Gradle sync failed: Could not find method android() for arguments

Gradle sync failed: Could not find method android() for arguments [build_645ygzrgp6ae4ps0o5libuz2s$_run_closure2@6ddfd772] on root project 'MultiModule'.

Consult IDE log for more details (Help | Show Log)

以下是我当时报错时的 项目 build.gradle 文件内容：

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.2.3'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}
allprojects {
    repositories {
        jcenter()
    }
}

android {
    compileSdkVersion 21
    buildToolsVersion '25.0.2'
    defaultConfig {
        minSdkVersion 21
        targetSdkVersion 21
    }
    productFlavors {
    }
}
dependencies {
}

---

原因：

根目录下的 build.gradle 文件不能包含 android 区块。

android 区块只能包含在 模块中的 build.gradle文件中。

apply plugin: 'com.android.library'

android {
    compileSdkVersion 21
    buildToolsVersion '25.0.2'
    defaultConfig {
        minSdkVersion 21
        targetSdkVersion 21
    }
}