默认格式下生成project，编译出现
Program type already present: android.support.v4.app.backstackrecord$Op
//TODO other...
compileSdkVersion 28
defaultConfig {
applicationId "com.changan.facein"
minSdkVersion 19
targetSdkVersion 28
versionCode 1
versionName "v1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
//TODO other...
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:28.0.0-alpha3'
implementation 'com.android.support.constraint:constraint-layout:1.1.2'
implementation 'com.android.support:design:28.0.0-alpha3'
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'
}
后来去查阅Google官网和论坛，发现只要把API等级从28改成27以下就可以完美解决。代码如下
//TODO other...
compileSdkVersion 27
defaultConfig {
applicationId "com.changan.facein"
minSdkVersion 19
targetSdkVersion 27
versionCode 1
versionName "v1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
//TODO other...
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:27.1.1'
implementation 'com.android.support.constraint:constraint-layout:1.1.2'
implementation 'com.android.support:design:27.1.1'
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'
}
作为一个作死的程序员，一定要搞懂为嘛会出现这个情况。然后再查阅一批资料和跟大神不断交流中得出，
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
这两兄弟最多支持到API27，到28跑不过人家了，然后这里就得出另一个解决方案，把这两兄弟的版本提升也是可以的。然而Maven大佬告诉我，他还没有最新的，好吧，楼上的方案还是暂行可以的
MAVEN runner
MAVEN espresso-core
