Recently, I have a task as define a new custom lint rule which is quite similar with Wrong Thread rule in the default Lint rules. Thus, I have been researching about Wrong Thread rule. However, when I just started to test Wrong Thread rule in Android Studio, it did not work normally as I have already read from the document. I will describe the problem as below:
First, I annotate a method which runs in UI Thread (named as "uiMethod()") with #UiThread annotation. Besides, another method (named as "workerMethod()") run in Worker Thread is annotated with #WorkerThread annotation.
Inside uiMethod(), I invoke workerMethod(). As normally, this code must be inspected as an error due to Wrong Thread lint rule in real time, then the IDE will highlight the line in red. This behavior is exactly what I expect.
But, the behavior of Android Studio in this case processes very weird:
When I finish typing "workerMethod();" ("finish" means I have already put the semicolon down), the line is highlighted and new error is showed immediately (this behavior is normal).
However, by the time I press enter to switch to the new line, the highlight and the error notification is both off, that means the error disappeared (absolutely strange).
Then, I try "Analyze -> Inspect Code" (manually inspect the code) to inspect the whole app module. The Wrong Thread error still does not appear although many other errors and warnings are showed.
Lastly, I utilize "Run Inspectation By Name" tool and input rule name: WrongThread. This time, the rule is triggered and the line "workerMethod();" is marked as error. (this tool worked perfectly but it does not meaningful for my task).
I also test in 2 other computers which are both installed Android Studio 3.6.1, everything is the same.
Is this the bug of Android Studio or Lint framework? If it is, my task seems to be hopeless, cry cry.
Please help me, highly appreciate and thank you very much.
It actually appear to be a bug,in my case when i create a new activity the activity's class doesn't recognize the activity and deprecates it until i restart the android studio.
Another bug is with id's,when creating a new image view or textview or any other library the whole project doesn't recognize it and deprecates it.
I hope google fix these bugs soon.
Related
I know this is a rare question. Even if there are people using MyEclipse for Android development is doubted :(
The annoying thing is that after I modified my Android project (like an Activity class of a xml file), the project remained the same as it was when I imported it.
I thought there is an important feature that demonstrates this error: When I run my Android project and the console reported that "Activity not started, its current task has been brought to the front". This line occurs because the project didnt changed while as a matter of fact I did change the project and saved it.
Is there anyone has the same problem like me?
-------------add in Oct. 28-------------------
This was what I did: first, I modified one of my activities by commenting out the Toast functions; and then, I ran it however the Toast line still showed on my Genymotion emulator
Here's an odd issue I can't seem to find any information on.
I'm working on an Android app with a friend who uses Eclipse -- I use Ant and the Android command-line tools. Sometimes when I checkout code that was written by him and the project.properties file gets pulled into my local workspace, I'll have to change the path to the libraries back to where they're at on my machine, as it gets automatically set for him via Eclipse. This may be of use to know in light of what just started happening when I try to launch 'monitor' as I've always done; I get this error dialog box that pops up and says: An error has occurred, please see the logfile: /home/user/.android/monitor-workspace/.metadata/.log
So I did. It was, after I'd tried to launch monitor several times to no avail, a really long logcat-like file of Java traces. I cleared them out, thinking that perhaps it had run over its own max size for internal monitor data, but that didn't stop it crashing. A new set of errors just gets appended.
This is the first time this has ever happened, and unlike essentially every other Android problem I've had, I can't seem to find any existing information on it. The device monitor now seems to want to be integrated into Eclipse. I don't use Eclipse so I'm not sure how the monitor runs within it, or whether I'm correct in assuming that some configuration file somewhere needs to have a line changed (or whatever).
Here's the content of the logfile:
http://pastebin.com/JitCWrGg
Could anyone lend a word of advice?
Many thanks!
I understand there is the LogCat view to check the messages logged but I can't make sense of it.
When debugging (I use Java primarily) I've been accustomed to stepping over each line of code and finding out the exact point where the program crashes and then doing something about it.
How can I do this with Android development? Is there a way to precisely locate the line which is causing the application to crash?
I can't understand what to make of/how to read the LogCat messages and when I try to step over (using the F9 key or the 'Debug' option in Eclipse) it keeps opening new tabs for inbuilt classfiles (like Instrumentation.class etc) and after pressing F6 a few times over again the app crashes showing 'The application has stopped unexpectedly. Please try again'
Can someone tell me if there's something to be done in a way that I'm not doing here?
Thanks!
