Android Studio unable to resolve error ':app:preDexDebug'

Question

I'm just moving on from Eclipse to the intimidating Android Studio and have trouble getting rid of, what appears to be a fairly common error.

Error:Execution failed for task ':app:preDexDebug'.
> com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command '/usr/lib/jvm/java-7-oracle/bin/java'' finished with non-zero exit value 1

I looked all over and have tried various solutions ranging from simply restarting my Studio, Invalidating and clearing the cache, removing the JARs and trying to add them again, but so far nothing works. I'm very new to this IDE so I'm not even sure how it works and what the build files are supposed to look like.

Here's my current build.gradle (Module:app)

apply plugin: 'com.android.application'

android {
    compileSdkVersion 21
    buildToolsVersion "21.1.2"

    defaultConfig {
        applicationId "com.example.culami"
        minSdkVersion 21
        targetSdkVersion 21
        compileOptions {
            sourceCompatibility JavaVersion.VERSION_1_7
            targetCompatibility JavaVersion.VERSION_1_7
        }
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
}

dependencies {
    compile 'com.android.support:appcompat-v7:21.0.3'
    compile 'com.android.support:support-v4:21.0.3'
    compile files('libs/WebSocket.jar')
    compile files('libs/android-support-v13.jar')
    compile files('libs/json-org.jar')
    compile files('libs/socketio.jar')
}

The project was imported from Eclipse and the reason for doing so was that I was facing some build issues with json-org.jar and WebSocket.jar. I wasn't able to fix this and the issue is still open. I'm not sure how do add these dependencies via gradle because the github page doesn't really say how.

Here's the output from the Gradle console.

Executing tasks: [:app:assembleDebug]

Configuration on demand is an incubating feature.
:app:preBuild UP-TO-DATE
:app:preDebugBuild UP-TO-DATE
:app:compileDebugNdk UP-TO-DATE
:app:checkDebugManifest
:app:preReleaseBuild UP-TO-DATE
:app:prepareComAndroidSupportAppcompatV72103Library UP-TO-DATE
:app:prepareComAndroidSupportSupportV42103Library UP-TO-DATE
:app:prepareDebugDependencies
:app:compileDebugAidl UP-TO-DATE
:app:compileDebugRenderscript UP-TO-DATE
:app:generateDebugBuildConfig UP-TO-DATE
:app:generateDebugAssets UP-TO-DATE
:app:mergeDebugAssets UP-TO-DATE
:app:generateDebugResValues UP-TO-DATE
:app:generateDebugResources UP-TO-DATE
:app:mergeDebugResources UP-TO-DATE
:app:processDebugManifest UP-TO-DATE
:app:processDebugResources UP-TO-DATE
:app:generateDebugSources UP-TO-DATE
:app:compileDebugJava UP-TO-DATE
:app:preDexDebug UP-TO-DATE
:app:dexDebug
AGPBI: {"kind":"SIMPLE","text":"UNEXPECTED TOP-LEVEL EXCEPTION:","position":{},"original":"UNEXPECTED TOP-LEVEL EXCEPTION:"}
AGPBI: {"kind":"SIMPLE","text":"com.android.dex.DexException: Multiple dex files define Landroid/support/annotation/AnimRes;","position":{},"original":"com.android.dex.DexException: Multiple dex files define Landroid/support/annotation/AnimRes;"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:596)","position":{},"original":"\tat com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:596)"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:554)","position":{},"original":"\tat com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:554)"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:535)","position":{},"original":"\tat com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:535)"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:171)","position":{},"original":"\tat com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:171)"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.merge.DexMerger.merge(DexMerger.java:189)","position":{},"original":"\tat com.android.dx.merge.DexMerger.merge(DexMerger.java:189)"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.command.dexer.Main.mergeLibraryDexBuffers(Main.java:454)","position":{},"original":"\tat com.android.dx.command.dexer.Main.mergeLibraryDexBuffers(Main.java:454)"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.command.dexer.Main.runMonoDex(Main.java:303)","position":{},"original":"\tat com.android.dx.command.dexer.Main.runMonoDex(Main.java:303)"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.command.dexer.Main.run(Main.java:246)","position":{},"original":"\tat com.android.dx.command.dexer.Main.run(Main.java:246)"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.command.dexer.Main.main(Main.java:215)","position":{},"original":"\tat com.android.dx.command.dexer.Main.main(Main.java:215)"}
AGPBI: {"kind":"SIMPLE","text":"\tat com.android.dx.command.Main.main(Main.java:106)","position":{},"original":"\tat com.android.dx.command.Main.main(Main.java:106)"}


 FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:dexDebug'.
> com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command '/usr/lib/jvm/java-7-oracle/bin/java'' finished with non-zero exit value 2

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

Total time: 23.247 secs

Any help on how to fix this preDexDebug error will be a great help! As a side note, I'm also not able to see my 'libs' folder in the project explorer on the left.

Answer 1

you have a jar file or a lib appearing multiple times and need to work with "configuration" in your "gradle.build"

look for how to analyze dependencies with something like:

./gradlew :app:dependencies

background on wrapper

./gradlew --info clean assembleDebug > ../myProj_build

will give you extra info in a build file that you can analyze for details on your "preDex" errors

Answer 2

You added your jar dependencies as a compile dependency. You should added it as a "provided", (see you in the README).