Develop Reference

Why Android Studio is showing errors "everywhere in code" after last update?

Yesterday I have updated my AndroidStudio IDE and after that I see strange error everywhere, even on fresh project:
there is also message:
Cannot access 'android.app.Activity' which is a supertype of 'pl.testapp.MainActivity'. Check your module classpath for missing or conflicting dependencies. Cannot access 'java.lang.Object' which is a supertype of 'pl.testapp.MainActivity'. Check your module classpath for missing or conflicting dependencies.
I can build project but writing code where everything is underlined is horrible ;p. I have already tried to reinstall IDE but with no result. Have you ever experienced that?

For anyone else running into this in 2021 and beyond.
I found that one of my Sdk's was corrupt.
To fix:
File -> Project Structure (or Cmd + ;)
Modules on left hand side
Properties tab
Change "Compile Sdk Version" to a different one
For me, changing this made all the errors disappear.

This usually happens when the IDE's executable is moved to another folder. Close the IDE and rename the folder containing the IDE settings to recreate it.
In my case the path to the settings folder was:
/home/myLinuxUser/.config/Google/AndroidStudio2020.3
So I renamed "AndroidStudio2020.3" to "AndroidStudio2020.3__OLD". After that, go to the IDE again and open your project.

This error indicates that expected imports aren't available on the classpath for what ever reason:
One cause could be that the InelliJ IDEA cache got messed up.
Solution: Go to File->Invalidate Caches / Restart and check if the problem has been solved after restart.
Other cause could be that you deleted your SDK. Check if your Android-SDK ist still configured properly:
Let me know, if I helped you!

OK I have already fixed this issue. I had unninstalled AndroidStudio, deleted all folders related to IDE and also deleted SDK folder, after that installed everything fresh once again. That was very strange, that was the first time for me when Update broke IDE... Thank You all of You :)

"AndroidManifest.xml doesn't exist or has incorrect root tag" Error

I am new to AndroidStudio AND Gradle.
I imported a project from eclipse, created a module, and tried to run the project, but I got this error:
AndroidManifest.xml doesn't exist or has incorrect root tag
I have been looking at this previous solution for it:
How to build an android library with Android Studio and gradle?
But that solution is WAY too advanced for me.
Could someone please help me understand in simpler terms what is going wrong and how I can fix it?
Thank you!
Update after one of the answers:
These are the options I have under the build menu:

clicking on Sync project with Gradle files button will solve your problem.
That button is under File section on Android Studio 3.6.1

Close your Android Studio
Goto C:\Users\user\.AndroidStudioX.X\system and DELETE the cache
folder
Launch the Android Studio
Goto Build (menu) -> Clean Project when done click the
Build (menu) again and click rebuild project.
That should solve the problem.

For me the issue went away once I opened the android folder of the project in Android Studio to run the project.
So basically, because I was trying to run the Android project from the Root folder, it gave me the error. We need to run the project by selecting the android folder of the project only.
Hope this helps someone!

Click on File > Invalidate Cache/Restart, and that's it. Your project should start working.

For me clicking on Sync project with Gradle files button did not solve the problem alone.
After Syncing project with Gradle files, I explicitly had to invalidate the cache and restart studio. Only after this action, the red cross-mark over configuration disappeared and everything started working.

In my case, my android project got corrupted and some of the files were showing characters, binary numbers, etc. I tried the following solutions
Invalidate & Restart
Rebuild Project
Sync with Gradle File
But none of the above solutions worked for me.
Then I just deleted the cache folder under C:\Users\username\.AndroidStudio3.6\system
and all the invalid characters disappeared and the actual contents of all the files were displayed. This solution worked for me.

Every Android project needs a file called AndroidManifest.xml to tell Android about itself. Either your project doesn't have one, or it's not in the place that Android Studio expects it to be. Try to find it, and move it to the root folder of the project.

1.Check whether the manifest file is there or not.
2.If it is there, check whether the package name is correct or not..
3.If you project has small number of classes, then you create new project in android and then copy paste your code from eclipse. It will be simple. But it is recommended only for small project.
And finally click 'Sync' in the Gradle file. Followed by Rebuilding the project will do a trick.

In my case the Manifest file seemed to be corrupted or maybe its meta data. Trying to open it in Android Studio will show some characters that you see when opening a binary file with a text editor, for ex. Anyway, my project is under Git, so I just deleted it and restored it back, problem fixed.

Go to C drive click User then select your android studio folder then select System find Cache folder and delete this folder before doing this close your android Studio.It will surely work.