Btw if it helps, here's the generated log:
http://pastebin.com/EaqaWUdS
You are using a resource id that doesn't exist at line : 93 of com.site.custom.ModAdapter.getView(CustomListProjectActivity.java
--EDIT : add explanations
You will read a logcat stack trace in the same way as you did in Java : read bottom up and the culprit is the last line of your classes (before the code gets into the android sdk code).
You can do it the other way around, and start from top, stopping at the first class of yours and discarding android classes.
The same reasoning applies when debugging : step into your methods if needed and step over all methods of the SDK unless you want to debug them (and usually you don't, if you really suspect a bug inside the SDK, check the source at grepcode to see the inner mechanics of the android sdk class you are interested in).
Sometimes it gets difficult to track bugs on android, especially for widget layout related bugs because you can only see the code that is executed by the android platform, no code of your is executed, only your data are read from an xml file for instance. If something breaks here, it can be harder to debug. In that case, apply the dichotomy method : remove half line, if the bug doesn't show up, then readd your lines, remove half of them, etc...
It is the same like in java. Basically you need the sources to open the java files instead the class files. Google shows you how to add the sources.
Basically you debug android while staying in your own classes. I barely look into the android classes as the most issues are, of course, located in my own classes.
So just debug like you already do but don't step into methods/classes you don't own unless you have the sources added to your sdk. Even if you have, there might be some classes that aren't open source, so you can't step into the sources there. (Basically all Google API classes)
Try the following:
Create a HelloWorld application.
Add a Log statement to the end of onCreate:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Log.d("HelloWorldActivity.onCreate()", "setContentView() completed");
}
Place a breakpoint on the Log statement.
Run the app in the emulator and note it works and step to see the Logged entry in the LogCat window of Eclipse.
Change the HelloWorldActivity to extend from ListActivity instead of Activity.
public class HelloWorldActivity extends ListActivity {
Run the app in the emulator again and note it fails to reach the Log statement.
My question is NOT why this fails. My question is, how would you go about debugging this failure? All I see in the Eclipse Debug pane is a RuntimeException. I see LogCat has a bunch of messages, but it's huge and I've searched it but can't find anything to indicate what's wrong or where in my code the exception happened. I can't find a way to display the message inside the RuntimeException or a stack trace to know which line of code initiated the exception.
I assume there must be better ways to use the tools to find errors, but I'm new and can't seem to figure out a better way to debug besides wrapping everything I code in a try/catch. I would have expected to find a message in LogCat generated by the throwing of the exception. I would have expected the Debug window to allow you to inspect the exception's contents. I'm not saying that such techniques don't exist, I'm saying I'm having trouble figuring out as a beginner how to debug and asking what techniques do exist and how do I use them?
So, simply put:
How would you find this error if you didn't already know what was causing it?
What techniques would you use to find out the root cause?
How would you go about inspecting the Exception's details?
Generally, how do you find problems in your Android code using Eclipse?
Multiple suggestions and discussion are welcomed. :)
I would have included my LogCat contents, but it's so large that's not reasonable. You should be able to easily reproduce this yourself, so I left it out. It is possible something is in LogCat to help me, but because it's so large with even running a small program, I would need a hint as to what to search for and how to interpret it when hitting an exception thrown from an API call. I see other posts that state something should be in LogCat, which while might be true, I'm not finding anything myself. If you think something should be in LogCat, please run the test yourself and copy the lines into your response that I should be finding.
Thanks.
========
Summary techniques list so far is as follows:
Invasive Techniques:
1. Place a Toast in code locations where you want to see you you've executed.
2. Place try/catch around code where you think there's a possibility of an Exception being thrown.
3. Comment out code and recompile and retest.
Non-Invasive Techniques:
1. Use the debugger. Breakpoints, variable inspection...
2. Monkey stress tester.
3. Download Android source library.
4. Use LogCat filters to see if a "Caused By" is listed.
Unclear if Available:
1. Debug version of Android library that has additional logging, assertions or other additional help.
2. Ability to inspect an Exception in Eclipse through the Debug pane or other techniques.
3. A way to define a more global try/catch exception handler.
4. Ability to debug through the Android library source code.
Not Available:
1. A non-invasive way to view the contents of an Exception or where the Exception happened.
hey,
Ineresting question. Well, first tip, you can filter what logcat tells you. For instance, you make it just show you errors by clickin in the red (e).
It also tells you where the error happened if you run your app in debug mode. It can either point you directly to your code or to android sdk. Knowing what android package caused the error is a big help.
These two just pop into my mind. hope it helps!
