解决Android报错Dex file with version 38 cannot be used with min sdk level 29.

修改app下build.gradle文件

android {
    compileSdkVersion 29
    defaultConfig {
        applicationId "com.example.z.test1"
        minSdkVersion 29
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }降低版本我这边写成15

android {
    compileSdkVersion 29
    defaultConfig {
        applicationId "com.example.z.test1"
        minSdkVersion 15
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }