I want to make a program which will tell me the number of seconds I kept holding the button.
for example if I clicked the button for 5 seconds, it should tell me the button remained pressed for 5 seconds.
is this achievable in android?
This is how I tried, didn't work because when I put the while loop in, the button stays clicked even I press it for just one second. The program doesn't crash but the button remains clicked and I think it freezes.
thread = new HandlerThread("");
btn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
while(btn.isPressed())
{
try {
thread.sleep(1000);
total = total++;
temp = temp++;
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
Toast.makeText(MainActivity.this, ""+temp+" "+total, 0).show();
}
});
You could use time stamps, and an OnTouchListener to achieve this.
When your OnTouchListener receives an ACTION_DOWN event, store the first time stamp. When it receives an ACTION_UP event, store the second time stamp and calculate the difference between the two.
As mentioned by Raghunandan, you should never block on the UI thread using calls such as thread.sleep, as this will cause the UI to stop responding, and in some cases can cause the program to be killed because of this.
Here is an example of what I've outlined above. Please note, this code was written from memory, and has not been tested, but you should get the general gist of it.
btn.setOnTouchListener(new OnTouchListener() {
private long firstTouchTS = 0;
#Override
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction()==MotionEvent.ACTION_DOWN) {
this.firstTouchTS = System.currentTimeMillis();
} else if (event.getaction()==MotionEvent.ACTION_UP) {
Toast.makeText(MainActivity.this,((System.currentTimeMillis()-this.firstTouchTS)/1000)+" seconds",0).show();
}
}
});
References: OnTouchListener MotionEvent
thread.sleep(1000);
Calling sleep on the ui thread hence it freezes. Do not call sleep on the ui thread. It blocks the ui thread.
Read
http://developer.android.com/training/articles/perf-anr.html.
Use a Handler if you want to repeat some task
so I am building an experiment app where the background will change colour at random intervals.
I am stuck on the background change.
I have working code that changes the background colour, but when I put it in a thread/ try and catch bracket, the application is forced to close and doesnt give me an error?
Here is the code that works when used in the oncreate method:
View view = this.getWindow().getDecorView();
view.setBackgroundColor(Color.RED);
But when I want to make it "sleep" for 1 second and then change it to red, it bombs out.
Please note that this method is a separate method from the oncreate and is called from within there and will not work for some reason?
public void changeBackground(final View v){
Thread timer = new Thread(){
public void run(){
try{
sleep(1000);
}catch (InterruptedException e) {
e.printStackTrace();
}finally{
v.setBackgroundColor(Color.RED);
}
}
};
timer.start();
}
What am I doing wrong?
What I need:
when the app starts, it must wait for 1 second and then change the background colour without it bombing out.
Thanks in advance!
You cannot access UI thread from your custom thread. You have to run your runnable in UI thread. Change your changeBackground method to the following,
public void changeBackground(final View v) {
Thread timer = new Thread() {
public void run() {
try {
sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
v.setBackgroundColor(Color.RED);
}
}
};
this.runOnUiThread(timer);
}
Or you can use Asynctask, this handles that issue for you. Here, and here.
Manipulate view state on UI thread:
v.post(new Runnable() {
#Override
public void run() {
v.setBackgroundColor(Color.RED);
}
});
More about it: http://developer.android.com/guide/components/processes-and-threads.html
UI operations can't be done in a Thread
v.setBackgroundColor(Color.RED);
Remove above line from finally and Use a runOnUIthread() to update UI in Finally.
and your final code will look like this
public void changeBackground(final View v){
Thread timer = new Thread(){
public void run(){
try{
sleep(1000);
}catch (InterruptedException e) {
e.printStackTrace();
}finally{
runOnUiThread(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
v.setBackgroundColor(Color.RED);
}
});
}
}
};
timer.start();
}
Solutions to fix this issue:-
Update you App
Clear Gmail Storage Data
Clear App Cache and Data
Reset App Preferences
Reset Smartphone Factory Settings
I found these steps with the help of YouTube.
Here is that link:-
youtube.com/watch?v=fx8Fv8RXag8
I am developing app and I need that my app will be doing two actions at the same time. For example - I can drag marker and the map will be scrolling at the same time.
I tried to update map while dragging marker, everything would be okay, except thing that when thread starts, maps starts scrolling continuously and I cand do anything more. Here is the code, I call it in onCreate() method. I tried to do Runnable and AsyncTask and the results were the same. Any suggestions?
private void update() {
new Thread() {
public void run() {
while (true) {
runOnUiThread(new Runnable() {
#Override
public void run() {
while (drag)
mMap.animateCamera(CameraUpdateFactory.scrollBy(10, 0), 2, null);
}
});
try {
Thread.sleep(2);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}.start();
}
You don't have the code to interrupt your thread. That's why your map keep scrolling. Try to use drag event to drive this animation, and add some code to terminate the thread at some point.
