My problem is...
I have 2 events.. onCreate and Onclick. I have a thread running inside onCreate and i have to stop it inside onClick. Is this possible?
If yes, please provide me with some hints/ code snippets how to implement this.
My code inside onCreate event is this:-
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_screen);
button = (Button) findViewById(R.id.btn);
button.setOnClickListener(this);
try{
bright = Settings.System.getInt(getContentResolver(),
Settings.System.SCREEN_BRIGHTNESS);
}catch(Exception ex){
ex.printStackTrace();
bright = 1.0f;
}
lp = getWindow().getAttributes();
new Thread(new Runnable(){
#Override
public void run() {
// TODO Auto-generated method stub
while (true) {
try {
Thread.sleep(10000);
mHandler.post(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
lp.screenBrightness= dim;
getWindow().setAttributes(lp);
// SLEEP 2 SECONDS HERE ...
final Handler handler = new Handler();
Timer t = new Timer();
t.schedule(new TimerTask() {
public void run() {
handler.post(new Runnable() {
public void run() {
lp.screenBrightness=bright;
getWindow().setAttributes(lp);
}
});
}
}, 2000);
}
});
} catch (Exception e) {
// TODO: handle exception
}
}
}
}).start();
}
this activity is running inside a loop. And i want to stop this wen i click on the button. It seems that i cannot call the Thread.interrupt() method inside the button onclick event. How do i proceed with this?
Declare an boolean mRunnning in your class, this is like a flag, and custom running thread will depend on this to know if it has been cancelled.
As usual, you have a loop in your thread, instead of while(true) do while(mRunning).
Also, you are making your thread sleep, during sleep, thread won't be able to check on mRunning variable, you will have to call interrupt() on thread object to make it stop.
It will be better to use a variable to hold thread reference Thread t = new Thread(....
So, now to stop your thread you have to call mRunning = false and then t.interrupt().
according to your current situation based on previous answer comment . you r trying like:
myThread = new Thread(new Runnable
right?
then u should also delete .start(); part of your previous coding. then write:
myThread.start();
u should declare myThread as global in your class, so that u can access this thread from anywhere in your class. now u can stop thread in onClick
u should combine this answer and User117 s answer together .
If you create a reference you can access it from everywhere in you class. So, in the class body ad something like
Thread thrd
Just like you would do so with a Button, TextView, or whatever. Then in the onCreate method add the reference like
thrd = new Thread(new Runnable(){
Now you have a reference to your thread you can use everywhere in your class.
instead of
while(true)
inside the run() Method, declare a boolean variable to true and change it after onClick. For example:
private boolean shouldRun = true;
then in the run() method:
#Override
public void run() {
// TODO Auto-generated method stub
while (shouldRun==true) {
.
.
.
and in your onClick:
#override
public void OnClick(View v){
shouldRun=false;
.
.
.
Related
Where timer is a textview and throws error during runtime and UI comes out saying unfortunately has stopped.Have attached error mess link below.Plz help not understanding where I am going wrong
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.level_twolayout);
Thread t1 = new Thread(new Runnable() {
public void run() {
for (int i = 0; i < 10; i++) {
try {
Thread.sleep(1000);
} catch (Exception e) {
}
Timer.setText("Hello");
}
}
});
t1.start();
}
You must update UI from main thread.
Use this code. in place of Timer.setText("Hello");
// verify we are indeed updating UI on main thread.
runOnUiThread(new Runnable() {
#Override
public void run() {
// go ahead and update UI
Timer.setText("Hello");
}
});
runOnUiThread is an Activity method. See http://developer.android.com/reference/android/app/Activity.html#runOnUiThread%28java.lang.Runnable%29.
You need to call MyActivityName.this.runOnUiThread() or more simply just runOnUiThread() as "this" will point to the scope of the Runnable you are creating and not your Activity.
Lastly, "Timer" may not be the best name for your TextView.
I have a SetContentView(R.layout.camera);
I want this layout to be start executing after some milliseconds....till then it should be blank. How can I achieve this in android?
For this Write your onCreate() like this..Then it will work..
Thread t = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
t = new Thread(new Runnable() {
#Override
public void run() {
try {
t.sleep(5000);
runOnUiThread(new Runnable() {
public void run() {
setContentView(R.layout.activity_main);
}
});
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
t.start();
}
you can use handler for make delay
Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
//setcontentview
}
};
in oncreate methode
Message m = Message.obtainMessage();
handler.sendMessageDelayed(m, delayMillis);
Your activity will not be visible unless onResume() will get called, Do some operation in main Thread or onCreate() Method it will block your main thread and UI will not be displayed until your operation gets completed.
Create root View with all the components and visibility set to INVISIBLE or GONE and then show it after delay. You can use Handler and postDelayed to execute a code after delay.
So I have an activity which runs a simple snakes and ladders game, and I want to allow the player to click a button and move, which would subsequently be followed by the computer moving. My problem is, that once the player moves, the computer immediately makes its move.
