I am having difficulty in figuring out what is wrong with my code, My code runs when the onclick listener is not yet implemented but once I implement the onclick listener it crashes.
public class menu extends AppCompatActivity implements View.OnClickListener {
private CardView assess, profile, chatbot, breathing;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.menu);
assess = (CardView) findViewById(R.id.assess);
profile = (CardView) findViewById(R.id.profile);
chatbot = (CardView) findViewById(R.id.chatbot);
breathing = (CardView) findViewById(R.id.breathing);
// assess.setOnClickListener(this);
// profile.setOnClickListener(this);
// chatbot.setOnClickListener(this);
// breathing.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// Intent i;
//
// switch (v.getId()){
//
//
// case R.id.assess :
// i = new Intent(this,depression_assessment.class);
// startActivity(i);
// break;
}
}
//}
When I tried debugging the codes, these lines are the cause of the crash.
// assess.setOnClickListener(this);
// profile.setOnClickListener(this);
// chatbot.setOnClickListener(this);
// breathing.setOnClickListener(this);
It is where the problem is starting because the code works even though the onclick is blank. When I checked the logs it shows this error
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.example.thesis/com.example.thesis.menu}:
java.lang.NullPointerException: Attempt to invoke virtual method 'void
androidx.cardview.widget.CardView.setOnClickListener(android.view.View$OnClickListener)'
on a null object reference
You haven't shown enough code, but this could be due to serveral reasons:
This line of code breathing = (CardView) findViewById(R.id.breathing); will look for a view with id breathing inside your activity's layout, and according to the error it is null, which means it did not find it within the same activity's layout, so make sure your cardView is in this activity's layout. Another possible reason is that you might have duplicate Ids in your xml files, in this case,find the duplicate and rename the Ids.
Related
To illustrate what I mean with this, it is similar to WhatsApp, where various options are displayed in the toolbar when a chat is selected.
I have a similar layout, so a MainActivity with Fragments containing RecyclerViews. Now when an item in a RecyclerView is selected I would like to get a similar behaviour as in WhatsApp. The RecyclerViews have an Adapter that implements an OnClickListener.
However, from this Adapter I do not seem to have access to Views from the MainActivity. I tried the following (inside the OnClick method in the Adapter), but it did not work since the view could not be found.
View view = getActivity().findViewById(R.id.toolbar_main_activity);
if( view instanceof Toolbar) {
Toolbar toolbar = (Toolbar) view;
toolbar.setTitle("TestTitle");
}
Does anyone know how to get the intended behavior or have a reference to a tutorial?
UPDATE: for who is also stuck with this and this is still quite confusing, here is how I solved it in my own words
My Fragment contains the Interface by adding the following code to it;
OnItemsSelected mCallBack;
public interface OnItemsSelected {
void onToolbarOptions(String title);
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
mCallback = (OnItemsSelected) getActivity();
}
Also I passed 'mCallback' to the adapter like this;
MyAdapter adapter = new MyAdapter(myList, mCallback);
The RecyclerView adapter implements OnClickListener. In the OnClick method I called; 'mCallBack.onToolbarOptions("someTitle");'. And finally I made my MainActivity implement the method; 'implements myFragment.onItemsSelected' and I added the following code to it also;
#Override
public void onToolbarOptions(String title) {
toolbar.setTitle(title);
}
With this, only the title is changed, but from this it is quite easy to make other changes to the toolbar, such as changing the menu items.
Inside your Fragment you make an Interface and a global variable like this:
OnItemsSelected mCallBack;
public interface OnItemsSelected {
public void onToolbarOptions();
}
Then when in your RecyclerView items are selected or clicked you call:
mCallBack.onToolbarOptions();
In your Activity implement the Interface like this plus the method onToolbarOptions():
public static class YourActivityName extends AppCompatActivity
implements YourFragmentName.OnItemsSelected {
public void onToolbarOptions(){
// CHANGE YOUR TOOLBAR HERE
}
//.....OTHER STUFFS IN YOUR ACTIVITY
}
Im new to android and very new to android plot. Can you point me to an example that uses FixedSizeEditableXYSeries?
My goal is to create a streaming plot that shows the latest sensor readings in an android app.
Thanks
===================Update - following discussion with #Nick====================
public class MainActivity extends AppCompatActivity {
// Create the redrawer so that the plot is updated
private Redrawer redrawer;
// create the message receiver - data is received via broadcasts
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
// Get extra data included in the Intent
String message = intent.getStringExtra("CurrentHR");
Log.d("ReceivedHR ",message);
// Now put the new data point at the end of the FixedSizeEditableXYSeries, move all data points by 1.
