title: can't call kotlin module from java module
body: <p>I want to have an android app in java, but one library module in kotlin. However when I try to run the app in my phone, there's an error saying that it can't find my Kotlin class. This is my kotlin class:</p>
  
  <pre><code>    package com.example.mylibrary
  
      import android.util.Log
  
      class A {
          fun helloWorld(){
              Log.d("Kotlin", "Hello World!")
          }
      }
  </code></pre>
  
  <p>and gradle file for my kotlin module:</p>
  
  <pre><code>apply plugin: 'com.android.library'
  
  android {
      compileSdkVersion 23
      buildToolsVersion "23.0.1"
  
      defaultConfig {
          minSdkVersion 11
          targetSdkVersion 23
          versionCode 1
          versionName "1.0"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
      sourceSets {
          main.java.srcDirs += 'src/main/kotlin'
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      testCompile 'junit:junit:4.12'
      compile 'com.android.support:appcompat-v7:23.2.1'
      compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
  }
  buildscript {
      ext.kotlin_version = '0.6.+'
      repositories {
          mavenCentral()
      }
      dependencies {
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
      }
  }
  repositories {
      mavenCentral()
  }
  </code></pre>
  
  <p>Here's my main activity:</p>
  
  <pre><code>package com.example.uisample;
  
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  
  import com.example.mylibrary.A;
  
  public class MainActivity extends AppCompatActivity {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
          A obj = new A();
          obj.helloWorld();
  
      }
  
  }
  </code></pre>
  
  <p>Notice how android studio imports <code>com.example.mylibrary.A</code> instead of <code>com.example.mylibrar.Akt</code> as the reference says. Android studio reports no errors before compiling.</p>
  
  <p>Gradle file for app:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 23
      buildToolsVersion "23.0.1"
  
      defaultConfig {
          applicationId "com.example.uisample"
          minSdkVersion 11
          targetSdkVersion 23
          versionCode 1
          versionName "1.0"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      testCompile 'junit:junit:4.12'
      compile 'com.android.support:appcompat-v7:23.2.1'
      compile project(':mylibrary')
  }
  </code></pre>
  
  <p>After running the project, gradle throws this error: "cannot find symbol class A". What am I doing wrong?</p>