i have one activity Main.java is open in my application, i want to close the activity using broadcast receiver , how to close the activity?
Firstly your Main.java needs to be registered as a receiver. You could register it in Main.java's onResume():
#Override
public void onResume() {
registerReceiver(broadcastReceiver, new IntentFilter(BroadcasterClassName.NAME_OF_ACTION));
}
Then handle the broadcast and finish your activity:
private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(BroadcasterClassName.NAME_OF_ACTION)) {
finish();
}
}
}
You could send a message to the activity which implements Handler.Callback, and handle it there to close the activity.
Quick example:
class Act1 extends Activity implements Handler.Callback {
public static final int CLOSE_ACTIVITY = 54212;
public boolean handleMessage(Message msg) {
if(msg.what == CLOSE_ACTIVITY) {
finish();
}
}
}
And then, since you BroadcastReceiver runs on main thread, in most of the cases. Just send the message via Handler.
new Handler().sendMessage(MessageFactory.createShutdownMsg()).
you could do this:
in your main have:
private static Main mInstance;
onCreate()
{
...
mInstance = this;
}
public static boolean closeActivity()
{
if (mInstance != null)
{
mInstance.finish();
return true;
}
return false;
}
although, this implies only one Main exists at any one time. I think you can achieve that by adding android:noHistory="true" or something similar in the manifest.
Related
How could I know if an activity is the top of stack? I thought about using onResume/onPause, but this is not exactly, as it would fail once the app goes to background.
The fact is that I'm sending a broadcast receiver that is received for all activities (I have a BaseActivity that is extended by all activities and that registers to the broadcast). So, only the activity that is at the top of the stack must react to the broadcast. If I use the isResumed() then it would work always but when the app goes to background. Any idea?
Thanks in advance!
in base activity you register the broadcast Receiver and in receiver function you call one abstract function which one is implemented by all child activities.
The activity which is on top will automatically receive that function call.
Edit sample code:
public abstract class BaseActivity extends AppCompatActivity {
private static final String NOTIFICATION_ARRIVED = "arrived";
public abstract void receivedFunction(Intent intent);
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
displayToast(" received in Base");
receivedFunction(intent);
}
};
public void displayToast(String s) {
Toast.makeText(this,s,Toast.LENGTH_SHORT).show();
}
#Override
public void onResume() {
super.onResume();
registerReceiver(mMessageReceiver, new IntentFilter(BaseActivity.NOTIFICATION_ARRIVED));
}
#Override
public void onPause() {
super.onPause();
unregisterReceiver(mMessageReceiver);
}
}
public class MainActivity extends BaseActivity {
#Override
public void receivedFunction(Intent intent) {
displayToast(" received in child");
}
// do whetever you want . if you ovveride onpause and onResume then call super as well
}
or any other child
public class MainActivity2 extends BaseActivity {
#Override
public void receivedFunction(Intent intent) {
displayToast(" received in child");
}
// do whetever you want . if you ovveride onpause and onResume then call super as well
}
// to broadcast
Intent intent = new Intent(BaseActivity.NOTIFICATION_ARRIVED);
sendBroadcast(intent);
I am learning Android concepts Activity and BroadCastReceiver. I want to update the content of Activity from the BroadtCastReceiver both are in different java class.
It is something like
MyActivity.java and MyBroadtCastReceiver.java
Is this possible to do this in Android ?
A BroadcastReceiver can be used in many ways but when it comes to something as specific as updating the UI components of an Activity, there is little advantage to declaring / defining a BroadcastReceiver in it's own Java class file.
Reasoning - the BroadcastReceiver has to have some prior "knowledge" of the Activity and what it is required to do in order to update the UI. In effect the BroadcastReceiver is tied to the Activity itself and it makes sense to declare / define it as an inner class.
Another important aspect is the Activity needs to be in a "running" (i.e., visible) state in order to guarantee manipulation of UI components. In this case, registering the receiver in onResume() and unregistering in onPause() will help prevent problems.
Using a generic template I'd do something like the following...
class MyActivity extends Activity {
boolean mIsReceiverRegistered = false;
MyBroadcastReceiver mReceiver = null;
// onCreate(...) here
#Override
protected void onResume() {
// Other onResume() code here
if (!mIsReceiverRegistered) {
if (mReceiver == null)
mReceiver = new MyBroadcastReceiver();
registerReceiver(mReceiver, new IntentFilter("YourIntentAction"));
mIsReceiverRegistered = true;
}
}
#Override
protected void onPause() {
if (mIsReceiverRegistered) {
unregisterReceiver(mReceiver);
mReceiver = null;
mIsReceiverRegistered = false;
}
// Other onPause() code here
}
private void updateUI(Intent intent) {
// Do what you need to do
}
private class MyBroadcastReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
updateUI(intent);
}
}
}
EDIT: A couple of extra notes...
The life-cycle of a BroadcastReceiver is between entering and leaving onReceive(...). Once it has returned from onReceive(...) the instance remains in a dormant state waiting for the next broadcast.
Directly related to point 1 - a BroadcastReceiver isn't designed for "heavy lifting". Basically the onReceive(...) method should be kept as simple as possible. Any methods it calls should also be as light-weight as possible...get in, do your stuff, get out then wait for the next broadcast. If updating the UI is going to take some time (perhaps updating a ListView by re-querying a database for a large amount of data for example), consider calling code which performs asynchronously (an AsyncTask for example).
Yes its possible. This is what i do.
Class i send the broadcast from (BackgroundActivity.java):
public static final String BROADCAST_BUFFER_SEND_CODE = "com.example.SEND_CODE";
onCreate(){
bufferIntentSendCode = new Intent(BROADCAST_BUFFER_SEND_CODE);
}
private void sendBufferingBroadcastSendCode() {
bufferIntentSendCode.putExtra("buffering", "1");
sendBroadcast(bufferIntentSendCode);
}
The class it will receive the broadcast(SendCode.java):
onResume(){
registerReceiver(broadcastBufferReceiver, new IntentFilter(BackgroundActivity.BROADCAST_BUFFER_SEND_CODE));
}
// set up broadcast receiver
private BroadcastReceiver broadcastBufferReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent bufferIntent) {
SendCode.this.LoadMessages(alarmNumber);
}
};
I unregister it in onPause
this.unregisterReceiver(broadcastBufferReceiver);
Register a new BroadcastReceiver object in your activity with same intent-filters as your MyBroadtCastReceiver. Since BroadcastReceiver and MyBroadtCastReceiver has same intent-filters both of their onReceive() will be invoked. Whatever update that you want to do in Activity can be done in onReceive of your BroadcastReceiver.
You can do like this:
public class MyActivity extends Activity{
// used to listen for intents which are sent after a task was
// successfully processed
private BroadcastReceiver mUpdateReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
new UpdateUiTask().execute();
}
};
#Override
public void onResume() {
registerReceiver(mUpdateReceiver, new IntentFilter(
YOUR_INTENT_ACTION));
super.onResume();
}
#Override
public void onPause() {
unregisterReceiver(mUpdateReceiver);
super.onPause();
}
// used to update the UI
private class UpdateUiTask extends AsyncTask<Void, Void, String> {
#Override
protected void onPreExecute() {
}
#Override
protected String doInBackground(Void... voids) {
Context context = getApplicationContext();
String result = "test";
// Put the data obtained after background task.
return result;
}
#Override
protected void onPostExecute(String result) {
// TODO: UI update
}
}
}
Squonk-s answer only works, if the Activity is active currently.
If you dont want to declare / define your BroadcastReceiver (BR) in an other Activity, or if you want to make some changes even if the app is not foreground, than your solution would look something like this.
First, you declare the BR, and save, or override the data needed to show in Acitvity.
public class MyBR extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
// override the data. Eg: save to SharedPref
}
}
Then in Activity, you show the data
TextView tv = findViewById(R.id.tv);
tv.setText(/*get the data Eg: from SharedPref*/);
And you should use a Timer to refresh the tv as well:
Timer timer = new Timer();
timer.schedule(new TimerTask() {
#Override
public void run() {
runOnUiThread(new Runnable() {
#Override
public void run() {
TextView tv = findViewById(R.id.tv);
tv.setText(/*get the data Eg: from SharedPref*/);
}
});
}
}, REFRESH_RATE, REFRESH_RATE);
REFRESH_RATE could be something like 1 second, but you decide.
try like this it may help you.
