Develop Reference

App Crashes with no Stack Trace

Preface I've changed the title. It is hard to understand why, while debugging, sometimes uncaught exceptions print 'FATAL EXCEPTION' to the Logcat and sometimes they don't.
The simplified example below crashes when I get to the line client1.getInputStream(). There is no stack trace or other indication inside of Logcat as to what went wrong. I am running Android Studio 3.0.0beta4.
Why is it crashing? (update - crash was due to a SecurityException)
And why does Logcat not show a stack trace or
other error?
Update
Okay, I figured out why it crashes. I added catch(Exception ex) {...} and found that an exception was in fact being thrown, for I had forgotten to test for it. Stupid error, I didn't include INTERNET permission in the manifest.
So, I would still like to know why I would get no error indication for the unhandle exception. The app just quietly disappears.
Edit One commenter says
In java, unhandled exceptions are not printed
Here is the logcat message when I force an unhandled NullPointerException
FATAL EXCEPTION: Thread-6729
Process: com.example.myapplication, PID: 30824
java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.InputStream java.net.URLConnection.getInputStream()' on a null object reference
at com.example.myapplication.MainActivity.GetDataAsyncFromPlaystore(MainActivity.java:79)
at com.example.myapplication.MainActivity$1$1.run(MainActivity.java:42)
at java.lang.Thread.run(Thread.java:818)
So, why not for SecurityException?
Edit2 Just to make things more confusing, I've discovered that when I set a break point prior to the exception point, then step through the code and step over the offending line (the one causing the SecurityException), the App abruptly terminates with with no indication as to why. If however, I hit F9 before reaching the offending line, I do, in fact, get a "FATAL EXCEPTION" message logged in Logcat. (Therefore, I've added back the "android-studio" tag to the question.)
So, same question, slightly different wording: Why does the exception print a 'FATAL EXCEPTION' message when debugging one way, but not the other?
The (simplified) code
public void GetDataFromWebsite()
{
Uri queryUri = Uri.parse("https://play.google.com/store/search?q=Planning&c=apps");
try {
URL queryUrl = new URL(queryUri.toString());
URLConnection client1 = queryUrl.openConnection();
InputStream in = client1.getInputStream();
Log.d("Test", "Okay");
} catch (MalformedURLException muex) {
Log.e("Test", "Malformed Url", muex);
} catch (IOException ioex) {
Log.e("Test", "IO Error", ioex);
// } catch(Exception ex) {
// Log.e("Test","Other Exception", ex);
}
}
NOTE:

You are just catching MalformedURLException and IOException. So you won't get other exceptions.
Catch with Exception you will get a trace.
UnHandled exception not printed in android log cat. you can print UnHandled exception by UncaughtExceptionHandler. Here is a like to implement UncaughtExceptionHandler: Logging unhandled exceptions in Android Activity
There is no relativity between NullpointerException and SecurityException. How it will get caught by SecurityException.

DuplicateIdentifierException handled in android

My rest call throws DuplicateIdentifierException but there is no way i can handle this exception in try catch that have been provided by android. Is there any way to catch such exception

Hide thrown exception messages on Android

Is there a way to block the displaying of thrown exception messages (with all the stacktrace and everything) for an android app ?
EDIT:
Well, I know I can use try/catch block to do that that's not what I want.
Is there like a way to specify that in mafinest file or maybe in project settigs or smthng ?

you can wrap your code in try catch
try {
// code that might throw an exception
} catch (Exception e) {
//don't print the exception
}

Stack trace not visible on Eclipse

Hello everybody I am new of Eclipse and Java. I want to see the stack trace of a ClassNotFoundException but I cannot see it on LogCat.
I tried all the possible output here in the code that I cannot see absolutely nothing in the logcat.
try{
Class.forName("com.mysql.jdbc.Driver");
}
catch(ClassNotFoundException e){
e.printStackTrace();
Log.d("appcani","I am here");
Log.d("YOUR_APP_LOG_TAG", "I got an error", e);
}
It seems it doesn't go inside the catch but without the catch it gives the ClassNotFoundException so it should go inside the catch.
I already tried to use:
catch(Exception e)
but it doesn't work as well

How to handle exception and prevent crashing app

I am using the Amazon AWS SDK to download images from S3. Occasionally, when an image is not found an exception "AmazonS3Exception: Status Code: 404" is thrown. However, this seems like an exception which should not crash the app. How can I handle this exception so that it does not crash the app? Apologies, Im a noob to Java & Android.

To follow up on type-a1pha's answer:
If you want to handle an exception gracefully, you would use a try-catch statement. It works something like this:
try {
// Here you put the code that may throw an exception
} catch (AmazonS3Exception e) {
// Looks like we errored out, log the exception and
// tell the user that we 404'd
Log.e(TAG, "Error fetching file from Amazon S3", e);
Toast.makeText(context, "Error 404 while fetching file: file not found", Toast.LENGTH_SHORT).show();
// Insert any other code you need here to recover from the error
} finally {
// Note that the finally part is optional but useful if you want
// to do something after the try-catch statement is finished
// for example, if you were using an inputStream:
inputStream.close();
}

try{
//code throwing exception
} catch (AmazonS3Exception) {}