Instead I want the activity to wait before the computer makes its move. I've looked around a lot and found that waiting involves using a thread, but I have failed to implement it without my app crashing
My attempt at declaring a thread:
final Runnable runnable = new Runnable() {
#Override
public void run()
{
while (true)
{
try
{
Thread.sleep(5000);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
}
}
};
Thread thread= new Thread(runnable);
My onClick() method for the button:
Button rollButton = (Button) (findViewById(R.id.rollButton));
rollButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//executes only if current player is a human
if(GAME_BOARD.getCurrentPlayer().isHuman()) {
GAME_BOARD.rollDie(); // rolls the die
showDie(GAME_BOARD); // displays die on screen
GAME_BOARD.move(); // moves the player and sets next player as current player
playerTurn.setText(GAME_BOARD.getCurrentPlayer().getName() +"'s turn");// sets TextView to display who's player's turn it is
thread.start();
if(!GAME_BOARD.getCurrentPlayer().isHuman()) {
GAME_BOARD.rollDie();
showDie(GAME_BOARD);
GAME_BOARD.move();
playerTurn.setText(GAME_BOARD.getCurrentPlayer().getName() +"'s turn");
}
}
}
});
So again, my question is, how do I make it so that before the second if statement executes, the activity waits, say 4 seconds?
you can use an Handler.postDeleayed. You have to provide a Runnable to execut and the delay period in milliseconds. The Runnable will be executed on the UI Thread
You can use Handle to post your task defined in runnable after some delay
use this
Inside Activity define
Handler hand = new Handler();
and define your task in runnable like this
Runnable run = new Runnable() {
#Override
public void run() {
**your Task here.......**
}
};
In on click event
btnStartShow.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
hand.postDelayed(run,3000); // For delay three seconds
}
});
also remove all pending messages by calling following sentence at appropriate place
hand.removeCallbacksAndMessages(null);
Use a CountDownTimer:
CountDownTimer timer = new CountDownTimer(4000, 1000) {
#Override
public void onFinish() {
*function containing the second statement*
}
#Override
public void onTick(long millisLeft) {
// not ticking
}
};
and in the onClick method in the click listener use:
timer.start();
Try the following,
rollButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Runnable runnable = new Runnable() {
#Override
public void run() {
// whatever you would like to implement when or after clicking rollButton
}
};
rollButton.postDelayed(runnable, 5000); //Delay for 5 seconds to show the result
}
I am working on a Testing Project for me , just so I could learn more , so now I need to update the text of a TextView constantly every 250 milliseconds through a for(;;) loop , it happens after a Button click ... My problem is that whenever I press that button my app freezes (Yes my button is totally working , verified through previous testings) , I am using a handler to the Main thread doesn't get affected while the Runnable is up ... Here is my code of the Button and Handler ...
final Handler handler = new Handler();
B3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
handler.post(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
for(;;){
String a = Shells.sendSingleCommand("free");//Here I send a command "free" and it returns its output
text.setText(a);//text is my TextView which is used through my experimentations ...
synchronized(this){
try{
wait(250);
}catch(Exception e){
}
}
}
}
});
}
});
If you need anymore info ask please :)
use handler.postDelayed for updating textview constantly every 250 milliseconds instead of using for loop to avoid freeze current Activity as :
Handler handler=new Handler();
B3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
handler.post(runnable);
}
});
Runnable runnable=new Runnable(){
#Override
public void run() {
String a = Shells.sendSingleCommand("free");
text.setText(a);
handler.postDelayed(runnable, 250);
}
};
Android doesnt allow you to do long tasks in the main thread. If you need to do something like this I recommend moving the for loop and depdendent code into a separate thread..
I have to display some data after every 10 seconds. Can anyone tell me how to do that?
There is an another way also that you can use to update the UI on specific time interval. Above two options are correct but depends on the situation you can use alternate ways to update the UI on specific time interval.
First declare one global varialbe for Handler to update the UI control from Thread, like below
Handler mHandler = new Handler();
Now create one Thread and use while loop to periodically perform the task using the sleep method of the thread.
new Thread(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
while (true) {
try {
Thread.sleep(10000);
mHandler.post(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
// Write your code here to update the UI.
}
});
} catch (Exception e) {
// TODO: handle exception
}
}
}
}).start();
Probably the simplest thing to do is this:
while(needToDisplayData)
{
displayData(); // display the data
Thread.sleep(10000); // sleep for 10 seconds
}
Alternately you can use a Timer:
int delay = 1000; // delay for 1 sec.
int period = 10000; // repeat every 10 sec.
Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask()
{
public void run()
{
displayData(); // display the data
}
}, delay, period);
Andrahu was on the right track with defining a handler. If you have a handler that calls your update functions you can simply delay the message sent to the handler for 10 seconds.
In this way you don't need to start your own thread or something like that that will lead to strange errors, debugging and maintenance problems.
Just call:
Handler myHandler = new MyUpdateHandler(GUI to refresh); <- You need to define a own handler that simply calls a update function on your gui.
myHandler.sendMessageDelayed(message, 10000);
Now your handleMessage function will be called after 10 seconds. You could just send another message in your update function causing the whole cycle to run over and over
There is Also Another way by Using Handler
final int intervalTime = 10000; // 10 sec
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
//Display Data here
}
}, intervalTime);
There is a Simple way to display some data after every 10 seconds.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_launcher);
ActionStartsHere();
}
public void ActionStartsHere() {
againStartGPSAndSendFile();
}
public void againStartGPSAndSendFile() {
new CountDownTimer(11000,10000) {
#Override
public void onTick(long millisUntilFinished) {
// Display Data by Every Ten Second
}
#Override
public void onFinish() {
ActionStartsHere();
}
}.start();
}
Every 10 seconds automatically refreshed your app screen or activity refreshed
create inside onCreate() method i tried this code will work for me
Thread t = new Thread() {
#Override
public void run() {
try {
while (!isInterrupted()) {
Thread.sleep(1000);
runOnUiThread(new Runnable() {
#Override
public void run() {
//CALL ANY METHOD OR ANY URL OR FUNCTION or any view
}
});
}
} catch (InterruptedException e) {
}
}
};t.start();