Unable to import in Android Studio

[mcondarelli]

Apparently some incompatibility is again afoot.

I am compiling with:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "it.condarelli.okcash"
        minSdkVersion 26
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:design:28.0.0'
    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'
    // mcon
    implementation 'com.github.kenglxn.QRGen:android:2.5.0'
    implementation 'com.koushikdutta.async:androidasync:2.2.1'
}

but the line:

import com.koushikdutta.async.http.server.AsyncHttpServer;

(and similar variations) gives error: Cannot resolve symbol 'AsyncHttpServer'.

Any help appreciated.

[huayicheng2015]

我认为你的Android Studio没有sync project成功，导致没有正常下载到相关jar包。