blocks|key|2843068|text|作为CommonsWare+mentioned，为了参考，在你的应用程序模块(应用程序级别)的build.gradle中的android+{...}闭包中添加以下代码来解决问题：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2843069|android+{
...
++compileOptions+{
++++++++sourceCompatibility+JavaVersion.VERSION_1_8
++++++++targetCompatibility+JavaVersion.VERSION_1_8
++++}
...
}|code-block|syntax|javascript|2843070|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/q/49512629/835883^0|1P|D|2|L|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

As <a href="https://stackoverflow.com/q/49512629/835883">CommonsWare mentioned</a>, for reference add this inside the <code>android {...}</code> closure in the build.gradle for your app module (app level) to resolve the issue:
<pre><code>android {
...
 compileOptions {
 sourceCompatibility JavaVersion.VERSION_1_8
 targetCompatibility JavaVersion.VERSION_1_8
 }
...
}
</code></pre>

blocks|key|100737|text|您应该使用Java8来解决这个问题。基于the+Android+documentation，您可以通过单击菜单文件→项目结构来执行此操作。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|100738|并更改源兼容性和目标兼容性。|100739|​|100740|📷|atomic|100741|100742|您也可以直接在应用程序级别的build.gradle文件中配置它：|style|CODE|100743|android+{
++...
++//+Configure+only+for+each+module+that+uses+Java+8
++//+language+features+(either+in+its+source+code+or
++//+through+dependencies).
++compileOptions+{
++++sourceCompatibility+JavaVersion.VERSION_1_8
++++targetCompatibility+JavaVersion.VERSION_1_8
++}
}|code-block|syntax|javascript|100744|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.android.com/studio/write/java8-support#supported_features|1|IMAGE|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/e7ccda10adae2703a7da31bf4b80d36a.png|imageAlt^0|K|P|0|0|0|0|0|1|1|0|0|E|C|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@$A|19|B|1A|1|1B]]|C|$]]|$1|D|3|E|5|6|7|1C|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|1D|8|@]|9|@]|C|$]]|$1|H|3|I|5|J|7|1E|8|@]|9|@$A|1F|B|1G|1|1H]]|C|$]]|$1|K|3|G|5|6|7|1I|8|@]|9|@]|C|$]]|$1|L|3|M|5|6|7|1J|8|@$A|1K|B|1L|N|O]]|9|@]|C|$]]|$1|P|3|Q|5|R|7|1M|8|@]|9|@]|C|$S|T]]|$1|U|3|-4|5|6|7|1N|8|@]|9|@]|C|$]]]|V|$W|$5|X|Y|Z|C|$10|11]]|12|$5|13|Y|14|C|$15|16|17|-4]]]]

You should use Java 8 to solve this. Based on <a href="https://developer.android.com/studio/write/java8-support#supported_features" rel="nofollow noreferrer">the Android documentation</a>, you can do this by clicking menu File → Project Structure.
And change Source Compatibility and Target Compatibility.
<a href="https://i.stack.imgur.com/qqJo1.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qqJo1.png" alt="Enter image description here" /></a>
And you can also configure it directly in the app-level <code>build.gradle</code> file:
<pre><code>android {
 ...
 // Configure only for each module that uses Java 8
 // language features (either in its source code or
 // through dependencies).
 compileOptions {
 sourceCompatibility JavaVersion.VERSION_1_8
 targetCompatibility JavaVersion.VERSION_1_8
 }
}
</code></pre>

blocks|key|2631593|text|更新您的build.gradle(模块:应用程序)添加compileOptions块并添加JavaVersion.VERSION_1_8|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2631594|apply+plugin:+'com.android.application'

android+{
++++.................
++++.........................
++++compileOptions+{
++++++++sourceCompatibility+JavaVersion.VERSION_1_8
++++++++targetCompatibility+JavaVersion.VERSION_1_8
++++}
}|code-block|syntax|javascript|2631595|entityMap^0|R|E|19|N|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Update your build.gradle(Module:app) add <code>compileOptions</code> block and add <code>JavaVersion.VERSION_1_8</code>

