How can i notify and execute instantly a method from the MainActivity class when a method from a non-activity class has finished?
MainActivity class:
public class MainActivity extends AppCompatActivity {
private ExpandableListViewAdapter mExpandableListViewAdapter;
PreselectionAplicationUseCases preselectionAplicationUseCases;
public void Preselection(){
if(preselectionAplicationUseCases.isMsg100PreselectionAplication()) {
mExpandableListViewAdapter.setSelectedChild(-1);
}
}
Non-activity class:
public class MSG0100 implements PreselectionAplicationUseCases {
msg100PreselectionAplication=true;
}
public boolean isMsg100PreselectionAplication() {
return msg100PreselectionAplication;
}
public void setMsg100PreselectionAplication(boolean msg100PreselectionAplication) {
this.msg100PreselectionAplication = msg100PreselectionAplication;
}
And the interface:
public interface PreselectionAplicationUseCases {
boolean isMsg100PreselectionAplication();
void setMsg100PreselectionAplication(boolean msg100PreselectionAplication);
}
So how can I execute the method Preselection automatically when this happens
msg100PreselectionAplication=true; in the non-activity class.
I was thinking that i can use a thread with wait and notify, but i think that can give some problems to the UI thread.
Couldn't you just use Observer pattern?
public class MSG0100 implements PreselectionAplicationUseCases {
private OnMsg100PreselectionChanged listener = null;
public void setOnMsgPreselectionChanged(OnMsg100PreselectionChanged listener) {
this.listener = listener;
}
public void setMsg100PreselectionAplication(boolean msg100PreselectionAplication) {
if(listener != null) {
listener.onPreselectionChanged(msg100PreselectionAplication);
}
}
}
interface OnMsg100PreselectionChanged {
void onPreselectionChanged(boolean isChanged);
}
public class MainActivity extends AppCompatActivity {
private ExpandableListViewAdapter mExpandableListViewAdapter;
PreselectionAplicationUseCases preselectionAplicationUseCases;
public void Preselection(){
preselectionApplicationUseCases.setOnMsgPreselectionChanged(new OnMsg100PreselectionChanged {
#Override
void onPreselectionChanged(boolean isChanged) {
//do something with changed boolean
}
});
}
}
You can create inteface like this and implement it in your activity class:
public interface OnMethodFinishedListener {
void onMethodFinish();
}
then make method call in your non-activity class:
public class MSG0100 implements PreselectionAplicationUseCases {
msg100PreselectionAplication=true;
}
private OnMethodFinishedListener mListener
public MSG0100 (OnMethodFinishedListener listner){
mListener = listener;
}
public boolean isMsg100PreselectionAplication() {
return msg100PreselectionAplication;
}
public void setMsg100PreselectionAplication(boolean msg100PreselectionAplication) {
this.msg100PreselectionAplication = msg100PreselectionAplication;
//here for example. or anywhere you need
mListener.onMethodFinish
}
And that is it - your activity will get call in overrided onMethodFinished method
This could be done also using while
while(msg100PreselectionAplication=true){
//do something to notify after that we set preselection again to false
msg100PreselectionAplication=false;
}
Related
I've been trying to find a way to create a listener for a boolean on an android code reader. Essentially what I want to happen is, when it stops reading, perform action. So far I've based it off of this example, and have this:
Class:
public class scanStatusListener {
ScanManager scanManager;
private boolean scanStatus = scanManager.isReading(); //this returns if the reader is scanning or not
private ChangeListener listener;
public void setListener(ChangeListener listener) {
this.listener = listener;
}
public interface ChangeListener {
void onChange();
}
}
Activity:
public class ScanHook extends Service implements ScanManager.DataListener, scanStatusListener.ChangeListener{
private ScanManager _scanManager;
#Override
public void onCreate() {
super.onCreate();
_scanManager = ScanManager.createScanManager(getApplicationContext());
scanStatusListener ss = new scanStatusListener();
ss.setListener(new scanStatusListener.ChangeListener() {
public void onChange() {
//perform action
}
});
}
The issue I am getting is:
private boolean scanStatus = scanManager.isReading();
is getting an error saying that I cannot invoke on a null object reference.
