Flutter is not running?

问题:

I have some problems while running flutter in android studio

This is my error Launching lib\main.dart on Moto C Plus in debug mode... Initializing gradle... Resolving dependencies... Finished with error: Please review your Gradle project setup in the android/ folder. * Error running Gradle: Exit code 1 from: D:\FlutterPrograms\app\android\gradlew.bat app:properties: NDK is missing a "platforms" directory. If you are using NDK, verify the ndk.dir is set to a valid NDK directory. It is currently set to E:\Sdk\ndk-bundle. If you are not using NDK, unset the NDK variable from ANDROID_NDK_HOME or local.properties to remove this warning.

Project evaluation failed including an error in afterEvaluate {}. Run with --stacktrace for details of the afterEvaluate {} error.

FAILURE: Build failed with an exception.

• Where: Build file 'D:\FlutterPrograms\app\android\app\build.gradle' line: 25

• What went wrong: A problem occurred evaluating project ':app'.

  Could not resolve all artifacts for configuration 'classpath'. Could not find lint-gradle-api.jar (com.android.tools.lint:lint-gradle-api:26.1.2). Searched in the following locations: https://jcenter.bintray.com/com/android/tools/lint/lint-gradle-api/26.1.2/lint-gradle-api-26.1.2.jar

• 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 1s

This is my buid.gradle file

    buildscript {
    repositories {
        maven {
            url 'https://dl.google.com/dl/android/maven2'
        }
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
    }
}

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

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

This is my gradle error

    def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion 27

    lintOptions {
        disable 'InvalidPackage'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.shanmukh.app"
        minSdkVersion 16
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

回答1:

There were lots of similar issues raised the past days, that could be solved by adding the google() repository in first position in the repositories block of the build scripts. See detailed explanation in the following answers:

• couldn't locate lint-gradle-api-26.1.2.jar for flutter project
• Could not find play-services-basement.aar
• https://stackoverflow.com/a/52982816/6899896
• Could not find com.android.tools.build:aapt2:3.2.0

The root cause , related to missing libraries in Jcenter, is explained in detail here : https://stackoverflow.com/a/50885939/6899896

回答2:

Open the root flutter folder in your computer, and open the gradle folder in that root folder (For example C:\flutter\package\flutter_tool\gradle) and add 'google()' to the buildscript. It fixed the issue for me.

Flutter root folder:

Add 'google()' to the buildscript:

回答3:

I found a solution! Go to your flutter folder. After you need to find flutter.gradle. On my PC: C:\src\flutter\packages\flutter_tools\gradle Open flutter.gradle with note or notepad and change buildscript from this:

 repositories {
   jcenter()
    maven {
        url 'https://dl.google.com/dl/android/maven2'
    }    
}

to this:

 repositories {
    maven {
        url 'https://dl.google.com/dl/android/maven2'
    } 
    jcenter()
}