Android Studio "cannot resolve symbol String"

Question

I have a small project that was started in Eclipse. I then exported it to a gradle file, and imported it to AS (0.5.7).

At first, not much seemed to work as it should, but after a "build => make project", I didn't seem to get any highlighted errors or so.

So I tried to run the app to an emulated device. Well, the device never launched, and now I get red squiggly lines under mentions of "String", "ArrayList" etc, saying it "cannot resolve the symbol".

What the f?

I have tried cleaning and rebuilding, as well as "sync project with gradle files".

Where do I go from here? I want to get going with developing in AS so bad!

edit: Screenshot of project setup: http://i.imgur.com/ycNyPaT.png

Contents of build.gradle:

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.9.+'
    }
}
apply plugin: 'android'

dependencies {
    compile fileTree(dir: 'libs', include: '*.jar')
}

android {
    compileSdkVersion 19
    buildToolsVersion "19.0.1"

    sourceSets {
        main {
            manifest.srcFile 'AndroidManifest.xml'
            java.srcDirs = ['src']
            resources.srcDirs = ['src']
            aidl.srcDirs = ['src']
            renderscript.srcDirs = ['src']
            res.srcDirs = ['res']
            assets.srcDirs = ['assets']
        }

        // Move the tests to tests/java, tests/res, etc...
        instrumentTest.setRoot('tests')

        // Move the build types to build-types/<type>
        // For instance, build-types/debug/java, build-types/debug/AndroidManifest.xml, ...
        // This moves them out of them default location under src/<type>/... which would
        // conflict with src/ being used by the main source set.
        // Adding new build types or product flavors should be accompanied
        // by a similar customization.
        debug.setRoot('build-types/debug')
        release.setRoot('build-types/release')
    }
}

Answer 1

There is simpler and I think more correct way:

Just select menu item 'File/Invalidate Caches/Restart...'

For me this successfully resolved the issue (was caused by surprising power off of PC)

Answer 2

So project arrangement should be as follows:

• create app folder within your project.
• within app folder make following folders: libs and src
• inside src create main folder
• inside main create java and assets
• move contents of old src to java
• move contents of old libs to libs
• move res folder to src
• move AndroidManifest.xml to src
• move assets folder into src
• create build.gradle inside app folder with following content:

apply plugin: 'android'
dependencies {
compile fileTree(dir: 'libs', include: '*.jar')
}
android {
compileSdkVersion 19
buildToolsVersion "19.0.1"
}

• create settings.gradle in project root with following content:

include 'app'

• build.gradle in root should have following structure:

buildscript { repositories { mavenCentral() } dependencies { classpath 'com.android.tools.build:gradle:0.9.+' } }