I also tried using the LiveData suggestion:
MutableLiveData<Boolean> listen_bool=new MutableLiveData<>();
listen_bool.observe((LifecycleOwner) this, new Observer<Boolean>() {
#Override
public void onChanged(Boolean aBoolean) {
//perform action
}
});
listen_bool.setValue(_scanManager.isReading());
however I am getting an error saying I cannot cast to androidx.lifecycle.LifecycleOwner
Any suggestions?
MainActivity execute external asynctask class
Here my code
public class MainActivity extends AppCompatActivity implements View.OnClickListener
...
public void onFirstBtnClick()
{
AysncClass ac = new AyncClass();
ac.execute();
}
and external asynctask
public class AysncClass extends AsyncTask<String, String, Integer>
#Override
protected Integer doInBackground(String... strings) {
Method1(strings[0], Integer.parseInt(strings[1]));
return null;
}
public Method1(Strins s, int i)
{
onProgressUpdate("first start");
publishProgress();
// do more work
onProgressUpdate("second start");
publishProgress();
}
public void Method2()
{
onProgressUpdate("Method2 here");
publishProgress();
}
...
#Override
protected void onProgressUpdate(final String... values) {
super.onProgressUpdate(values);
// what can i do here?
}
}
I use runOnUiThread like this in onProgressUpdate
((MainActivity)context).runOnUiThread(new Runnable()
{
#Override
public void run()
{
((MainActivity)context).tvRead.append(values[0]);
}
});*
but It occur 'java.lang.ArrayIndexOutOfBoundsException: length=0; index=0' even though values[0] is not null.
Also I use interface
this.context.WriteText(values[0]);
It occur same error
And I do this...
((MainActivity)context).tvRead.append(values[0]);
It occur 'java.lang.RuntimeException: An error occured while executing doInBackground()' and 'CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.'
...How can I resolve?
Do not call onProgressUpdate(). Instead just call publishProgress("The String").
By calling publishProgress without a parameter you will have no values in onProgressUpdate. That's why you get an IndexOutOfBondException.
Don't call onProgressUpdate on your own.
Call publishProgress("My Message");
In onProgressUpdate, don't use runOnUIThread.
OnProgressUpdate runs on the Ui thread only.
Instead of this
onProgressUpdate("Method2 here");
publishProgress();
Do this
publishProgress("Method2 here");
On ProgressUpdate will be in UIThread, no need again specify in UI thread. From DoInbackGround you have to make call publishProgress method for invoking OnProgressUpdate.
Use an interface as communicator between your Activity and AsyncTask
Create Interface
interface MyInterface {
void callActivityUi(String progress); // use float maybe
}
Initialize AsyncTask like this:
AysncClass as = new AysncClass(new MyInterface() {
#Override
void callActivityUi (String progress) {
// you will receive data here
}
});
Create a constructor in your AysncClass
private MyInterface myInterface;
public AysncClass (MyInterface myInterface) {
this.myInterface = myInterface;
}
Call Activity in onProgressUpdate(String... values)
myInterface.callActivityUi(values[0]);
Based on your code, you can use an interface to post the progress to the activity. I modified your code like this:
AsyncTask class
public class AysncClass extends AsyncTask<String, String, Integer> {
public interface SomeListener {
public void onSomething(Object mObject);
}
private SomeListener sl;
public AysncClass(SomeListener sl) {
this.sl = sl;
}
#Override
protected Integer doInBackground(String... strings) {
Method1(strings[0], Integer.parseInt(strings[1]));
return null;
}
public Method1(Strins s, int i) {
onProgressUpdate("first start");
publishProgress();
// do more work
onProgressUpdate("second start");
publishProgress();
}
public void Method2() {
onProgressUpdate("Method2 here");
publishProgress();
}
...
#Override
protected void onProgressUpdate(final String... values) {
super.onProgressUpdate(values);
// what can i do here?
sl.onSomething(mObject);
}
}
MainActivity class
public class MainActivity extends AppCompatActivity implements View.OnClickListener,
AysncClass.SomeListener {
...
public void onFirstBtnClick() {
AysncClass ac = new AyncClass(this);
ac.execute();
}
#Override
public void onSomething(Object mObject) {
//Do your UI work here
}
}
I try a Toast Message interface. If app not connection internet, I want show a Toast Message and I'm wanting java interfaces.