I have an app where I need to have a delay after each touch in an ImageButton.
I tried the Thread.sleep() method, but I am not sure if this is the best way to deal with it.
What do you guys recommend?
Any help is appreciatted!
ONE MORE THING: I want the content of the onTouch() event to be fired THEN I want to delay "X" seconds the next onTouch() event. It's like to prevent the user to click too many times in the button.
Since all touch events are handled by UI thread, Thread.sleep() will block your UI thread which is (I hope) not what you are looking for.
I think the most correct way to solve your problem would be using postDelayed(Runnable, long) interface in your onClick handler which allows your to delay execution:
#Override
public void onClick(View v)
{
postDelayed(new Runnable()
{
#Override
public void run()
{
// do your stuff here
}
}, 10000); //10sec delay
}
UPDATE:
If you want user to prevent clicking too fast on your image view, I strongly recommend go with onClick rather than onTouch (unless there are serious reasons for that)
However, please see the code snippet which might help you:
private boolean blocked = false;
private Handler handler = new Handler();
#Override
public boolean onTouchEvent(MotionEvent event)
{
if (event.getAction() == MotionEvent.ACTION_DOWN)
{
if (!blocked)
{
blocked = true;
handler.postDelayed(new Runnable()
{
#Override
public void run()
{
blocked = false;
}
}, 1000);
} else
{
return false;
}
}
return super.onTouchEvent(event);
}
I would like a ScrollView to start all the way at the bottom. Any methods?
you should run the code inside the scroll.post like this:
scroll.post(new Runnable() {
#Override
public void run() {
scroll.fullScroll(View.FOCUS_DOWN);
}
});
scroll.fullScroll(View.FOCUS_DOWN) also should work.
Put this in a scroll.Post(Runnable run)
Kotlin Code
scrollView.post {
scrollView.fullScroll(View.FOCUS_DOWN)
}
scroll.fullScroll(View.FOCUS_DOWN) will lead to the change of focus. That will bring some strange behavior when there are more than one focusable views, e.g two EditText. There is another way for this question.
View lastChild = scrollLayout.getChildAt(scrollLayout.getChildCount() - 1);
int bottom = lastChild.getBottom() + scrollLayout.getPaddingBottom();
int sy = scrollLayout.getScrollY();
int sh = scrollLayout.getHeight();
int delta = bottom - (sy + sh);
scrollLayout.smoothScrollBy(0, delta);
This works well.
Kotlin Extension
fun ScrollView.scrollToBottom() {
val lastChild = getChildAt(childCount - 1)
val bottom = lastChild.bottom + paddingBottom
val delta = bottom - (scrollY+ height)
smoothScrollBy(0, delta)
}
Sometimes scrollView.post doesn't work
scrollView.post(new Runnable() {
#Override
public void run() {
scrollView.fullScroll(ScrollView.FOCUS_DOWN);
}
});
BUT if you use scrollView.postDelayed, it will definitely work
scrollView.postDelayed(new Runnable() {
#Override
public void run() {
scrollView.fullScroll(ScrollView.FOCUS_DOWN);
}
},1000);
What worked best for me is
scroll_view.post(new Runnable() {
#Override
public void run() {
// This method works but animates the scrolling
// which looks weird on first load
// scroll_view.fullScroll(View.FOCUS_DOWN);
// This method works even better because there are no animations.
scroll_view.scrollTo(0, scroll_view.getBottom());
}
});
I increment to work perfectly.
private void sendScroll(){
final Handler handler = new Handler();
new Thread(new Runnable() {
#Override
public void run() {
try {Thread.sleep(100);} catch (InterruptedException e) {}
handler.post(new Runnable() {
#Override
public void run() {
scrollView.fullScroll(View.FOCUS_DOWN);
}
});
}
}).start();
}
Note
This answer is a workaround for really old versions of android. Today the postDelayed has no more that bug and you should use it.
i tried that successful.
scrollView.postDelayed(new Runnable() {
#Override
public void run() {
scrollView.smoothScrollTo(0, scrollView.getHeight());
}
}, 1000);
Here is some other ways to scroll to bottom
fun ScrollView.scrollToBottom() {
// use this for scroll immediately
scrollTo(0, this.getChildAt(0).height)
// or this for smooth scroll
//smoothScrollBy(0, this.getChildAt(0).height)
// or this for **very** smooth scroll
//ObjectAnimator.ofInt(this, "scrollY", this.getChildAt(0).height).setDuration(2000).start()
}
Using
If you scrollview already laid out
my_scroll_view.scrollToBottom()
If your scrollview is not finish laid out (eg: you scroll to bottom in Activity onCreate method ...)
my_scroll_view.post {
my_scroll_view.scrollToBottom()
}
When the view is not loaded yet, you cannot scroll. You can do it 'later' with a post or sleep call as above, but this is not very elegant.