Define this method in activity's oncreate method in which you want to update ui,
BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
//your code to update ui
}
};
LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver, new IntentFilter("giveyourappname"));
Define this action at place from where you want to update ui,
try{
ActivityManager am = (ActivityManager) this .getSystemService(ACTIVITY_SERVICE);
List<RunningTaskInfo> taskInfo = am.getRunningTasks(1);
ComponentName componentInfo = taskInfo.get(0).topActivity;
Log.d("Activity", "Current Activity ::" + taskInfo.get(0).topActivity.getClassName());
Log.d("Package", "Package Name : "+ componentInfo.getPackageName());
if(componentInfo.getPackageName().equals("your application package name")){
Intent intent = new Intent("giveyourappname");
//add data you wnat to pass in intent
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}
}catch(Throwable e){
e.printStackTrace();
}
In my app, whenever I receive a push notification, I will perform a check if my mainActivity is visible to the user to do something...
I have a static boolean value that is set true inside onResume of mainActivity, and false inside it's onPause.
What should I do inside the onMessage
#Override
protected void onMessage(Context context, Intent intent)
{
if(mainActivity == visible)
//do something inside mainactivity.. change text inside edittext
else
//do something else
}
any insights ?
I'm not a fan of keeping static references to activities. I think they're a can of worms ready to explode on you. So you'll suggest an alternative to #TeRRo answer:
on your global BroadcastReceiver onMessage you'll send a LocalBroadcast that your activity will be listening to. Like this:
private static final String ACTION_PUSH_RECEIVED = "com.myapp.mypackage.action.pushReceived";
public static final IntentFilter BROADCAST_INTENT_FILTER = new IntentFilter(ACTION_PUSH_RECEIVED);
#Override
protected void onMessage(Context context, Intent intent) {
Intent i = new Intent(ACTION_PUSH_RECEIVED);
i.putExtra( ... add any extra data you want... )
LocalBroadcastManager.getInstance(context).sendBroadcast(i);
}
and now we make the activity listen to it:
#Override
protected void onResume() {
super.onResume();
LocalBroadcastManager.getInstance(context)
.registerReceiver(mBroadcastReceiver, BroadcastReceiverClass.BROADCAST_INTENT_FILTER);
}
#Override
protected void onPause() {
LocalBroadcastManager.getInstance(context)
.unregisterReceiver(mBroadcastReceiver);
super.onPause();
}
private BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver(){
#Override
public void onReceive(Context context, Intent intent){
// read any data you might need from intent and do your action here
}
}
To avoid this, you should manage activities references. Add the name of the application in the manifest file:
<application
android:name=".MyApp"
....
</application>
Your application class :
public class MyApp extends Application {
public void onCreate() {
super.onCreate();
}
private Activity mCurrentActivity = null;
public Activity getCurrentActivity(){
return mCurrentActivity;
}
public void setCurrentActivity(Activity mCurrentActivity){
this.mCurrentActivity = mCurrentActivity;
}
}
Create a new Activity :
public class MyBaseActivity extends Activity {
protected MyApp mMyApp;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mMyApp = (MyApp)this.getApplicationContext();
}
protected void onResume() {
super.onResume();
mMyApp.setCurrentActivity(this);
}
protected void onPause() {
clearReferences();
super.onPause();
}
protected void onDestroy() {
clearReferences();
super.onDestroy();
}
private void clearReferences(){
Activity currActivity = mMyApp.getCurrentActivity();
if (currActivity != null && currActivity.equals(this))
mMyApp.setCurrentActivity(null);
}
}
So, now instead of extending Activity class for your activities, just extend MyBaseActivity. Now, you can get your current activity from application or Activity context like that :
Activity currentActivity = ((MyApp)context.getApplicationContext()).getCurrentActivity();
Or why don't you use the Local broadcasts when you receive the push notification, and receive it in your activity, and do respective changes or actions.