I also had this problem, things I tried:
I delete user->gradle-> delete cache folder
Android studio-> file-> Invalid cache/restart
Using my problem is get resolved

I also had this problem, things I tried:
Syncing the file with gradle
Invalidate/Restart
But the problem was still there in the manifest folder-> manifest.xml file it had only 1 line.
So I went to User-> your_username -> Android Studio v -> caches and Deleted the cache folder.
Started Android Studio, and my problem was gone.
But I am not sure which of these might solve yours.

I have opened AndroidManifest.xml in file editor. Add some letters, save it, then android studio found AndroidManifest.
After this I can build project successfully

if your AndroidManifest.xml looks wierd than you can try checking local history or git history. by doing that you can copy paste the previous version AndroidManifest.xml

Experienced that too, there is a line on your manifest code that's incorrect, simply go through it and make necessary corrections.

Android Studio says "cannot resolve symbol" but project compiles

I'm importing twitter4j in AndroidStudio, using the following in my build.gradle:
dependencies {
compile 'com.android.support:support-v4:18.0.+'
compile files('libs/twitter4j-core-3.0.4.jar')
}
The project compiles fine, and I can create twitter objects without a problem. However, in Android studio, anything referencing that library shows "cannot resolve symbol" and displays in red. What do I need to do to get Android Studio to recognize the library?
I have already tried rebuilding the project, ./gradlew clean, and closing and re-opening my project.

No idea if this will work or not but my only thought so far: right click the jar file in file tree within AS and select "Add as library..."
EDIT: You can do "File" -> "Invalidate Caches...", and select "Invalidate and Restart" option to fix this.
EDIT 2: This fix should work for all similar incidents and is not a twitter4j specific resolution.

Try changing the order of dependencies in File > Project Structure > (select your project) > Dependencies.
Invalidate Caches didn't work for me, but moving my build from the bottom of the list to the top did.

This is what worked for me.
In the Project panel, right click on the project name, and
select Open Module Settings from the popup menu.
then change the Compile SDK Version to the minimum version available (the minimum sdk version you set in the project).
wait for android studio to load everything.
It will give you some errors, ignore those.
Now go to your java file and android studio will suggest you import
import android.support.v4.app.FragmentActivity;
Import it, then go back to Open Module Settings and change the compile sdk version back to what it was before.
Wait for things to load and voila.

For mine was caused by the imported library project, type something in build.gradle and delete it again and press sync now, the error gone.

I also had this issue with my Android app depending on some of my own Android libraries (using Android Studio 3.0 and 3.1.1).
Whenever I updated a lib and go back to the app, triggering a Gradle Sync, Android Studio was not able to detect the code changes I made to the lib. Compilation worked fine, but Android Studio showed red error lines on some code using the lib.
After investigating, I found that it's because gradle keeps pointing to an old compiled version of my libs.
If you go to yourProject/.idea/libraries/ you'll see a list of xml files that contains the link to the compiled version of your libs. These files starts with Gradle__artifacts_*.xml (where * is the name of your libs).
So in order for Android Studio to take the latest version of your libs, you need to delete these Gradle__artifacts_*.xml files, and Android Studio will regenerate them, pointing to the latest compiled version of your libs.
If you don't want to do that manually every time you click on "Gradle sync" (who would want to do that...), you can add this small gradle task in the build.gradle file of your app.
task deleteArtifacts {
doFirst {
File librariesFolderPath = file(getProjectDir().absolutePath + "/../.idea/libraries/")
File[] files = librariesFolderPath.listFiles({ File file -> file.name.startsWith("Gradle__artifacts_") } as FileFilter)
for (int i = 0; i < files.length; i++) {
files[i].delete()
}
}
}
And in order for your app to always execute this task before doing a gradle sync, you just need to go to the Gradle window, then find the "deleteArtifacts" task under yourApp/Tasks/other/, right click on it and select "Execute Before Sync" (see below).
Now, every time you do a Gradle sync, Android Studio will be forced to use the latest version of your libs.

When i lived to this problem(red color codes but they work correctly) in my project;
As first, i made it that (File -> Indicate Cashes) --> (Invalidate and Restart).
As last, i resync my build.gradle file in my app. After problem was resolved.

Invalidate Caches / Restart didn't work for me this time.
Found a solution like this:
Remove the compile *** or implementation *** line in build.gradle.
Clean and rebuild. Errors should be raised here.
Add the line in step 1 back to build.gradle.
Clean and rebuild.
Weird...

This problem happened for me when my Glass project was not using the SDK installed in Android Studio's default location. I was using another location I had previously from ADT, since I was trying to avoid re-downloading everything. Once I pointed the project back to the SDK location in Android Studio's install location the problem went away.