<pre><code>apply plugin: 'com.android.application'

android {
 .................
 .........................
 compileOptions {
 sourceCompatibility JavaVersion.VERSION_1_8
 targetCompatibility JavaVersion.VERSION_1_8
 }
}
</code></pre>

blocks|key|100586|text|在build.gradle文件中使用以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|100587|android+{
++++compileOptions+{
++++++++incremental+true
++++++++sourceCompatibility+JavaVersion.VERSION_1_8
++++++++targetCompatibility+JavaVersion.VERSION_1_8
++++}
}|code-block|syntax|javascript|100588|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use this code in your build.gradle file:
<pre><code>android {
 compileOptions {
 incremental true
 sourceCompatibility JavaVersion.VERSION_1_8
 targetCompatibility JavaVersion.VERSION_1_8
 }
}
</code></pre>

blocks|key|98121|text|在应用程序级别的Gradle文件中，您必须编写以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|98122|android+{
...
++compileOptions+{
++++sourceCompatibility+JavaVersion.VERSION_1_8
++++targetCompatibility+JavaVersion.VERSION_1_8
++}
}|code-block|syntax|javascript|98123|它们来自安卓系统中的JavaVersion.java。|offset|length|style|BOLD|98124|98125|是Java版本的枚举。|blockquote|98126|98127|9之前：http://www.oracle.com/technetwork/java/javase/versioning-naming-139433.html|98128|9之后：http://openjdk.java.net/jeps/223|98129|entityMap|0|LINK|mutability|MUTABLE|url|http://www.oracle.com/technetwork/java/javase/versioning-naming-139433.html|1|http://openjdk.java.net/jeps/223^0|0|0|A|G|0|0|0|0|4|23|0|0|4|W|1|0^^$0|@$1|2|3|4|5|6|7|15|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|16|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|17|8|@$I|18|J|19|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|N|3|O|5|P|7|1B|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]|$1|R|3|S|5|6|7|1D|8|@]|9|@$I|1E|J|1F|1|1G]]|A|$]]|$1|T|3|U|5|6|7|1H|8|@]|9|@$I|1I|J|1J|1|1K]]|A|$]]|$1|V|3|-4|5|6|7|1L|8|@]|9|@]|A|$]]]|W|$X|$5|Y|Z|10|A|$11|12]]|13|$5|Y|Z|10|A|$11|14]]]]

In the app-level Gradle file, you have to write this code:
<pre><code>android {
...
 compileOptions {
 sourceCompatibility JavaVersion.VERSION_1_8
 targetCompatibility JavaVersion.VERSION_1_8
 }
}
</code></pre>
They come from JavaVersion.java in Android.
<blockquote>
An enumeration of Java versions.
Before 9: <a href="http://www.oracle.com/technetwork/java/javase/versioning-naming-139433.html" rel="nofollow noreferrer">http://www.oracle.com/technetwork/java/javase/versioning-naming-139433.html</a>
After 9: <a href="http://openjdk.java.net/jeps/223" rel="nofollow noreferrer">http://openjdk.java.net/jeps/223</a>
</blockquote>

blocks|key|2843135|text|这也发生在我身上，但是使用了动态特性。我已经在app模块中启用了Java+8兼容性，但我必须将此兼容性行添加到Dynamic+Feature模块中，然后它才能工作。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2843136|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

This also happened to me but using Dynamic Features. I already had Java 8 compatibility enabled in the app module but I had to add this compatibility lines to the Dynamic Feature module and then it worked.

blocks|key|2631633|text|我的项目使用ButterKnife和Retro+lambda。设置JavaVersion.VERSION_1_8将不起作用。在我找到这个Migrate+from+Retrolambda之前，它总是指责ButterKnife静态接口函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2631634|TL;DR|2631635|只需添加JavaVersion.VERSION_1_8并从项目中完全删除retrolambda即可。它将成功构建。|2631636|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.android.com/studio/write/java8-support#migrate_from_retrolambda^0|1W|O|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@$A|Q|B|R|1|S]]|C|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|U|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]]]

