Android Studio suddenly cannot resolve symbols

Question

Android Studio 0.4.2 was working fine and today I opened it and almost everything was red and the auto-completion had stopped working. I look at the imports and AS seems to be telling me it can't find android.support.v4 all of a sudden (offering me the option to remove the unused imports). (android.support.v7 seems to be fine though).

Things I have tried:

• Rebuilding the project
• Cleaning the project
• Syncing with Gradle Files
• Closing the Project, closing AS and relaunching / reopening
• File > Invalidate Caches / Restart
• Examining Lint, didn't see anything obvious
• Double checking all support libraries are up to date in the SDK manager
• Examining my Build.gradle, although no changes and it's the same as usual, the way it was working all the time.

Here it is in case it's relevant:

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.7.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 19
    buildToolsVersion '19.0.0'

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion 19
    }
}

dependencies {
    compile 'com.android.support:support-v4:19.0.0'
    compile 'com.android.support:gridlayout-v7:19.0.0'
    compile 'com.android.support:appcompat-v7:19.0.0'
    compile 'com.google.android.gms:play-services:4.0.30'
    compile project(':libraries:facebook')
    compile files('libs/core.jar')
}

When I hit "Sync with Gradle" and open "Project Settings" I get a red error telling me I have duplicate library references and to remove the unused ones..

My project compiles and runs fine but I really need the autocomplete working!! Does anyone have any suggestions?

Answer 1

None of the things mentioned earlier here did actually work for me. But then I found this menu entry in the file menu Invalidate Caches/Restart which appears to have fixed the problem.

I don't really know what happened in the background but when Android Studio started up again the status bar said Indexing... for a minute or so which apparently did wonders.

For reference I'm using Android Studio 0.5.4.