And if they are UI intensive tasks, bind your activity to a service, and receive the push notification and perform the action in this service and use the result in the activity.
Well, I have a service, I have an Activity. They communicate via messages (It must communicate with messages so don't tell me about Intents or other things, please).
I receive a Bundle from the Service, all ok.
Now with the Bundle i've received I want to do something. I want to call a method from "SomeClass", but I can't, because I'm inside of "IncomingHandler" class.
What's the best way to call SomeClass from inside IncomingHandler?
Thanks in advance
class SomeClass implements ServiceConnection {
class IncomingHandler extends Handler {
#Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MyService.MS_GET_SOMETHING:
Bundle received=msg.getData();
...
If you really want the activity to be calling methods on the service, its time to learn about AIDL, which allows an Activity to make function calls on a bound service via an RPC mechanism. Documentation found here.
I have implemented the feature (Service calls method in activity) like this:
Service sends a broadcast-message.
Activity has a local nested broadcastreceiver that can call a method in the parent activity.
public class MainActivity extends Activity {
private BroadcastReceiver myReceiver = null;
class _RemoteTimeTrackerReceiver extends BroadcastReceiver {
#Override
public void onReceive (Context context, Intent intent) {
// call method in activity
reloadGui();
}
}
#Override
public void onResume() {
super.onResume();
if (myReceiver == null)
{
myReceiver = new _RemoteTimeTrackerReceiver();
IntentFilter filter = new IntentFilter(Global.REFRESH_GUI);
registerReceiver(myReceiver, filter);
}
reloadGui();
}
#Override
public void onPause() {
if (myReceiver != null)
{
unregisterReceiver(myReceiver);
myReceiver = null;
}
super.onPause();
}
void reloadGui() {}
I have an Android application which uses C2DM services (aka push).
I have a separate class which implements the registration process and which receives the data (and extends BroadcastReceiver).
I want to communicate this data to the activity which currently is in the foreground. The activity currently in the foreground may differ depending on user action.
What's the best way to communicate in between the receiver and the current activity?
Thanks.
I solved this problem by sending out a new broadcast from the C2DMReceiver class, which looked something like this.
The C2DMReceiver class:
public class C2DMReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals("com.google.android.c2dm.intent.REGISTRATION")) {
handleRegistration(context, intent);
} else if (intent.getAction().equals("com.google.android.c2dm.intent.RECEIVE")) {
handleMessage(context, intent);
}
}
private void handleRegistration(Context context, Intent intent) {
// handle registration
}
private void handleMessage(Context context, Intent intent) {
Intent i = new Intent("push");
i.putExtras(intent);
// context.sendOrderedBroadcast(i, null);
context.sendBroadcast(i);
}
}
Another class I called PushReceiver. This is the class that will extend BroadcastReceiver and receive the broadcast sent by C2DMReceiver.
public class PushReceiver extends BroadcastReceiver {
public PushReceiver() {
}
#Override
public void onReceive(Context context, Intent intent) {
// do stuff
abortBroadcast();
}
public static class PushFilter extends IntentFilter {
private static final int DEFAULT_PUSH_PRIORITY = 1;
public PushFilter() {
this(DEFAULT_PUSH_PRIORITY);
}
public PushFilter(int priority) {
super("push");
setPriority(priority);
}
}
}
And the activity class, in this case called MyActivity. This should work well if you are using a base activity class that all other activities extend. That way every activity registers the receiver. By doing the register/unregister in onResume/onPause, you should be able to guarantee that only the current activity receives the broadcast. If not, you can send an ordered broadcast from C2DMReceiver and use priority in the PushFilter.
public class MyActivity extends Activity {
private PushReceiver pushReceiver;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// your onCreate method
pushReceiver = new PushReceiver();
}
public void onResume() {
super.onResume();
// your onResume method
registerReceiver(pushReceiver, new PushReceiver.PushFilter());
}
public void onPause() {
super.onPause();
// your onPause method
unregisterReceiver(pushReceiver);
}
}
In my case, I wrote the PushReceiver constructor to take a View and then "did stuff" with the view in the onReceive method. Without knowing more about what your trying to do, I can't elaborate on this, but hopefully this can provide a decent template to work from.