This is MotherActivity.java. This file implement ToastMessagges.ToastMessaggeCallback
public class MotherActivity extends ActionBarActivity implements ToastMessagges.ToastMessaggeCallback {
ToastMessagges toastMessagges;
#Override
protected void onStart() {
super.onStart();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mother);
toastMessagges = new ToastMessagges();
AppStarter();
}
private void AppStarter(){
boolean checkinternet = InternetControl.checkInternetConnection( getApplicationContext() );
if( checkinternet ) {
toastMessagges.show_toast_messagge();
}
else {
}
}
#Override
public void LongToastMessagge() {
Toast.makeText(getApplicationContext(), "Hello World", Toast.LENGTH_LONG).show();
}
}
This is my ToastMessagges.java file.
public class ToastMessagges {
ToastMessaggeCallback toastMessaggeCallback;
public void show_toast_messagge(){
toastMessaggeCallback.LongToastMessagge();
}
public static interface ToastMessaggeCallback {
public void LongToastMessagge();
}
}
When the start this app. I get NullPointerException error.
Caused by: java.lang.NullPointerException
at com.medyasef.bulenttirasnewapp.bulenttiras.functions.ToastMessagges.show_toast_messagge(ToastMessagges.java:22)
at com.medyasef.bulenttirasnewapp.bulenttiras.MotherActivity.AppStarter(MotherActivity.java:36)
at com.medyasef.bulenttirasnewapp.bulenttiras.MotherActivity.onCreate(MotherActivity.java:29)
ToastMessagges.java:22
toastMessaggeCallback.LongToastMessagge();
Sorry bad english.
Please help.
Thank you.
You haven't initialized you ToastMessaggeCallback toastMessaggeCallback.
To do this, write
ToastMessaggeCallback toastMessaggeCallback = new ToastMessaggeCallback(){
public void LongToastMessagge(){
// add some toasting code here
}
};
This will make an object implementing your interface (called "anonymous class"). Of course, your ToastMessaggeCallback should do something in the method LongToastMessagge, so add the desired code there.
I will recommend you to create a Util class instead of Interface. I'm here giving you an example of Util class.
public class Util {
public static void showToast(Context context, String text) {
Toast.makeText(context, text, Toast.LENGTH_SHORT).show();
}
}
Then call the showToast() method from your activity as follows...
Util.showToast(YourActivity.this, "text");
Update:
Declare your Interface as a individual, not inside a class as below...
public interface ToastMessaggeCallback {
public void showLongToastMessagge(String text);
}
Then implement the Interface as follows...
public class MotherActivity extends ActionBarActivity implements ToastMessaggeCallback {
#Override
protected void onStart() {
super.onStart();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mother);
AppStarter();
}
private void AppStarter(){
boolean checkinternet = InternetControl.checkInternetConnection( getApplicationContext() );
if( checkinternet ) {
showLongToastMessagge("Hello World");
}
else {
}
}
#Override
public void showLongToastMessagge(String text) {
Toast.makeText(getApplicationContext(), text, Toast.LENGTH_LONG).show();
}
}
Your ToastMessagges class needs to provide a method to register the callback. Then, your Activity needs to call this method to register itself as the callback, right after you construct the ToastMessages object.
I need to connect to facebook so I use a Tread when using the network. but I have a problem:
Thread t = new Thread(new Runnable() {
#Override
public void run() {
FacebookConnectTask task = new FacebookConnectTask("facebookId", "token", "email", facebookGender,0, 0);
task.setOnPreExecuteListener(this);
task.setOnDoneListener(this);
task.execute();
}
});
t.start();
}
I cant do
task.setOnPreExecuteListener(this);
task.setOnDoneListener(this);
eclipse gives me this error: "The method setOnDoneListener(Task.OnDoneListener) in the type Task is not applicable for the arguments (new Runnable(){})"
How can i fix this?
Thanks!
You've changed context's by being in a Thread your in an Annoyomous class, this is now your annonomous class and not the outer class.