for (int index=0;index<9;index++){
if(index<9){
hrHistory.setY(hrHistory.getY(index+1),index);
}else{
hrHistory.setY(Float.parseFloat(message),9);
}
}
}
};
// create a few references
private XYPlot xyPlot;
private FixedSizeEditableXYSeries hrHistory;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_heart_rate);
// Now find the plot views
xyPlot = (XYPlot)findViewById(R.id.xyPlot);
// Declare the local broadcast manager
LocalBroadcastManager.getInstance(this).registerReceiver(
mMessageReceiver, new IntentFilter("hrUpdate"));
// now put in some data
hrHistory = new FixedSizeEditableXYSeries("HR",10);
xyPlot.addSeries(hrHistory, new LineAndPointFormatter(Color.GREEN,Color.RED,null,null));
xyPlot.setRangeBoundaries(40, 120, BoundaryMode.FIXED);
xyPlot.setDomainBoundaries(0, 20, BoundaryMode.FIXED);
}
#Override
protected void onResume(){
super.onResume();
// set a redraw rate of 1hz and start immediately:
redrawer = new Redrawer(xyPlot, 1, true);
}
}
This gives me a nice graph but no line. It doesnt look like the plot is being updates as new data is filling the FixedSizeEditableXYSeries.
If you want scrolling behavior then FixedSizeEditableXYSeries would be the wrong choice; as your data scrolls you're essentially enqueueing the newest value and dequeuing the oldest value; a linked list type structure would be a better choice.
You can either implement XYSeries and back it with any suitable data structure you prefer, or you can use SimpleXYSeries, which already supports queue operations a la removeFirst() and addLast(...). There's a great example of of a dynamic scrolling plot in the demo app: OrientationSensorExampleActivity. Lines 235-245 show the specific actions mentioned above.
Here's a failing test:
#RunWith(RobolectricTestRunner.class)
public class FailTest {
#Test
public void heightAndWidth_shouldNotBeZero() {
TestActivity testActivity = Robolectric.buildActivity(TestActivity.class).create().resume().visible().get();
View contentView = testActivity.findViewById(69);
Assertions.assertThat(contentView.getWidth()).isNotZero();
Assertions.assertThat(contentView.getHeight()).isNotZero();
}
private static class TestActivity extends Activity {
#Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout contentView = new LinearLayout(this);
contentView.setId(69);
contentView.setLayoutParams(new LayoutParams(666, 666));
setContentView(contentView);
}
}
}
As you can see, I'm calling the visible() method on the ActivityController and driving the Activity lifecycle the correct way. Quoting the documentation:
Wait, What's This visible() Nonsense?
Turns out that in a real Android app, the view hierarchy of an
Activity is not attached to the Window until sometime after onCreate()
is called. Until this happens, the Activity's views do not report as
visible. This means you can't click on them (amongst other unexpected
behavior). The Activity's hierarchy is attached to the Window on a
device or emulator after onPostResume() on the Activity. Rather than
make assumptions about when the visibility should be updated,
Robolectric puts the power in the developer's hands when writing
tests.
So when do you call it? Whenever you're interacting with the views
inside the Activity. Methods like Robolectric.clickOn() require that
the view is visible and properly attached in order to function. You
should call visible() after create().
It seems as though I'm doing all I need to do. So why am I getting no height/width?
There is no layout pass in Robolectric, hence the view dimensions are always zero.
https://github.com/robolectric/robolectric/issues/819
I have a main Activity (OceanintelligenceActivity). In this activity I register the device for push notifications and also I registered a receiver that shows a Dialog and starts the proper Activity depending on the info sent from my server. This is the code I'm using to register the device and the receiver :
protected void gcmRegistration(){
PMApplication thisApp = PMApplication.getInstance();
AppDelegate delegate = thisApp.getAppDelegate();
final Context context = this;
// Make sure the device has the proper dependencies.
GCMRegistrar.checkDevice(this);
// Make sure the manifest was properly set - comment out this line
// while developing the app, then uncomment it when it's ready.
GCMRegistrar.checkManifest(this);
// Let's declare our receiver
registerReceiver(mHandleMessageReceiver,new IntentFilter(DISPLAY_MESSAGE_ACTION));
final String regId = GCMRegistrar.getRegistrationId(this);
if (regId.equals("")) {
Log.d("", "Lets register for Push");
GCMRegistrar.register(this, SENDER_ID);
}else {
if(GCMRegistrar.isRegisteredOnServer(this)) {
// Skips registration.
String apnsToken = delegate.sso.getAPNSToken();
if(!apnsToken.equals(regId)){
Log.d("", "The Device RegId has changed on GCM Servers");
// We should let our servers know about this
ServerUtilities.update(regId, context);
}
} else {
Log.d("","Is not register on PM Server");
// Try to register again, but not in the UI thread.
// It's also necessary to cancel the thread onDestroy(),
// hence the use of AsyncTask instead of a raw thread.
mRegisterTask = new AsyncTask<Void, Void, Void>() {
#Override
protected Void doInBackground(Void... params) {
boolean registered = ServerUtilities.register(context, regId);
// At this point all attempts to register with the app
// server failed, so we need to unregister the device
// from GCM - the app will try to register again when
// it is restarted. Note that GCM will send an
// unregistered callback upon completion, but
// GCMIntentService.onUnregistered() will ignore it.
if (!registered) {
GCMRegistrar.unregister(context);
}
return null;
}
#Override
protected void onPostExecute(Void result) {
mRegisterTask = null;
}
};
mRegisterTask.execute(null, null, null);
}
}
}
This is how I set the receiver:
private final BroadcastReceiver mHandleMessageReceiver =
new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String newMessage = intent.getExtras().getString(EXTRA_MESSAGE);
Log.d("","BroadcastReceiver onReceive");
notificationIntent = GCMIntentService.getNotificationIntent(context);
new AlertDialog.Builder(context)
.setMessage(newMessage+". Would you like to see it right now?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// Show update
startActivity(notificationIntent);
}
})
.setNegativeButton("No", null).show();
}
};
GCMIntentService.getNotificationIntent(context). This line returns the the Intent with the Activity I want to start.
