Installation failed with Android Studio, APK not signed

Question

Recently change to Android Studio from Eclipse and I have also changed the JDK from java-open-jdk to jdk1.7.0_45.

Now I'm trying to run my first app and I get this message:

Installation failed since the APK was either not signed, or signed incorrectly.
If this is a Gradle-based project, then make sure the signing configuration 
is specified in the Gradle build script

Edit:

When I'm running from Android Studio I get the error displayed above. When I'm running it from the command line I don't get an error (well the app is running and I get an error but nothing to do with gradle).

I got the code from here

You can check build.gradle here at google repo

UPDATE 2:

I added this code

signingConfigs {
    release {
        storeFile file("john.keystore")
        storePassword "john"
        keyAlias "johnkeystore"
        keyPassword "john"
    }
}

just above the buildTypes code block in the build.gradle file. File john.keystore is on the root of my Project. I'm running gradlew assembleRelease and I'm getting a xxx-release-unsigned.apk.

Answer 1

If you indeed runing build with gradle you need to configure signingConfigs. Android can configure your debug signingConfig automatically. You can make release signingConfig in a next manner:

android {

    signingConfigs {

        release {

            storeFile file('android.keystore')
            storePassword "pwd"
            keyAlias "alias"
            keyPassword "pwd"
        }
    }

    buildTypes {

       release {

           signingConfig signingConfigs.release
       }
    }
}

Check manual on this topic here: http://tools.android.com/tech-docs/new-build-system/user-guide#TOC-Signing-Configurations

If you still have issues, please update question with your build.gradle. Most likely issue is laying here. I'm using JDK 1.7 and gradle builds are working fine.