android - 无法解析 ':app@debug/compileClasspath' : Could not resolve androidx 的依赖关系

Question

我正在开发 Android 应用程序，它的项目太大了，有很多类，但今天我正在尝试创建一个新类，然后我得到了这段代码:

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

    public class Main2Activity extends AppCompatActivity {

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main2);
        }
    }

你可以看到这一行:

导入androidx.appcompat.app.AppCompatActivity;

appcompat 是红色的

虽然旧的类都有这一行:

导入android.support.v7.app.AppCompatActivity;

和这样的 xml 代码:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Main2Activity">

</androidx.constraintlayout.widget.ConstraintLayout>

你也可以看到androidx我试图删除该类并再次创建它并尝试创建新的 fragment 而不是类但都是用 x 创建的

几天前我将库从 27 更新到 28 我不知道这是否会导致这个问题现在我无法同步项目我只是遇到了这些错误:

Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve androidx.constraintlayout:constraintlayout:1.1.2. Open File Show Details

Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not resolve androidx.constraintlayout:constraintlayout:1.1.2. Open-File Show Details

这是应用程序 gradle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    buildToolsVersion "27.0.3"
    defaultConfig {
        applicationId "giga.net.world.GN"
        minSdkVersion 16
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        aaptOptions {
            cruncherEnabled = false
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.constraintlayout:constraintlayout:1.1.2'
    androidTestImplementation('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })

    implementation 'com.android.support:appcompat-v7:28.0.0-alpha1'
    implementation 'com.android.support:design:28.0.0-alpha1'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    implementation 'com.android.support:cardview-v7:28.0.0-alpha1'
    implementation 'com.android.support:recyclerview-v7:28.0.0-alpha1'
    implementation 'com.squareup.picasso:picasso:2.71828'
    implementation 'com.jakewharton:butterknife:8.8.1'
    implementation 'com.roughike:bottom-bar:2.0.2'
    implementation 'com.android.support:palette-v7:28.0.0-alpha1'
    implementation 'com.android.support:support-v4:28.0.0-alpha1'
    testImplementation 'junit:junit:4.12'
    annotationProcessor 'com.jakewharton:butterknife-compiler:8.8.1'
    implementation 'com.android.support:support-core-utils:28.0.0-alpha1'
    implementation 'net.alexandroid.utils:mylog:1.1'
    implementation 'com.google.android.exoplayer:exoplayer:r1.5.16'
    implementation project(':playercontrolview')
}

和项目gradle:

buildscript {
    repositories {
        jcenter()
        mavenCentral()
        google()
        maven {
            url "https://maven.google.com"
        }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.3.0-alpha02'
        classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.8.0'
        classpath 'com.github.dcendents:android-maven-gradle-plugin:1.4.1'
        classpath 'com.novoda:bintray-release:0.5.0'
//        classpath 'com.google.gms:google-services:3.0.0'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
        mavenCentral()
        google()
        maven {
            url "https://maven.google.com"
        }
    }
}

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

还有一个包含主要项目的库项目，它的 gradle 是:

apply plugin: 'com.android.library'
apply plugin: 'com.novoda.bintray-release'

android {
    compileSdkVersion 27
    buildToolsVersion "27.0.3"

    defaultConfig {
        minSdkVersion 16
        targetSdkVersion 27
        versionCode 1
        versionName "1.0.1"
    }

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

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    testImplementation 'junit:junit:4.12'
    implementation 'com.android.support:appcompat-v7:27.1.1'
}

publish {
    userOrg = 'ogapants'
    groupId = 'com.github.ogapants.playercontrolview'
    artifactId = 'playercontrolview'
    publishVersion = '1.0.1'
    desc = 'This library provides easily customizable MediaController for Android'
    website = 'https://github.com/ogapants/PlayerControlView'
    licences = ['Apache-2.0']
}

当我删除新创建的类或 fragment 并再次同步项目时，错误消失，一切恢复正常项目怎么了？

Answer 1

constraintLayout 有 2 个依赖项。删除其中一个。使用实现 'androidx.constraintlayout:constraintlayout:1.1.2'或者 实现 'com.android.support.constraint:constraint-layout:1.0.2'