I was running into the same issue and found the following by Steve H. that helped out:
What happens is that when the debugger
is attached, the exception logs don't
get posted to LogCat until you
terminate the application from within
the Debug perspective. This happens
because the application doesn't
actually crash until the debugger
detaches. – Steve H Mar 31 at 15:47
------ yup, that did it. Now I see the same exception. AFTER I let the
program run through it's full crash
and exit process. It should display
that info when it halts my program and
brings up the IDE debugger screens.
Not leave me wondering and wasting my
time with more clicking around.
Eclipse has a long way to go it seems
to compete with the likes of Visual
Studio. Let's hope my patience for it
outlasts my project. Thanks for the
feedback. :) – Sebastian Dwornik Mar
31 at 17:35
Link to Question: What's wrong with debugging in Eclipse on Android?
Generally if anything throws an exception then you should probably be catering for that situation anyway, however putting try/catch blocks is a decent way of finding the specific problem.
I've found that if you don't put something in the catch block then you can't evaluate the exception in the watch variables window in eclipse. So i always put a Log call in and set a break point on that line.
public void onCreate(Bundle savedInstanceState) {
try{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}catch(Exception exception)
{
// put break point on line below so you can evaluate exception in debug mode.
Log.e(TAG, "Set content exception "+ exception.getMessage());
// note some exceptions return null on getMessage();
}
Log.d("HelloWorldActivity.onCreate()", "setContentView() completed");
}
So if your stack trace is huge then this will help. Other developers have also found that getting the source code for the sdk means you can view where the error is thrown in the main sdk code. I've not done this though.
Exceptions not caught with try/catch are errors and break the normal flow of the program.
Running in debug mode is just clicking in the bug button. I don't know if there are any "special" debug libraries. But when working with android, all "libraries" are open source so you can pretty much view anything.
The good thing about debug mode is that when an error occurs, your app is frozen right in the limbo when the error occurs. You can set set breakpoints, change your code on the fly while your program is running, which is great (Well, you can't make drastic changes like changing a method name).
The way you treat bugs and errors in android, however, can be a bit different from .NET, since the model in each one is different.
When programming to windows, apps work like small islands. You have a much direct control over the code flow (ie: you can call a modal dialog to freeze codeflow while a user inputs some data) and you can make a totally functional program using just one thread. In android almost everything runs in it's own sync. And your app must be prepared to handle stuff like receiving a phone call in the middle of execution. So, you can apply this model to debugging also: Errors (that happen due to unforsen circumstances) tend to propagate much more than in other development ambient. The way those errors are handled is different too: this is apparent when you realize that your app still runs even after throwing an exception.
Some more useful tips:
You have a very powerful tool called Monkey, a stress tool that generates "pseudo-random streams of user events such as clicks, touches, or gestures, as well as a number of system-
level events".
LogCat indicates you the "cause" of the error. The line usually starts with Caused By. If you're interested in the cause rather than the consequence, you can further filter your error reports looking for "Caused by".
Last but not least, I find the old method of commenting lines and see what happens very useful to figure things out.
hope it helps
I am a little bit new to developing for Android using Eclipse (Coming from a .NET/Visual Studio background).
My biggest problem in developing Android app is "debugging" them. Every time the emulator throws an error, there is no message, no explanation of what caused the error. I basically have to keep doing trial/error until something works.
My question is: Is there a better way to analyze the error messages that emulator shows (basically some stack trace about Dalvik)!
Also, is it possible in Eclipse [when debugging] to move the debugging cursor backwards to re-evaluate a variable or "skip" some lines of code?
Use LogCat view to see error/debugging messages. Regular console is of very limited help. Window->Show View->Other->Android->LogCat There on the top you will see some round buttons that basically can filter log from V (verbose) to E (error). You can't copy/paste from theLogCat window but you can save selected output to text file
Regarding the error messages (I'm assuming these are the messages that show up in LogCat): I've found that analysing the error messages and working your way up the list until you reach code that is yours is the most effective way to work. Frequently (for me at least) the emulator will crash and break somewhere in the OS code (which you probably don't have the source for) but you can follow the LogCat messages back to your code and start to see where the problem is. The crash may appear to happen in the OS code, but the original cause is typically you passing something wrong to the OS.
Regarding going backwards in code: nope, at least not with the my Eclipse Ganymede install
Regarding skipping code: When your in debug mode under the Run menu you can select "Step Over" (skips going into a method) , "Step Return" to exit a method and "Run to Line" in addition to setting Breakpoints by right clicking. This causes the code to run, but you aren't single stepping through it. Otherwise the only way to "skip" lines of code is to comment it out. I believe you can also change the value of variables in the debugger, but I've never tried personally. This may give you the desired effect.
Try closing all unrelated project, switch off eclipse and then do a clean and build for the project in picture.