Whenever there is a notification onReceive gets called but the Dialog only shows if I am on the main activity. So if the app is on a different activity, onReceive still gets called but the dialog doesn't show and therefore I can't start the proper activity.
How can I display a dialog on Currently visible activity on BroadcastReceiver?
Playing around with this one and searching on google I came across a solution. It is not the best one but it works. I still can't believe there is not an easy way to get the current context in Android. So this is what I did to manage to show the Dialog regardless of what the current activity is : I have a public static property of type Context on my singleton class(AppDelegate) and on each activity I override the onResume method and set the Context to the current activity like this AppDelegate.CURRENT_CONTEXT = this. Then on my dialog : AlertDialog.Builder(AppDelegate.CURRENT_CONTEXT).....
I have an update database operation, that has an activity, which keeps updating the percentage and it runs inside an AsyncTask.
Inside doInBackground() I call the controller that updates the database and keep updating the percentage on the activity, however, if I press home button or back button, the operation is cancelled. What u suggest me to do?
I was trying to start a Service inside doInBackground() so it would run in background, but it looks like its not working.
My code looks like this:
public class UpdateDatabaseAsyncTask extends AsyncTask<Void, Integer, Integer>
{
#Override
public void onPreExecute()
{
mCustomProgressBar.startAnimation();
}
#Override
public Integer doInBackground(Void... params)
{
return mController.updateDatabase();
}
#Override
public void onPostExecute(Integer result)
{
mCustomProgressBar.stopAnimation();
// finish the activity
}
#Override
public void onProgressUpdate(Integer... value)
{
updatePercentageValue(value[0]);
}
public void callPublishProgress(Integer value)
{
publishProgress(value);
}
}
And inside the controller I call the method callPublishProgress(value) passing the current percentage value, so it will publishProgress(value) in the UI.
I was debugging, and I pressed the home/back button, and it just stopped running the worker thread.
Another solution I tried, was starting a Service to run in background no matter the user press home/back button or not, so I thought, and the Service would make a call to the controller method that does the work, and it would call the callPublishProgress(value) to update the percentage value on the UI anyways.
However, what was happening is, the code reach doInBackground() and start the service, but it goes to onPostExecute() immediately, it just didn't wait the service to finish(of course!). So it gives a NullPointerException. I thought of making a loop inside doInBackground() with a flag set in the Service, so it would leave this loop while the service hasn't been finished (I was using an IntentService), but it didn't work anyways.
I thought of using a Timer too. But I don't know.
I was reading the articles in documentation about Threads, etc. And it suggests using AsyncTask, just as I was trying to do. It also talks about runOnUiThread(Runnable).
Anyways what I need is to make an operation in background(probably using an IntentService), so no matter if the user press the home button, it will keep running, but it must update the percentage on the UI, and when the user leave the screen and back to it, it shows the current percentage value updated in the screen.
What is the best solution for my case?
Thanks.
public class MyServce extends Service{
public static final String BROADCAST_ACTION = "com.myapp";
Intent intent;
private final Handler handler = new Handler();
#Override
public void onCreate()
{
super.onCreate();
intent = new Intent(BROADCAST_ACTION);
}
#Override
public void onStart(Intent intent, int startId) {
handler.removeCallbacks(sendUpdatesToUI);
handler.postDelayed(sendUpdatesToUI, 1000); // 1 second
}
private Runnable sendUpdatesToUI = new Runnable() {
public void run() {
DoYourWorking();
handler.postDelayed(this, 1000); // 1 seconds
}
private void DoYourWorking() {
........
........
intent.putExtra("key", progress);
sendBroadcast(intent);
}
};
#Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
return null;
}
#Override
public void onDestroy() {
super.onDestroy();
handler.removeCallbacks(sendUpdatesToUI);
}
Now in your Activity register broadcast to service
private BroadcastReceiver brodcast = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
//intent.getWhatever
// update your progress
//progressbar.setProgress
}
register broadcast
registerReceiver(brodcast, new IntentFilter(MyService.BROADCAST_ACTION));
This worked for me. I started a background service on a thread that just fetches the values and updates an object in a singleton.
In the view controller, I start a timer that keeps updating the view by fetching data from the object in singleton.
I had a little problem understanding your entire question text, so I'm not sure if you have tried this. But this is what worked. Also, the service was started with START_STICKY
Use an IntentService (which is a Service on a thread of its own), and Handler to pass the data back to the Activity.