I had this problem for a couple of days now and finally figured it out!
All other solutions didn't work for me btw.
Solution: I had special characters in my project path!
Just make sure to have none of those and you should be fine or at least one of the other solutions should work for you.
Hope this helps someone!

I had the very same problem recently with Android Studio 1.3. The only working solution was to remove the .gradle and .idea folders and re-import the project into Android Studio.

For those, who tried the accepted answer and have no success,
I tried also the accepted answer and did not work for me. After that, I updated my project with the repository and synchronized the project and the could not resolve warnings are gone.

Invalidate Caches didn't work for me (this time). For me it was enough changing the gradle and syncing again. Or https://stackoverflow.com/a/29565362/2000162

If nothing else helped, you could do as Android Studio suddenly cannot resolve symbols recommends:
Exit Android Studio
Back up your project
Delete all the .iml files and the .idea folder
Relaunch Android Studio and reimport your project

In my case, I had created a new file using the GUI and defined an interface within the file. I kept getting this symbol error because the file was not a "java" file. It had no extension on it at all.
After modifying the file extension to ".java", the system correctly finds the symbols.

In my case the jar file did not have a META-INF/MANIFEST.MF file. After adding one, it worked!

For my case working with AndroidStudio 2.2.3 the solution was to change the gradle wrapper/distribution to use local one in the Gradle Settings (despite of being "recommended").

This worked for me--
(File -> Indicate Cashes) --> (Invalidate and Restart).

I tried Invalidate cache/restart or clean Project -> rebuild project. These didn't work for me.
The final solution was open Project window on the left side of IDE, under Project mode, delete .gradle and .idea folder, THEN you can invalidate caches and restart. This fixed it.

Change compile to implementation in the build.gradle.

Changing the language injection settings worked for me.
Place the cursor on any of the red underlined code and Alt + Enter
Now select Language Injection Settings and a window will open as shown below.
Uncheck the selected option and click Ok
Hope this helps somebody.

It happened to me when I removed the whole files in .gradle/caches, then studio downloaded the dependences. The dependences not showed in the External Libraries but I can build App successfully. rebuild clean Invalidate and Restart have no effect. I solved the problem by the steps:
Close Android Studio completely
Remove .idea package in your project
Restart Android Studio

I have tried this but nothing worked for me:
Invalidate Caches / Restart
Changing the order of dependencies
Sync project with Gradle Files
Clean -> Rebuild Project
In my case, just do:
Delete all files in .idea/libraries folder
Rebuild Project

For me I updated gradle-wrapper.properties into 4.4
distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-all.zip

I found easiest way
Identify the library which is causing syntax error in Studio.
For Example if AppCompatActivity is showing error then you will perform below operation on AppCompat Dependency.
Remove dependency which is showing syntax error & Sync.
Add again & Sync.
That's It, error gone!
Before
After

None of the answers above works for me.
After a lots of attempts, I upgraded com.android.tools.build:gradle in Project/build.gradle from 2.3.0 to 3.0.1, and it works.
I guess the version of the com.android.tools.build:gradle should be match to the version of AndroidStudio, and my AS version is 3.2.1

I tried all of the posted solutions and none of them worked for me. (Though invalidate caches does normally. This time it made no difference). After trying everything posted here the "Error cannot resolve" were still present. And the project did build and run successfully, only the IDE seemed to be confused, not the actual app or device.
My Version of Android Studio is 2021.3.1:
The solution that did finally work for me was updating the "Android Gradle Plugin Version" configuration inside of File -> Project Structure.
It was originally 3.2.1 when it wasn't working. I updated it to 3.5.3 because I have another project that was working fine and it was on that setting.
After making this change and then sync'ing gradle the symbols not resolved error goes away and the IDE once again knows what those classes are.

Closing all files and closing Android Studio works for me.

You need to restart Android Studio.

Eclipse error : Your project contains error(s),please fix them

I am using Eclipse Classic 3.7.2 working only on Android. I use Ubuntu as my OS. When I run any basic Android application on Eclipse say "Hello World", it results an error called Your Project contains error(s), please fix them before running your application.
Now I have googled and checked here and may others but I did not get the solution.
I also tried Project > clean... but it isn't working.
Windows->Show Views->Problems shows 2 errors:
Error generating final archive: java.io.FileNotFoundException:/home/android/Desktop/helloworld/bin/resources.ap_does not exist.
Unable to parse aapt...

It may be be because of Eclipse's debug certificate expiration.
Please look at to my this answer.

Close and restart Eclipse. It works everytime !
Its bug with deleting android projects I think.