It is better to plan the scroll and do it on the next onLayout(). Example code here:
https://stackoverflow.com/a/10209457/1310343
One thing to consider is what NOT to set. Make certain your child controls, especially EditText controls, do not have the RequestFocus property set. This may be one of the last interpreted properties on the layout and it will override gravity settings on its parents (the layout or ScrollView).
Not exactly the answer to the question, but I needed to scroll down as soon as an EditText got the focus. However the accepted answer would make the ET also lose focus right away (to the ScrollView I assume).
My workaround was the following:
emailEt.setOnFocusChangeListener(new View.OnFocusChangeListener() {
#Override
public void onFocusChange(View v, boolean hasFocus) {
if(hasFocus){
Toast.makeText(getActivity(), "got the focus", Toast.LENGTH_LONG).show();
scrollView.postDelayed(new Runnable() {
#Override
public void run() {
scrollView.fullScroll(ScrollView.FOCUS_DOWN);
}
}, 200);
}else {
Toast.makeText(getActivity(), "lost the focus", Toast.LENGTH_LONG).show();
}
}
});
I actually found that calling fullScroll twice does the trick:
myScrollView.fullScroll(View.FOCUS_DOWN);
myScrollView.post(new Runnable() {
#Override
public void run() {
myScrollView.fullScroll(View.FOCUS_DOWN);
}
});
It may have something to do with the activation of the post() method right after performing the first (unsuccessful) scroll. I think this behavior occurs after any previous method call on myScrollView, so you can try replacing the first fullScroll() method by anything else that may be relevant to you.
Using there is another cool way to do this with Kotlin coroutines. The advantage of using a coroutine opposed to a Handler with a runnable (post/postDelayed) is that it does not fire up an expensive thread to execute a delayed action.
launch(UI){
delay(300)
scrollView.fullScroll(View.FOCUS_DOWN)
}
It is important to specify the coroutine's HandlerContext as UI otherwise the delayed action might not be called from the UI thread.
In those case were using just scroll.scrollTo(0, sc.getBottom()) don't work, use it using scroll.post
Example:
scroll.post(new Runnable() {
#Override
public void run() {
scroll.fullScroll(View.FOCUS_DOWN);
}
});
One possible reason of why scroll.fullScroll(View.FOCUS_DOWN) might not work even wrapped in .post() is that the view is not laid out. In this case View.doOnLayout() could be a better option:
scroll.doOnLayout(){
scroll.fullScroll(View.FOCUS_DOWN)
}
Or, something more elaborated for the brave souls: https://chris.banes.dev/2019/12/03/suspending-views/
A combination of all answers did the trick for me:
Extension Function PostDelayed
private fun ScrollView.postDelayed(
time: Long = 325, // ms
block: ScrollView.() -> Unit
) {
postDelayed({block()}, time)
}
Extension Function measureScrollHeight
fun ScrollView.measureScrollHeight(): Int {
val lastChild = getChildAt(childCount - 1)
val bottom = lastChild.bottom + paddingBottom
val delta = bottom - (scrollY+ height)
return delta
}
Extension Function ScrolltoBottom
fun ScrollView.scrollToBottom() {
postDelayed {
smoothScrollBy(0, measureScrollHeight())
}
}
Be aware that the minimum delay should be at least 325ms or the scrolling will be buggy (not scrolling to the entire bottom). The larger your delta between the current height and the bottom is, the larger should be the delayed time.
Some people here said that scrollView.post didn't work.
If you don't want to use scrollView.postDelayed, another option is to use a listener. Here is what I did in another use case :
ViewTreeObserver.OnPreDrawListener viewVisibilityChanged = new ViewTreeObserver.OnPreDrawListener() {
#Override
public boolean onPreDraw() {
if (my_view.getVisibility() == View.VISIBLE) {
scroll_view.smoothScrollTo(0, scroll_view.getHeight());
}
return true;
}
};
You can add it to your view this way :
my_view.getViewTreeObserver().addOnPreDrawListener(viewVisibilityChanged);
If your minimum SDK is 29 or upper you could use this:
View childView = findViewById(R.id.your_view_id_in_the_scroll_view)
if(childView != null){
scrollview.post(() -> scrollview.scrollToDescendant(childView));
}
This works instantly. Without delay.
// wait for the scroll view to be laid out
scrollView.post(new Runnable() {
public void run() {
// then wait for the child of the scroll view (normally a LinearLayout) to be laid out
scrollView.getChildAt(0).post(new Runnable() {
public void run() {
// finally scroll without animation
scrollView.scrollTo(0, scrollView.getBottom());
}
}
}
}