Android Studio: what compiler settings when including Google Maps

问题

I created a new project in Android Studio and added a Google Maps activity.

I get these warnings:

warning: com/google/android/gms/maps/GoogleMap.class(com/google/android/gms/maps:GoogleMap.class): major version 51 is newer than 50, the highest major version supported by this compiler.
It is recommended that the compiler be upgraded.
warning: com/google/android/gms/maps/SupportMapFragment.class(com/google/android/gms/maps:SupportMapFragment.class): major version 51 is newer than 50, the highest major version supported by this compiler.
It is recommended that the compiler be upgraded.
warning: com/google/android/gms/maps/model/LatLng.class(com/google/android/gms/maps/model:LatLng.class): major version 51 is newer than 50, the highest major version supported by this compiler.
It is recommended that the compiler be upgraded.
warning: com/google/android/gms/maps/model/MarkerOptions.class(com/google/android/gms/maps/model:MarkerOptions.class): major version 51 is newer than 50, the highest major version supported by this compiler.
It is recommended that the compiler be upgraded.
warning: com/google/android/gms/maps/model/Marker.class(com/google/android/gms/maps/model:Marker.class): major version 51 is newer than 50, the highest major version supported by this compiler.
It is recommended that the compiler be upgraded.

My guess is that I have a JDK miss-match or something. I installed JDK 7, and when I do javac -version I see 1.7.0_65. I changed in Android Studio's preferences the Project bytecode version but that didn't change these warnings.

My build.gradle has this

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    // You must install or update the Google Repository through the SDK manager to use this dependency.
    compile 'com.google.android.gms:play-services:5.0.77'
    compile 'com.android.support:support-v13:18.0.+'
}

What do I need to do to fix these warnings, or should I ignore them in Android Studio?

回答1:

"Major version" means Java version. Java 7 = 51, Java 6 = 50. The code is written for Java 7, and that is something that Android's dex supports. I am not sure what you are building with that is not set for Java 7, but that's the problem. The Maven build in the project works correctly. I don't see the error you mention, and it may be related to Java 6 vs 7 too.

回答2:

I was able to resolve this based on Jason Hocker's tip and this answer. Add this to your android gradle task:

compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_7
    targetCompatibility JavaVersion.VERSION_1_7
}

Note that you must have a Java 7 JDK installed. I also had to add this to my gradlew to allow gradle to find the correct JDK:

export JAVA_HOME=$(/usr/libexec/java_home -v 1.7)

来源：https://stackoverflow.com/questions/24807117/android-studio-what-compiler-settings-when-including-google-maps

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java

android

android-studio

java-7