My project uses ButterKnife and Retro lambda. Setting JavaVersion.VERSION_1_8 will not work. It always blamed the ButterKnife static interface function until I found this <a href="https://developer.android.com/studio/write/java8-support#migrate_from_retrolambda" rel="nofollow noreferrer">Migrate from Retrolambda</a>.
TL;DR
Just add JavaVersion.VERSION_1_8 and completely remove retrolambda from your project. It will build successfully.

blocks|key|2631638|text|将minSdkVersion从19改为21为我解决了这个问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2631639|defaultConfig+{
++++applicationId+"com.example"
++++minSdkVersion+21
++++targetSdkVersion+29
++++versionCode+23
++++versionName+"1.0"
++++vectorDrawables.useSupportLibrary+=+true
}|code-block|syntax|javascript|2631640|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Changing the minSdkVersion from 19 to 21 solved the issue for me.
<pre><code>defaultConfig {
 applicationId &quot;com.example&quot;
 minSdkVersion 21
 targetSdkVersion 29
 versionCode 23
 versionName &quot;1.0&quot;
 vectorDrawables.useSupportLibrary = true
}
</code></pre>

blocks|key|98147|text|apply+plugin:+'com.android.application'
apply+plugin:+'kotlin-android'
apply+plugin:+'kotlin-android-extensions'

android+{
++++compileSdkVersion+30
++++buildToolsVersion+"30.0.0"

++++compileOptions+{
++++++++sourceCompatibility+JavaVersion.VERSION_1_8
++++++++targetCompatibility+JavaVersion.VERSION_1_8
++++}

++++defaultConfig+{
++++++++applicationId+"com.example.architecture"
++++++++minSdkVersion+16
++++++++targetSdkVersion+30
++++++++versionCode+1
++++++++versionName+"1.0"

++++++++testInstrumentationRunner+"androidx.test.runner.AndroidJUnitRunner"
++++}

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

dependencies+{
++++implementation+'androidx.room:room-runtime:2.2.5'
++++implementation+'androidx.lifecycle:lifecycle-extensions:2.2.0'
++++annotationProcessor+'androidx.room:room-compiler:2.2.5'
++++def+lifecycle_version+=+"2.2.0"
++++def+arch_version+=+"2.1.0"

++++implementation+fileTree(dir:+"libs",+include:+["*.jar"])
++++implementation+"org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
++++implementation+'androidx.core:core-ktx:1.3.0'
++++implementation+'androidx.appcompat:appcompat:1.1.0'
++++implementation+'androidx.constraintlayout:constraintlayout:1.1.3'
++++testImplementation+'junit:junit:4.12'
++++androidTestImplementation+'androidx.test.ext:junit:1.1.1'
++++androidTestImplementation+'androidx.test.espresso:espresso-core:3.2.0'
++++implementation+"androidx.lifecycle:lifecycle-viewmodel-savedstate:$lifecycle_version"
++++implementation+"androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"
++++implementation+"androidx.lifecycle:lifecycle-service:$lifecycle_version"
++++implementation+"androidx.lifecycle:lifecycle-process:$lifecycle_version"
++++implementation+"androidx.cardview:cardview:1.0.0"
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|98148|unstyled|98149|在应用程序模块的build.gradle中添加配置|offset|length|style|BOLD|CODE|98150|android+{
++++...
++++compileOptions+{
++++++++sourceCompatibility+JavaVersion.VERSION_1_8
++++++++targetCompatibility+JavaVersion.VERSION_1_8
++++}
}|98151|entityMap^0|0|0|1|4|8|C|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|R|8|@]|9|@]|A|$]]|$1|F|3|G|5|E|7|S|8|@$H|T|I|U|J|K]|$H|V|I|W|J|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$B|C]]|$1|O|3|-4|5|E|7|Y|8|@]|9|@]|A|$]]]|P|$]]