Try this (pun intended):
task.setOnPreExecuteListener(YourOuterClass.this);
task.setOnDoneListener(YourOuterClass.this);
i.e.
public class YourClass implements OnDoneListener {
public doFacebook(){
new Thread(new Runnable(){
#Override
public void run(){
task.setOnDoneListener(YourClass.this);
}
}.start();
}
#Override
public void onDone(){
}
}
or alternatively pull your Threaded class out:
public class DoSomething implements Runnable {
private final OnDoneListener listener;
public DoSomething(OnDoneListener listener){
this.listener = listener;
}
#Override
public void run(){
FacebookConnectTask task = ... ;
task.setOnDoneListener(listener);
}
}
public class YourActivity extends Activity implements OnDoneListener {
public void onCreate(Bundle b){
new Thread(new DoSomething(this)).start();
}
#Override
public void onDone(){
// Tada
}
}
A further step if you wanted to be cooler is create your own interface and keep all the Facebook stuff in the runnable class:
public class DoSomething implements Runnable, OnDoneListener {
public interface OnFacebookFinished {
void onFacebookFinished();
}
private final OnFacebookFinished listener;
public DoSomething(OnFacebookFinished listener){
this.listener = listener;
}
#Override
public void run(){
FacebookConnectTask task = ... ;
task.setOnDoneListener(this);
}
#Override
public void onDone(){
if(listener != null){
listener.onFacebookFinished();
}
}
}
public class YourActivity extends Activity implements OnFacebookFinished {
#Override
public void onCreate(Bundle b){
new Thread(new DoSomething(this)).start();
}
#Override
public void onFacebookFinished(){
// Tada
}
}
public interface DownloadListener {
public void onDownloaded();
}
public class DownloadManager {
private static DownloadManager instance;
private DownloadListener mDownloadListener;
public static synchronized DownloadManager getInstance(){
if(instance == null)
instance = new DownloadManager();
return instance;
}
private DownloadManager() {
myHandler.sendEmptyMessageDelayed(29, 3 * 1000);
}
public void registerDownloadListener(DownloadListener downloadListener) {
mDownloadListener = downloadListener;
}
Handler myHandler = new Handler(new Handler.Callback() {
#Override
public boolean handleMessage(Message msg) {
if (msg.what == 29) {
mDownloadListener.onDownloaded();
return true;
}
return false;
}
});
}
public class I implements DownloadListener {
public I() {
DownloadManager.getInstance().registerDownloadListener(this);
}
#Override
public void onDownloaded() {
Log.e("TAG", "I onDownloaded");
}
}
public class You implements DownloadListener {
public You() {
DownloadManager.getInstance().registerDownloadListener(this);
}
#Override
public void onDownloaded() {
Log.e("TAG", "You onDownloaded");
}
}
public class PATTERNSActivity extends Activity implements DownloadListener {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
new I();
new You();
DownloadManager.getInstance().registerDownloadListener(this);
}
#Override
public void onDownloaded() {
Log.e("TAG","PATTERNSActivity onDownloaded");
}
}
I am expecting to get:
I onDownloaded
You onDownloaded
PATTERNSActivity onDownloaded
But I am getting only:
PATTERNSActivity onDownloaded
What could it be the problem?
You keep registered downloaders in a single instance property:
// Last call's downloadListener wins.
public void registerDownloadListener(DownloadListener downloadListener) {
mDownloadListener = downloadListener;
}
The last one registered is the activity's:
new I(); // First set singleton's property to an instance of I...
new You(); // ...then to an instance of You...
// ...then to the current instance.
DownloadManager.getInstance().registerDownloadListener(this);
Edit based on your comment.
public void registerDownloadListener(DownloadListener downloadListener) {
mDownloadListeners.add(downloadListener);
}
...
public boolean handleMessage(Message msg) {
if (msg.what != 29) {
return false;
}
for (DownloadListener listener : mDownloadListeners) {
listener.onDownloaded();
}
return true;
}
In your code, this gets executed by calling mDownloadListener.onDownloaded(); in the DownloadManager class.
#Override
public void onDownloaded() {
Log.e("TAG","PATTERNSActivity onDownloaded");
}
In don't see why the onDownloaded methods of the I and YOU class should be executed, they're never called. Only the OnDownloaded method of your Listener is called.
For starters, I think you are not using a list. You just override the value so you will always get the last one:
public void registerDownloadListener(DownloadListener downloadListener) {
mDownloadListener = downloadListener;
}