“程序类型已经存在"是什么?意思是? [英] What does "Program type already present" mean?

问题描述

我正在尝试在Android Studio中构建应用.将Eclipse Paho库添加为gradle依赖项(或者是Maven?我是Android生态系统的新手)之后，出现以下错误:

I'm trying to build an app in Android Studio. After adding the Eclipse Paho library as a gradle dependency(or is it Maven? I'm new to the Android ecosystem), I got the following error:

Program type already present: android.support.v4.accessibilityservice.AccessibilityServiceInfoCompat
Message{kind=ERROR, text=Program type already present: android.support.v4.accessibilityservice.AccessibilityServiceInfoCompat, sources=[Unknown source file], tool name=Optional.of(D8)}

我检查了许多与此错误有关的StackOverflow问题，但是答案都是特定于某些库的. 我不仅在寻找错误的解决方案，而且还在寻找错误的含义 .这样，人们可以更轻松地找到解决方案他们的具体情况.到目前为止，还没有答案.

I've checked many different StackOverflow questions relating to this error, but the answers are all specific to certain libraries. I'm looking not only for a solution to the error, but an understanding of what the error means. That way it'll be easier for people to figure out solutions for their specific cases. So far, no answer has provided that.

从其他StackOverflow答案来看，我发现它与gradle文件有关.因此，这是app/build.gradle:

From other StackOverflow answers, I've gathered that it has something to do with my gradle file. So, here's app/build.gradle:

apply plugin: 'com.android.application'
android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "---REDACTED FOR PRIVACY---"
        minSdkVersion 15
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:appcompat-v7:27.1.0'
    implementation 'com.android.support:support-media-compat:27.1.0'
    implementation 'com.android.support:support-v13:27.1.0'
    implementation 'com.google.android.gms:play-services-maps:12.0.1'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.0.2'
    implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.0.2'
}

repositories {
    maven { url 'https://repo.eclipse.org/content/repositories/paho-releases/' }
} 

推荐答案

此问题通常是由于命名冲突(在您的情况下为support-v4库)引起的，该库由多个库使用.

This problem usually come from a naming conflict, in your case the support-v4 library, which is use by several libraries.

要找到模块app(应用程序的默认模块名称)的依赖关系列表，我们可以执行gradlew app:dependencies来检索所有库的列表.

To find the list of dependencies for the module app (default module's name for the app) we can do a gradlew app:dependencies to retrieve a list of all the libraries.

我们发现support-v4被以下人员使用:

We found that support-v4 is used by:

//short version of the dependencies list highlighting support-v4
+--- com.android.support:support-v13:27.1.0
|    \--- com.android.support:support-v4:27.1.0

+--- com.google.android.gms:play-services-maps:12.0.1
|    +--- com.google.android.gms:play-services-base:12.0.1
|    |    +--- com.google.android.gms:play-services-basement:12.0.1
|    |    |    +--- com.android.support:support-v4:26.1.0 -> 27.1.0 (*)

+--- org.eclipse.paho:org.eclipse.paho.android.service:1.0.2
|    +--- com.google.android:support-v4:r7  // <- problem here

我们看到Maps上的support-v4将使用support-v13提供的版本.

We see that the support-v4 on Maps will use the version provided from support-v13.

我们还看到eclipse库正在使用另一个版本(r7 ??).

We also see that the eclipse library is using another version (r7 ??).

要解决您的问题，您可以尝试从以下Eclipse库中排除模块support-v4:

To resolve your issue, you can try to exclude the module support-v4 from this eclipse library like this:

implementation ('org.eclipse.paho:org.eclipse.paho.android.service:1.0.2') {
    exclude module: 'support-v4'
}

那么您应该能够编译您的应用程序.

Then you should be able to compile your application.

请注意，通过测试代码，eclipse模块不会损坏.

Btw you should take care that the eclipse module won't break by testing your code.

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