<pre><code>apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
 compileSdkVersion 30
 buildToolsVersion &quot;30.0.0&quot;

 compileOptions {
 sourceCompatibility JavaVersion.VERSION_1_8
 targetCompatibility JavaVersion.VERSION_1_8
 }

 defaultConfig {
 applicationId &quot;com.example.architecture&quot;
 minSdkVersion 16
 targetSdkVersion 30
 versionCode 1
 versionName &quot;1.0&quot;

 testInstrumentationRunner &quot;androidx.test.runner.AndroidJUnitRunner&quot;
 }

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

dependencies {
 implementation 'androidx.room:room-runtime:2.2.5'
 implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
 annotationProcessor 'androidx.room:room-compiler:2.2.5'
 def lifecycle_version = &quot;2.2.0&quot;
 def arch_version = &quot;2.1.0&quot;

 implementation fileTree(dir: &quot;libs&quot;, include: [&quot;*.jar&quot;])
 implementation &quot;org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version&quot;
 implementation 'androidx.core:core-ktx:1.3.0'
 implementation 'androidx.appcompat:appcompat:1.1.0'
 implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
 testImplementation 'junit:junit:4.12'
 androidTestImplementation 'androidx.test.ext:junit:1.1.1'
 androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
 implementation &quot;androidx.lifecycle:lifecycle-viewmodel-savedstate:$lifecycle_version&quot;
 implementation &quot;androidx.lifecycle:lifecycle-common-java8:$lifecycle_version&quot;
 implementation &quot;androidx.lifecycle:lifecycle-service:$lifecycle_version&quot;
 implementation &quot;androidx.lifecycle:lifecycle-process:$lifecycle_version&quot;
 implementation &quot;androidx.cardview:cardview:1.0.0&quot;
}
</code></pre>
<hr />
Add the configuration in your app module's <code>build.gradle</code>
<pre><code>android {
 ...
 compileOptions {
 sourceCompatibility JavaVersion.VERSION_1_8
 targetCompatibility JavaVersion.VERSION_1_8
 }
}
</code></pre>

I upgraded to Android Studio 3.1 and I'm getting the following error:
<blockquote>
Default interface methods are only supported starting with Android N (--min-api 24): void android.arch.lifecycle.DefaultLifecycleObserver.onCreate(android.arch.lifecycle.LifecycleOwner) 
 
Message{kind=ERROR, text=Default interface methods are only supported starting with Android N (--min-api 24): void android.arch.lifecycle.DefaultLifecycleObserver.onCreate(android.arch.lifecycle.LifecycleOwner), sources=[Unknown source file], tool name=Optional.of(D8)}
</blockquote>
<a href="https://i.stack.imgur.com/Nof2r.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Nof2r.png" alt="Error" /></a>
Here is my Gradle configuration:
<pre><code>compileSdkVersion 27
//buildToolsVersion '27.0.3'
defaultConfig {
 minSdkVersion 16
 targetSdkVersion 27
 multiDexEnabled true
 //...
 }
</code></pre>
As you can see, I am targeting 27 which is already ahead of 24 that it's complaining about. What exactly should I do to fix this? If I change to 1.8 Java, won't I be missing a lot of customers? Why was I not getting this error before I upgraded Android Studio?
I do not know if this is about the LifecycleObserver class I recently put in. It was in Kotlin and now I changed it to Java, but I still get the same error after cleaning the project:
<pre class="lang-java prettyprint-override"><code>public class LifeCycleAwareObserver implements LifecycleObserver {

 @OnLifecycleEvent(Lifecycle.Event.ON_STOP)
 public void onAppBackgrounded() {
 AnalyticsUtils.trackStartSession(true);
 }

 @OnLifecycleEvent(Lifecycle.Event.ON_START)
 public void onAppForegrounded() {
 AnalyticsUtils.trackStartSession(false);
 }
}
</code></pre>
How can I trace where the error is coming from so I can fix it?
Here are my version dependencies:
<pre><code>project.ext {

 firebase_version = '12.0.0'

 supportlib_version = '27.0.2'

 room_version = '1.0.0'

 espresso_version = '3.0.1'

 archLifecycleVersion = '1.1.1'
 }
</code></pre>

Default interface methods are only supported starting with Android 7.0 (Nougat)

Android Studio

Android

Kotlin

Java

我升级到Android Studio 3.1，得到以下错误：只支持Android N开头的工具默认接口方法(--  -api 24)：void android.arch.lifecycle.DefaultLifecycleObserver.onCreate(android.arch.lifecycle.Lifecycl...

问仅从Android 7.0 (Nougat)开始支持默认接口方法
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