I have faced exactly same type of issue. Just update your eclipse ADT plugin to latest version.
After update clean build the project.

Go to your .android folder and delete your debug certificate. In my computer it is in this path
E:\Users\(ur profyle)\.android
Inside that there is a file name 'debug.keystore'. Delete that,clean and try to build the project again. Sometimes this error is caused when the certificate expires.

You need to update your Eclipse to the latest available version(Indigo) and then need to update the ADT(level 16 I think), as the latest ADT updates works on Indigo only. After the updates close and reopen the Eclipse, it should work now.

Go to Project Properties -> Java Build Path
Select Libraries and remove Android Dependencies
After this my problem solved.
The error was because of updating

Set your Android sdk path once again and restart Eclipse. It fixes the issue (window-preferences-android-sdklocation).
Or, just update your Android tools and restart Eclipse works.

Check your libs folder ..
some libraries cause this ,
it happened to me once and i was use Apache POI .. i tried to delete the jars from libs folder and it's worked ..

I had this problem in Eclipse after executing Project => Clean... That option deletes all the compiled stuff from your project and, therefore, the java classes start looking like if they all have errros.
To fix that problem I had to:
1. open my java clases and XML layout files(for android dev)
2. do a small change, something like a adding a space
3. Hitting Crt+S to ask eclipse to save and compile the class once again.
This solution may or may not work for you. I recommend looking at your specific problems using the Problems tab of Eclipse (Found at Windows=>Show View=>Problems) since it tells you about the exact errors and other very useful information.

If you're using android support library make sure you have not added jar files ( android-support-v4.jar and android-support-v7-appcompat.jar ) in your libs folder.
you only need to add android-support-v7-appcompat as library on your project.
It worked for me the time I had the same issue

My project had no errors in it but I noticed another open (unrelated) project which did have errors. I closed that project and my other project worked fine again.
Now the "unrelated" project used to be related but I'd removed the dependency ages ago. Closing it solved my problem so I have to assume there is some Eclipse bug in there somewhere which is still linking to it in some way. I'd say if I created a new project and copied everything in it might have achieved the same result.
As a test for yourself.. maybe close all other projects except the one you are working on.

Your project contains error(s), please fix it before running it

I am developing a simple Android application. But when I run Eclipse, it shows the following error:
Your project contains error(s), please fix it before running it.
I can't find any error in my project or there is no error in my application.
There is a red cross under the application name but it is not under another file name.
Does anyone else have this issue?

That usually comes from errors in the build path.
If you're using eclipse, there is a view you can add that lists all the errors called "Problems":
Otherwise, you can try to clean the project, and that usually solves a few problems.
Finally, if you add or alter resources from outside your IDE, you'll want to reload the resources and clean.
EDIT (Comment by anonymous user)
This can also be caused by an out of date "Debug Certificate" fixed as follows:
IF ALL FAILS THEN THIS GOTTA BE THE SOLUTION:
Delete your debug certificate under ~/.android/debug.keystore (on Linux and Mac OS X); the directory is something like %USERPROFILE%/.androidon Windows.
The Eclipse plugin should then generate a new certificate when you next try to build a debug package. You may need to clean and then build to generate the certificate.
This is also another fix for the "setContentView(R.layout.main);" error that says it cannot find R.layout.main when it is actually generated. (R cannot be resolved to a variable).
This is also another fix for the error "Your project has errors..." and you cannot find any.
Clean and rebuild are still necessary after generating a new debug certificate.

First go to Window -> Show View -> Error Logs in menu. It will display error logs if you have any. Then try to clean the project and build it again.

Well, in my case some libraries were addressed twice in the:
Project >> Properties >> Java Build Path >> Libraries
I just had to remove the duplicate and it worked fine without any cleanings or refreshing.

I saw this with an existing project. I had made a few edits, but hadn't imported anything new. Restarting Eclipse didn't help.
Project->Clean did solve the problem.

I come across this error often when I import a new project in my workspace.
Reason: Some necessary files (Like R.Java) is not generated in its respective packages.
Cure: Clean and build projects, All the files that needs to be auto generated will be there on place after building the project.
Best Luck.

This is happened to me. After format of my system,
When i import project it shows same error
remove first debug.keystore file then goto -
Project -> Project properties -> select library -> remove -> add again libraries.
It's working for me......

