextView is a MyTextView, that extends from TextView. I overwirte the onDraw as:
public static int counterP = 0;
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
counterP++;
Log.d("MYButton", "onDraw: " + counterP);
}
From the log, I can see, the printed counterP is not consequent. In the loop, the onDraw method is called only 2-4 times.
I did another test, case 2:
boolean notInit = true;
List<String> cmdList = null;
long stSelfRefresh = 0;
String contentStr;
TextView selfTv;
public void onSelfRefreshTv(View v) {
if (cmdList == null || cmdList.isEmpty()) {
Log.e(TAG, "empty now, reset");
notInit = true;
}
if (notInit) {
cmdList = new ArrayList<String>();
for (int i = 0; i < 2000; i++) {
cmdList.add("a" + i);
}
stSelfRefresh = SystemClock.uptimeMillis();
notInit = false;
selfTv = (MyTextView) findViewById(R.id.mytv);
}
contentStr = cmdList.remove(0);
Log.d(TAG, "contentStr = " + contentStr);
selfTv.setText(contentStr);
if (!cmdList.isEmpty()) {
if (!mHandler.sendEmptyMessage(99)) {
Log.e(TAG, "SKIP my self");
}
} else {
Log.d(TAG, "Cost time: " + (SystemClock.uptimeMillis() - stSelfRefresh));
}
}
private Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case 99:
onSelfRefreshTv(null);
break;
default:
break;
}
}
};
The result of case 2 is the counterP is printed out consequent. 1-2000.
I don't know why the textView is updated for each time?
Do you have any idea for this?
Thanks in advance.
******add case 3***********
for(int i=0;i< 2000;i++){
contentStr = cmdList.remove(0);
mHandler.sendEmptyMessage(100);
}
private Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case 100:
selfTv.setText(contentStr);
break;
default:
break;
}
}
};
******end of case 3**********
The test result for case 3 is similar with case 1.

It looks like you are running your code on the UI Thread.
This means: as long as your code is running, the drawing code can not run. The onDraw() is called after your loop finished counting and only the last value is actually drawn on the display.
It's as simple as that.
If you want something count up on your display, you can use a AsyncTask to move the counting part into a non-UI Thread:
new AsyncTask<Void,Integer, Void>() {
#Override
protected Void doInBackground(Void... voids) {
for (int i =0; i<2000; i++) {
publishProgress(i);
}
return null;
}
#Override
protected void onProgressUpdate(Integer... values) {
aTextView.setText("a"+values[0]);
}
};
Your second case is like this:
You prepare the list with all 2000 elements.
Set the first element of the list to the TextView and remove the item from the list.
Send yourself a message to run on the UI Thread as soon as the system thinks it is appropriate.
Let go the control of the UI Thread.
Your code is actually finished and the system calls onDraw().
The message from 4 gets processed and you start again with 2.
You see that the system gets control over the UI Thread in the middle of your loop. That's why it's counting visibly.
Case 3 is different from 2:
You are sending 2000 messages in on loop without letting the system handle it.

Update UI from running thread

I want to write a download manager app, in the activity I add a progress bar which show the current progress to the user, now if user touch the back button and re-open the activity again this ProgressBar won't be updated.
To avoid from this problem I create a single thread with unique name for each download that keep progress runnable and check if that thread is running in onResume function, if it is then clone it to the current thread and re-run the new thread again but it won't update my UI either, Any ideas !?
#Override
public void onResume()
{
super.onResume();
Set<Thread> threadSet = Thread.getAllStackTraces().keySet();
Thread[] threadArray = threadSet.toArray(new Thread[threadSet.size()]);
for (int i = 0; i < threadArray.length; i++)
if (threadArray[i].getName().equals(APPLICATION_ID))
{
mBackground = new Thread(threadArray[i]);
mBackground.start();
downloadProgressBar.setVisibility(View.VISIBLE);
Toast.makeText(showcaseActivity.this
, "Find that thread - okay", Toast.LENGTH_LONG).show();
}
}
private void updateProgressBar()
{
Runnable runnable = new updateProgress();
mBackground = new Thread(runnable);
mBackground.setName(APPLICATION_ID);
mBackground.start();
}
private class updateProgress implements Runnable
{
public void run()
{
while (Thread.currentThread() == mBackground)
try
{
Thread.sleep(1000);
Message setMessage = new Message();
setMessage.what = mDownloadReceiver.getProgressPercentage();
mHandler.sendMessage(setMessage);
}
catch (InterruptedException e)
{
Thread.currentThread().interrupt();
}
catch (Exception e)
{/* Do Nothing */}
}
}
private Handler mHandler = new Handler()
{
#Override
public void handleMessage(Message getMessage)
{
downloadProgressBar.setIndeterminate(false);
downloadProgressBar.setProgress(getMessage.what);
if (getMessage.what == 100)
downloadProgressBar.setVisibility(View.GONE);
}
};
Download button code:
downloadBtn.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View arg0)
{
downloadProgressBar.setVisibility(View.VISIBLE);
downloadProgressBar.setIndeterminate(true);
downloadProgressBar.setMax(100);
Intent intent = new Intent(showcaseActivity.this, downloadManagers.class);
intent.putExtra("url", "http://test.com/t.zip");
intent.putExtra("receiver", mDownloadReceiver);
startService(intent);
updateProgressBar();
}
});

I'd strongly recommend reading the Android Developer blog post on Painless Threading. As it states, the easiest way to update your UI from another thread is using Activity.runOnUiThread.

