Execution failed for task ‘:app:preDebugBuild’.

Android dependency ‘androidx.core:core’ has different version for the compile (1.0.0) and runtime (1.0.1) classpath. You should manually set the same version via DependencyResolution

Android代码使用Android.support库来确保向后兼容性老版本。目前support库已经停止维护，并替换为AndroidX，AndroidX具有与旧库想通过的功能和一些附加功能，但这两套库是不兼容的，所以会报错。未来都会为AndroidX为主，Android Support Library已经不再建议使用，并会慢慢停止维护。另外，从Android Studio 3.4.2开始，新建的项目已经强制勾选使用AndroidX架构了。

Launching lib/main.dart on Redmi Note 7 Pro in debug mode...
Initializing gradle...
Resolving dependencies...
Running Gradle task 'assembleDebug'...

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:preDebugBuild'.
> Android dependency 'androidx.core:core' has different version for the compile (1.0.0) and runtime (1.0.1) classpath. You should manually set the same version via DependencyResolution

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 6s
Finished with error: Gradle task assembleDebug failed with exit code 1

解决办法

目前网上主要有两种解决办法，第一种就是规避使用AndroidX的插件，避免使用AndroidX，显然这将做出很大的妥协，绝对不是最好的方式。另一种就是集成AndroidX，这种方式其实也不简单，我第一次通过AS去做的时候就不知道为什么没有成功，手动的话又很麻烦，还容易出错，这也许不太适合较大的老项目。
针对我的问题我找到了解决办法，在项目级build.gradle文件中增加下面的代码块便能解决问题

subprojects {
        project.configurations.all {
            resolutionStrategy.eachDependency { details ->
                if (details.requested.group == 'com.android.support'
                        && !details.requested.name.contains('multidex') ) {
                    details.useVersion "27.1.1"
                }
                if (details.requested.group == 'androidx.core'
                        && !details.requested.name.contains('androidx') ) {
                    details.useVersion "1.0.1"
                }
               }
            }
        }
    }

完整的build.gradle代码

buildscript {
    ext.kotlin_version = '1.3.0'
   repositories {
//        google()
//        jcenter()
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
       google()
   }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.2.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }

    subprojects {
        project.configurations.all {
            resolutionStrategy.eachDependency { details ->
                if (details.requested.group == 'com.android.support'
                        && !details.requested.name.contains('multidex') ) {
                    details.useVersion "27.1.1"
                }
                if (details.requested.group == 'androidx.core'
                        && !details.requested.name.contains('androidx') ) {
                    details.useVersion "1.0.2"
                }
                if (details.requested.group == 'androidx.appcompat'
                        && !details.requested.name.contains('androidx') ) {
                    details.useVersion "1.0.2"
                }
            }
        }
    }
}

allprojects {
    repositories {
//        google()
//        jcenter()
        maven { url 'https://maven.aliyun.com/repository/google' }
        maven { url 'https://maven.aliyun.com/repository/jcenter' }
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public' }
    }
}

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}