Go to projects menu, click on clean menu item.
After that close the eclipse and reopen and try compiling..
It is software glitch you find some times.

it can also happen if you move required files. Simply check Problems View (menu window -> show view -> Problems) as told here

I had this exact same problem. One solution that would work would be to create a brand new project, but I don't think there's any need for that. For me the problem was that the debug certificate that gets auto-generated had expired. Deleting this file allowed Eclipse to rebuild that file, which solved the problem. You can't run an app with an invalid certificate, whether it be a debug or release certificate. Note that cleaning my project did not work. For more information, see:
"Debug certificate expired" error in Eclipse Android plugins

Recently I came across this error. I was really in a corner with no help, then I figured it out. This error can occur for the following reasons:
An error in the project code
Improper linking of external library files to the project
Most important: if your debug.keystore file is expired.
The first 2 cases are easily identifiable but the third one is like searching a black box in a dark room.
So in addition to Project -> Clean, remove your debug.keystore file also.
I am using Mac + Eclipse so to remove, I wrote the command rm ~/.android/.debug.keystore in a terminal.

Is there a way to ignore existing errors in project. Something similar what eclipse allows in case of java projects.
In my case the errors exist in jni directory. The errors are shown even though ndk-buid succeeds. So all i want to do is to ignore the errors reported by eclipse.
If the errors are indeed errors then i should get unresolved symbols during ndk-build.
I have ensured standard android includes are there in include path.
Also my project is of type android/c/c++.
I have two builders associated with the project
1. statndard android builder
2. custom ndk builder that ive explicitly created.

Simulate your self some error in class. Then save it and it would show more errors than you simulated. For me it was incorrect import and this helped.

I have had a similar problem.
Under "problems" tab I have found an error saying "Error generating final archive: Debug Certificate expired on 2/22/12 1:49 PM"
So my advice is to look in the problems tab to get some more info.
Bye

If none of the above solution work, you should check the READ ONLY property of the Project folder, if it is Read-Only, the compiler will not be able to overwrite the resources, R.java and other dex APK etc files and hence this will occur..
This happened to me and I fixed after a long struggle..
Happy Programming.

For some reason eclipse only showed a ! error on root and didn't specified what error it was.
Go in Windows -> Show Views -> Problems. You might find all previous errors there, delete them, do a clean build and build again. You'll see the exact errors.
Eclipse shows an error on android project but can find the error

I had this exact problem when trying to run the Doodlz app, from the book Android for Programmers, on Mac OS X with Eclipse Juno.
After downloading and unzipping the demos from the book, I forgot to change the permission of the files. They were read-only on my system so this was the first issue.
The second issue was solved by selecting a build target on Eclipse. This was fixed by going to: Project > Properties , and clicking the Android field on the left panel to be able to select one option as the Project Build Target, which in my case was:
Target Name Vendor Platform API Level
> Google APIs Google Inc. 4.0.3 15
Then cleaning and rebuilding the project showed no errors.
Finally, to run the app right-click the package (at the Package Explorer tab) and then select:
Run As > Android Application

Simply Deleted my debug certificate under ~/.android/debug.keystore and Project->Clean did solve the problem.

Delete the .android folder from your Documents&settings\User\ on XP and \User\ on Win7. Recreate the AVD again and create a new project.

What caused this problem for me was none of the above, but simply that I'd left the "debuggable" attribute to false in the manifest.xml file after doing a release. D'oh!
Of course neither the LogCat, Error log, Console, or Problems window alerted me to this..

I had the same error, when I copied a project to another computer.
I then checked all properties of the project on both machines, and the only thing that was different was the order of items in Java Build Path - tab Order and Export.
I moved the items Android X.X.X and Android Dependencies above the other 2 in the list (in my case, src and gen folders) and voila, it worked again!
I'm not really sure if the different order was actually the problem, but at least changing it (and saving the properties again) seemed to help...

I had the exact same problem after updating the SDK and ADT.
My issue was resolved by deleting the .android folder (hidden) under C:\Users\USERNAME\

This happened to me when I was experimenting with Maven.
Right click project -> Maven -> disable maven nature
corrected the problem for me.

Yes, this is a rather cryptic message. If you've got a faulty project (say one you've been working on in the past) then you'll get this message (and no messages in your current project's Problems / Error Log panes).
You may just want to run your current project. This may be perfectly fine. Just click on the down arrow to the right of the Run button to select your project.

Try changing your workspace. I am not sure this is the exact solution . I did face the same issue for sometime untill i changed my workspace.

In my case, it happens with ADT 22.
I choose not to create Activity.
After I remove the "appcompat_v7" as library project. I works.

I had similar problem where I couldn't run my project yet didn't see any problems in the code. In Error Log panel it said something like "Cannot add P/ to the list of segments P/ in as a parent".
Restarting Eclipse solved the problem.