remove toast and also destroy or force stop thread

hi i am working on custom toast , and i am able to do that, but after when i move to next activity the thread is running or active of back activity , so what should i do for removing that thread or stop this thread.
my code is given below :
public void customToast(int x, int y, String str) {
if (Util.tipson == true) {
toast = new Toast(getApplicationContext());
toast.setDuration(Toast.LENGTH_SHORT);
toast.setGravity(Gravity.TOP, x, y);
LayoutInflater li = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
toastView = li.inflate(R.layout.toastlayout, null);
toast.setView(toastView);
TextView text = (TextView) toastView.findViewById(R.id.text);
text.setText(str);
// toast.show();
fireLongToast();
}
}
private void fireLongToast() {
t = new Thread() {
public void run() {
int count = 0;
try {
while (true && count < 40) {
try {
toast.show();
sleep(100);
count++;
} catch (Exception e) {
// TODO: handle exception
}
// do some logic that breaks out of the while loop
}
toast = null;
toastView = null;
} catch (Exception e) {
Log.e("LongToast", "", e);
}
}
};
t.start();
}

You Need to stop your thread by yourself. Since java doesn't allow you to use stop() function.
Write class for your Thread as this
public class YourThread extends Thread {
private volatile boolean stopped = false;
public void run() {
int count = 0;
try {
while (true && count < 40 && !stopped) {
try {
toast.show();
sleep(100);
count++;
} catch (Exception e) {
// TODO: handle exception
}
// do some logic that breaks out of the while loop
}
toast = null;
toastView = null;
} catch (Exception e) {
Log.e("LongToast", "", e);
}
}
public void stopThread() {
stopped = true;
}
}
Now when your Activity which has the Thread Finishes stop Your thread
#Override
protected void onDestroy() {
if(isFinishing())
yourThreadVariable.stopThread();
}

Dont know for sure, but you can call the function join of thread in onDestroy of your activity.

To stop the thread you can just use interrupt(). But for better solution I would say not to use Thread. Just create a Handler with Runnable and manage your Runnable using Handler, that would be a nice way as Android has given Handler for managing one or more Runnables.
Creating a Runnable
Runnable runnable = new Runnable() {
#Override
public void run() {
// put your code stuff here
}
};
To start Runnable use
handler.postDelayed(runnable, your_time_in_millis);
To stop Runnable use
handler.removeCallbacks(runnable);

Does finishing the activity have any effect?

I would like to suggest Lalit Poptani method too and implement this:
protected void onStop(){
handler.removeCallbacks(runnable);
super.onStop();
}
The documentation for the method:
onStop,Called when the activity is no longer visible to the user, because another activity has been resumed and is covering this one. This may happen either because a new activity is being started, an existing one is being brought in front of this one, or this one is being destroyed.
http://developer.android.com/reference/android/app/Activity.html

Thread problem in android?

Consider i have one thread as a separate class , for example SimpleThread.java,
class SimpleThread extends Thread {
public SimpleThread(String str) {
super(str);
}
public void run() {
for (int i = 0; i < 10; i++) {
System.out.println(i + " " + getName());
try {
sleep((int)(Math.random() * 1000));
} catch (InterruptedException e) {}
}
System.out.println("DONE! " + getName());
}
}
from my android home.java i need to start the thread,
new SimpleThread("Jamaica").start();
once the loop end i need to shoe the alert,but when i use
authalert = new AlertDialog.Builder(this);
it shows null pointer execption, i need a context over here in thread class , is there any other way to do this.

Hey you should use Handler for this
here is the code ...
ProgressDialog _progressDialog = ProgressDialog.show(this,"Saving Data","Please wait......");
settintAdater();
private void settingAdater(){
Thread _thread = new Thread(){
public void run() {
Message _msg = new Message();
_msg.what = 1;
// Do your task where you want to rerieve data to set in adapet
YourCalss.this._handle.sendMessage(_msg);
};
};
_thread.start();
}
Handler _handle = new Handler(){
public void handleMessage(Message msg) {
switch(msg.what){
case 1:
_progressDialog.dismiss();
listview.setAdapter();
}
}
}

One way of solving your problem is using Handlers, as Sujit suggested. Other way is using AsyncTask. Read here.

the problem is : when you launch the thread, the Compiler will not wait until the thread finish his treatement , he will execute the next instruction ( authalert = new AlertDialog.Builder(this); )
so there are two or three ways to do this :
1) , use handler
2) define your own listener for your thread in order to listen until he finished his treatement ,
3) you can pass the Context of your activity , and at the last line of your run method , display the AlertDialog ( with Activity.runOnUiThread(new Runnable); )

You should read http://www.aviyehuda.com/2010/12/android-multithreading-in-a-ui-environment/ and http://developer.android.com/resources/articles/painless-threading.html
one way would be put a handler in your calling activity:
final mContext=this;
final Handler mHandler=new Handler(){
#Override
public void handleMessage(Message msg) {
int yourIntReturnValue=msg.what;
//cast your object back to whatever it was lets say it was a string:
// String yourString=(String) msg.obj;
//do something like authalert = new AlertDialog.Builder(mContext);
}
};
then
class SimpleThread extends Thread {
Handler mHandler;
public SimpleThread(String str, Handler h) {
super(str);
mHandler=h;
}
public void run() {
for (int i = 0; i < 10; i++) {
System.out.println(i + " " + getName());
try {
sleep((int)(Math.random() * 1000));
} catch (InterruptedException e) {}
}
System.out.println("DONE! " + getName());
Message.obtain(mHandler, someIntRetValue,
"DONE" ).sendToTarget();
}
}