Android N Java8 java.time

Question

I updated to the latest Android N sdk. The only thing I don't understand is why I cannot import java.time into my code? I thought Java8 is available through Android N. Then why didn't Google add java.time package?

just waiting is an option: jack is now deprecated and java8 API will soon be supported directly: https://android-developers.googleblog.com/2017/03/future-of-java-8-language-feature.html — ccpizza, Jun 10 '17 at 06:57
@ccpizza They do not support all features of Java 8 for Android. — IgorGanapolsky, Jun 12 '17 at 13:01
Much of the java.time functionality is back-ported to Java 6 & 7 in the [*ThreeTen-Backport*](http://www.threeten.org/threetenbp/) project. Further adapted for Android in the [*ThreeTenABP*](https://stackoverflow.com/q/36000997/642706) project; see [*How to use…*](https://stackoverflow.com/q/38922754/642706). — Basil Bourque, Sep 07 '17 at 22:01

score 29 · Answer 1 · edited Jun 30 '22 at 13:10

java.time package was added only in API 26 (Android O): https://developer.android.com/reference/java/time/package-summary.html

UPDATE

Starting with version 4.0 of the Android Gradle Plugin, you can use a subset of java.time APIs (along with a number of other Java 8 language APIs) without requiring a minimum API level for your app: https://developer.android.com/studio/write/java8-support#library-desugaring

The following set of APIs are supported when building your app using Android Gradle plugin 4.0.0 or higher:

Sequential streams (java.util.stream)

A subset of java.time

java.util.function

Recent additions to java.util.{Map,Collection,Comparator}

Optionals (java.util.Optional, java.util.OptionalInt and java.util.OptionalDouble) and some other new classes useful with the above APIs

Some additions to java.util.concurrent.atomic (new methods on AtomicInteger, AtomicLong and AtomicReference)

ConcurrentHashMap (with bug fixes for Android 5.0)

To enable support for these language APIs, one needs to include the following lines build.gradle file:

android {
  defaultConfig {
    // Required when setting minSdkVersion to 20 or lower
    multiDexEnabled true
  }

  compileOptions {
    // Flag to enable support for the new language APIs
    coreLibraryDesugaringEnabled true
    // Sets Java compatibility to Java 8
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }
}

dependencies {
  coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.0.4'
}

score 21 · Accepted Answer · edited Apr 05 '17 at 19:35

21

Android N is not supporting all the features of Java 8. Following features are only supported:

Default and static interface methods
Lambda expressions
Repeatable annotations

Reflection and language-related APIs:

java.lang.FunctionalInterface
java.lang.annotation.Repeatable
java.lang.reflect.Method.isDefault()

and Reflection APIs associated with repeatable annotations, such as AnnotatedElement.getAnnotationsByType(Class)

Utility APIs:

java.util.function

For more info check the following link: http://developer.android.com/preview/j8-jack.html

edited Apr 05 '17 at 19:35

Volo

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answered Mar 16 '16 at 06:44

Maheshwar Ligade

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Thanks for the outline. I guess our only option for Java 8 Time api is https://github.com/JakeWharton/ThreeTenABP – IgorGanapolsky Mar 16 '16 at 12:38
1

@Igor right untill stable version of android-n will release. hope in stable version they will support – Maheshwar Ligade Mar 16 '16 at 12:42
Well, if they didn't add the Time api yet, then they probably won't in Android N. Otherwise, I have no idea how Google makes decisions to include or omit certain apis... – IgorGanapolsky Mar 16 '16 at 12:59
Much of the java.time functionality is back-ported to Java 6 & 7 in the [*ThreeTen-Backport*](http://www.threeten.org/threetenbp/) project. Further adapted for Android in the [*ThreeTenABP*](https://stackoverflow.com/q/36000997/642706) project; see [*How to use…*](https://stackoverflow.com/q/38922754/642706). – Basil Bourque Sep 07 '17 at 22:03

score 19 · Answer 3 · answered Feb 03 '17 at 09:43

19

There is backport library of java.time APIs for Android that can be used

https://github.com/JakeWharton/ThreeTenABP

answered Feb 03 '17 at 09:43

kotucz

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This library is no longer maintained, deprecated, and the repo is now archived. You should now [use Gradle 4.00 + desugaring](https://developer.android.com/studio/preview/features#j8-desugar) – Martin Marconcini Aug 07 '20 at 14:22

score 6 · Answer 4 · answered Aug 08 '20 at 13:37

Starting from Android Gradle Plugin 4.0.0, we can finally use proper java.time package classes without worries (almost): https://developer.android.com/studio/write/java8-support

Optional, java.time, streams, and more are desugared into Java 7 by the Android Gradle Plugin.

To add those classes support, you just need to add a few lines to your build file:

android {
  defaultConfig {
    // Required when setting minSdkVersion to 20 or lower
    multiDexEnabled true
  }

  compileOptions {
    // Flag to enable support for the new language APIs
    coreLibraryDesugaringEnabled true
    // Sets Java compatibility to Java 8
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }
}

dependencies {
  coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.0.9'
}

Here is the full list: https://developer.android.com/studio/write/java8-support-table

Kotlin still uses many Java classes underneath and, I guess, they couldn't just reimplement the java.time package in order to sustain the backwards compatibility? — Gaket, Aug 08 '20 at 18:47

Android N Java8 java.time

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