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Logs in Android Studio

I am a newbie of Android Studio.
I have a problem with display the logs in my app.
For example:
String timeStamp = new
SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime());
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cycle);
TextView textView = (TextView) findViewById(R.id.cykleoncreate);
Log.d("[ " + timeStamp + "]", "[onCreate]");
I only want to display this log in my app. How can I do it?

you can display the logs by Toast or set in textView
Toast.makeText(getApplicationContext(),timeStamp,Toast.LENGTH_SHORT).show();
or
textView.setText(timeStamp);

What you have done is write but you can get confused as in where's the log, Log has tag and message, Tags are usually Activity or fragment name so that its easier for one to locate from where did a particular error or message came from, and you can include anything in the message part of it.
we have different types of logs this can be found here
You will find a logcat button on bottom side left side of android studio from there you can select depending on which type you want to see? in your case it's debug

Ok, it works well
textView.setText(timeStamp)
But I don't know why it doesn't work, when I want to build my string:
textView.setText(timeStamp + "my string")

Actually Log is not displaying in app , it will display in android studio . For displaying in app , we need to use Toast . your code is working fine you can check it in your android studio , as its shown in image We can display like this Log.d("onCreate", timeStamp); and search using TAG as onCreate.

How to change a photo?

I am trying to change photos in android studio by clicking on my button.
When I put code for changing the photo in my MainActivity.java I keep getting this type of error messages and it says :
Cannot resolve symbol "image"
image.setImageResource(R.drawable.xxx);
I am watching Udemy course for android development and I have done everything same like the professor on that video.
I have tried to restart android studio.
I have tried to make new project.
I have tried to clear invalidate caches and restart.
public void changeImage(View view)
{
ImageView bitcoin = findViewById(R.id.bitcoin);
image.setImageResource(R.drawable.xxx);
}
I hope there is actual error with android studio,because code is clone of the video that I am watching.

You are binding your layout's ImageView in Java file with bitcoin variable and you are trying to set an image on an unknown variable 'image'(maybe it's not defined in the class). So you have to set as below.
ImageView bitcoin = findViewById(R.id.bitcoin);
bitcoin.setImageResource(R.drawable.xxx);

Set Your Code Like this
ImageView image = findViewById(R.id.bitcoin);
image.setImageResource(R.drawable.xxx);

change your this line
image.setImageResource(R.drawable.xxx)
to this one:
bitcoin.setImageResource(R.drawable.xxx)

Service Reference for android?

I have a service which I need to access from an android app. The goal is simply to send a number value from a textbox and get a result string back.
I know it is possible to do so in VB using a Service Reference, which I have done. Here is the sample code :
Private Async Sub Button_Click(sender As Object, e As RoutedEventArgs)
Dim service As New ServiceReference2.Service1Client(ServiceReference2.Service1Client.EndpointConfiguration.BasicHttpBinding_IService1)
Try
lblReturn.Text = Await service.GetDataAsync(CInt(txtValueSent.Text))
Catch ex As Exception
lblReturn.Text = ex.Message
If Not ex.InnerException.Message Is Nothing Then
lblReturn.Text = lblReturn.Text + ex.InnerException.Message
End If
End Try
End Sub
After research I can't seem to find any way to have a quick and simple result like it is possible to with Visual Studio using Android Studio
Are there any tools available which work in a similar way ?
If not which process would be recommanded to achieve the same result ?
Are there any usefull links which could help enlighten me?

Android GoogleMap getProjection() not working

This is my first post here, so I hope I'll explain my problem clear enough:
I'm extending the FragmentActivity class to create a HeatMapActivity. In this activity I use a GoogleMap object, which I obtain as follows:
// Try to obtain the map from the SupportMapFragment.
map = ((SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.heatmap)).getMap();
Now, after doing a null-Check etc., I'm adding a TileOverlay in the setUpMap() method, as shown below:
// Configure and add overlay
tileProvider = new HeatMapTileProvider(map);
map.addTileOverlay(new TileOverlayOptions()
.tileProvider(tileProvider));
Ok, so far no problem at all. I implemented the TileProvider interface to provide the tiles for the HeatMap overlay.
I want to use the Projection object for converting latitude/longuitude to and from pixels on the screen. The Projection object should be returned by the getProjection() method of the GoogleMap class.
So now here's the problem: If I use the following code in the HeatMapActivity class, everything is fine:
System.err.println("Test1: " + map.getProjection().fromScreenLocation(new Point(50, 50)));
But if I forward the GoogleMap object to the TileProvider, respectively to the renderer I use, the code is not working anymore:
public byte[] render(int x, int y, int zoom, GoogleMap map) {
...
System.err.println("Test2: " + map);
System.err.println("Test3: " + map.getProjection().fromScreenLocation(new Point(50, 50)));
...
}
I definitely know, that the map parameter is not null (see Test 2), but the code just seems to block when I call getProjection(). There is no error coming up and if I don't use the Projection object, everything else is working fine. I don't have any clue, why I should not be allowed to call getProjection() from another class than the activity...
I am using the ADT bundle for Windows (version x86_64-20130729), Android SDK version from 8 to 17, testing on Android 2.3.5 at the moment. The map is displayed, the needed libraries are included and the permissions are set in the android manifest.
Any ideas? Any help or hints are appreciated.
Seb

The issue here is that getTile (and your render method) are called outside UI thread.
This will cause exception, which you won't see, because it is probably silently handled by the code calling getTile. This is really bad it doesn't crash, so someone could post an issue on gmaps api issues.
Try to wrap call to getProjection in try-catch to see it.
Because you should not interact with GoogleMap outside of main thread, you will have to find another way to achieve, what you want to achieve...
Anyway, I can imagine no good reason for a need to call getProjection in getTile. Maybe another question describing your real problem?

Getting Coordinates From Button Press Not Working

I am pretty new to Android Development, and I've tried to make a method in my Android Application, where you press the button and get coordinates (Longitude and Latitude). But the program stops working on the emulator when I press the button.
I am probably just doing something wrong here. Looking through the Callstack didn't help me. It was simply too cluttered with...a lot of useless information.
How do I fix this?
public void onLocateByGMapButtonClick() {
LocationManager mloc = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
List<String> providers = mloc.getAllProviders();
Location loc = new Location(providers.get(0));
double loTude = loc.getLongitude();
double laTude = loc.getLatitude();
String newCoords = loTude + "," + laTude;
location.setText(newCoords);
Toast.makeText(this.getBaseContext(),"Location have been updated!",5);
}

The reason you application is crashing is probably because you are receiving a null pointer exception.
You have to understand that a GPS fix is not an immediate process, it might take time and in this time you don't have a location to work on unless you use the getLaskKnownLocation method (which maybe return null as well).
So what you need to to is or use:
Location loc = lm.getLastKnownLocation(provider);
or implement a LocationListener that will fire as soon as a new location update arrives.
Tutorial: http://www.vogella.com/articles/AndroidLocationAPI/article.html