Develop Reference

Best way handle result from thread on UI

I want to save data to DB in new Thread and after that show toast on the UI.
Method for saving:
public void addToBasket(String text) {
new Thread(() -> {
//emulate save
try {
Thread.sleep(5000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
//after that I need say ti UI thread - show Toast!
}).start();
}
I call this method:
BasketService.me().addToBasket(result.getContents());
I do now want use AsyncTask for this. Please tell me the best way to implement such tasks

batter to use:
runOnUiThread(new Runnable() {
public void run() {
//Do what ever you want do man
}
});
runOnUiThread() method to manipulate your UserInterface from background threads.

In case of callback from a nonUi thread to Ui thread you can use runOnUiThread()(As specified above) or Handler. Below is a example of using handler.
protected static final Handler mainThreadHandler = new Handler(Looper.getMainLooper());
protected void onSuccessInMainThread(final R result, final Bundle bundle) {
mainThreadHandler.post(new Runnable() {
#Override
public void run() {
callback.onSuccess(result, bundle);
}
});
}
protected void onErrorInMainThread(final Exception error) {
mainThreadHandler.post(new Runnable() {
#Override
public void run() {
callback.onError(error);
}
});
}

CountDownTimer in EditText lag in the last second

I would like to set an EditText with a timer thanks to CountDownTimer.
My EditText write second by second the number 3 and 2 but for the 1 there is a lag (it take 1,5 to 2 seconds).
Maybe I do it wrong.
This is my code :
CountDownTimer mCountDownTimer = new CountDownTimer(4000, 1000) {
#Override
public void onTick(long millisUntilFinished) {
txt_timer.setText(String.valueOf(millisUntilFinished / 1000));
}
#Override
public void onFinish() {
txt_timer.setText("GO");
}
};
mCountDownTimer.start();

That is because the UI thread is doing too much work. Try running a new thread on the UI thread itself:
runOnUiThread(new Runnable() {
public void run()
{
//Insert your code
}
});
}
Let me know if you can;t get this to work!

The memory in the device cause the problem. I found a solution running a new thread.
I have to declare int i=4; before and use this code :
new Thread() {
public void run() {
while (i-- > 1) {
try {
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
txt_timer.setText(String.valueOf(i));
}
});
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
txt_timer.setText("GO");
}
}.start();

Adding and clearing window flags inside a thread

I want to add and clear window flag inside a thread but not working. Basically i want my thread to keep the screen on for two seconds and then clear the screen on flag.
Here's my code:
public class WriteCommThread extends Thread {
private long time=2000;
public WriteCommThread(float count) {
time = (long) count;
}
public void run() {
while(connectionUnAbort==true){
// Lock screen
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
slleep();
//Unlock screen
getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
connectionUnAbort=false;
}
}
public void slleep(){
try {
Thread.sleep(time);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

I solved it after doing research, i am posting the referred link.
Answer Link
Here's my solution to my problem and it worked perfectly. I added these runnable classes in my background thread (run method). And after sleeping i could clear the flag to keep the screen on.
runOnUiThread(new Runnable() {
public void run() {
//stuff that updates ui
MainActivity.this.getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
}
});
runOnUiThread(new Runnable() {
public void run() {
//stuff that updates ui
MainActivity.this.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
}
});

Updating UI using a Handler freezes my app

I am trying to make a clock, using a TextView :)
Someone here told me that I couldn't use normal threads to change the UI, but Handler or AsyncTask. I managed to get it working a few days ago, but was not a consistent thread.
Now what I want is a consistent thread that is always changing the text of my Textview. I tried using this, but didn't work, any help?
private void startClock() {
new Handler().postDelayed(new Runnable(){
#Override
public void run() {
while (true) {
final long millis = System.currentTimeMillis() - MainActivity.startedAt;
clock.setText("" + millis);
runOnUiThread (new Runnable() {
#Override
public void run() {
clock.setText("" + millis);
}
});
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}, 2000);
}

you should get rid of:
while(true) {
....
sleep(1000);
...
}
because this get your thread stuck forever. your program should work like this:
private Handler mHandler = new Handler();
#Override
public void onResume() {
super.onResume();
mHandler.removeCallbacks(mUpdateClockTask);
mHandler.postDelayed(mUpdateCLockTask, 100);
}
#Override
public void onPause() {
super.onPause();
mHandler.removeCallbacks(mUpdateClockTask);
}
private Runnable mUpdateClockTask = new Runnable() {
public void run() {
updateClock();
mHandler.postDelayed(mUpdateClockTask, 2000);
}
};
and inside updateClock() you do all your UI updates.

Look here for an example https://stackoverflow.com/a/11140429/808940
Also note that you have a duplicate line in your code:
clock.setText(""+millis);
It appears both in the runOnUiThread and in the main handler, it should only appear in the runOnUiThread runnable

Handler.postdelayed

I am using handler.postDelayed method to create some delay for some animation stuff.
With that i am playing some song as well using Mediaplayer. User can exit this action class by clicking next. But on next screen the same song is continuing even though i called stop method in the next button's onclicklistener.
Is it due to the timedelay that is added which gets executed after the next activity is loaded. Any idea?
handler.postDelayed(new Runnable() {
public void run() {
mp = MediaPlayer.create(getApplicationContext(), R.raw.num2);
mp.start();
imageView1.setImageResource(R.drawable.countcat2);
}
}, 2000);

Did you add a Log to see if run() gets called? I would assume that your handler gets unregistered; after all, postDelayed will wait until the looper kicks in again.
I assume your animation is faster than those 2000ms? You wouldn't be able to have your handler called anyway after your activity is gone, it's accessing imageView1 which I presume is destroyed in onDestroy.
You could consider adding a flag that will force the operation to be called immediately in onDestroy, and/or you could use a Timer. In case of the timer, be sure to not use something like imageView1 after it has been destroyed.

Use threads. And then stop it with an interruption:
Public Thread getThread(final Handler handle, int delay)
{
return new Thread()
{
#Override
public void run()
{
try
{
synchronized(this)
{
Thread.sleep(delay);
handle.post(new Runnable()
{
#Override
public void run()
{
"the code to be exec."
}
});
}
}
catch(Exception e)
{
e.printStackTrace();
}
};
};
}
Or you can use use the postDelayed function
Public Thread getThread(final Handler handle, int delay)
{
return new Thread()
{
#Override
public void run()
{
try
{
synchronized(this)
{
handle.postDelayed(new Runnable()
{
#Override
public void run()
{
"the code to be exec."
}
}, delay);
}
}
catch(Exception e)
{
e.printStackTrace();
}
};
};
}
you will find that there's a little difference between this two methods. To interrupt it, do something like this:
Thread t = getThread(handle, delay);
t.start();
if(t != null)
{
if (t.isAlive())
{
t.interrupt();
}
}
Hope I have helped.