降低編譯版本報錯

由於項目需要降低編譯版本的

1. project structure

2. 修改
   app build.gradle :
   各種版本號
   project build.gradle :
   classpath ‘com.android.tools.build:gradle:2.3.0’

3. 修改依賴

//    implementation fileTree(dir: 'libs', include: ['*.jar'])
//    implementation 'androidx.appcompat:appcompat:1.1.0'
//    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
//    testImplementation 'junit:junit:4.12'
//    androidTestImplementation 'androidx.test:runner:1.2.0'
//    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
//    implementation 'com.google.code.gson:gson:2.8.2'

    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.2.0'
    testCompile 'junit:junit:4.12'