Rewrite to Kotlin

build.gradle

 buildscript {
+    ext.kotlin_version = '1.1.3'
+
     repositories {
         jcenter()
     }
 
     dependencies {
         classpath 'com.android.tools.build:gradle:2.3.1'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
 
-allprojects {
-    repositories {
-        jcenter()
-        maven {
-            url 'http://oss.sonatype.org/content/repositories/snapshots'
-        }
-    }
+repositories {
+    jcenter()
 }
 
 apply plugin: 'com.android.library'
-
+apply plugin: 'kotlin-android'
 
 android {
     compileSdkVersion 26
@@ -50,9 +48,10 @@ android {
 }
 
 dependencies {
-    compile 'org.apache.commons:commons-lang3:3.5'
+    compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
+
+    compile 'org.apache.commons:commons-text:1.1'
     compile 'commons-io:commons-io:2.5'
-    provided 'org.projectlombok:lombok:1.16.16'
 
     // ez-vcard to parse/generate VCards
     compile('com.googlecode.ez-vcard:ez-vcard:0.10.2') {
@@ -66,8 +65,10 @@ dependencies {
     androidTestCompile 'com.android.support.test:runner:+'
     androidTestCompile 'com.android.support.test:rules:+'
     androidTestCompile 'junit:junit:4.12'
+    androidTestCompile 'org.projectlombok:lombok:1.16.16'
 
     testCompile 'junit:junit:4.12'
+    testCompile 'org.projectlombok:lombok:1.16.16'
 }
 
 // grant permissions for unit tests

src/androidTest/java/at/bitfire/vcard4android/AndroidAddressBookTest.java

@@ -21,6 +21,8 @@ import org.junit.Test;
 
 import java.util.Arrays;
 
+import at.bitfire.vcard4android.impl.TestAddressBook;
+
 import static android.support.test.InstrumentationRegistry.getContext;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -47,7 +49,7 @@ public class AndroidAddressBookTest {
 
     @Test
 	public void testSettings() throws ContactsStorageException {
-		AndroidAddressBook addressBook = new AndroidAddressBook(testAccount, provider, AndroidGroupFactory.INSTANCE, AndroidContactFactory.INSTANCE);
+		AndroidAddressBook addressBook = new TestAddressBook(testAccount, provider);
 
 		ContentValues values = new ContentValues();
 		values.put(ContactsContract.Settings.SHOULD_SYNC, false);
@@ -68,7 +70,7 @@ public class AndroidAddressBookTest {
 
     @Test
     public void testSyncState() throws ContactsStorageException {
-		AndroidAddressBook addressBook = new AndroidAddressBook(testAccount, provider, AndroidGroupFactory.INSTANCE, AndroidContactFactory.INSTANCE);
+		AndroidAddressBook addressBook = new TestAddressBook(testAccount, provider);
 
 		addressBook.setSyncState(new byte[0]);
 		assertEquals(0, addressBook.getSyncState().length);

src/androidTest/java/at/bitfire/vcard4android/AndroidContactTest.java

@@ -26,7 +26,9 @@ import java.io.IOException;
 import java.nio.charset.Charset;
 import java.sql.Date;
 import java.util.Arrays;
+import java.util.List;
 
+import at.bitfire.vcard4android.impl.TestAddressBook;
 import ezvcard.VCardVersion;
 import ezvcard.property.Address;
 import ezvcard.property.Birthday;
@@ -52,7 +54,7 @@ public class AndroidContactTest {
         provider = getContext().getContentResolver().acquireContentProviderClient(ContactsContract.AUTHORITY);
         assertNotNull(provider);
 
-        addressBook = new AndroidAddressBook(testAccount, provider, AndroidGroupFactory.INSTANCE, AndroidContactFactory.INSTANCE);
+        addressBook = new TestAddressBook(testAccount, provider);
     }
 
     @After
@@ -64,30 +66,30 @@ public class AndroidContactTest {
     @Test
     public void testAddAndReadContact() throws ContactsStorageException, FileNotFoundException {
         Contact vcard = new Contact();
-        vcard.displayName = "Mya Contact";
-        vcard.prefix = "Magª";
-        vcard.givenName = "Mya";
-        vcard.familyName = "Contact";
-        vcard.suffix = "BSc";
-        vcard.phoneticGivenName = "Först";
-        vcard.phoneticMiddleName = "Mittelerde";
-        vcard.phoneticFamilyName = "Fämilie";
-        vcard.birthDay = new Birthday(Date.valueOf("1980-04-16"));
+        vcard.setDisplayName("Mya Contact");
+        vcard.setPrefix("Magª");
+        vcard.setGivenName("Mya");
+        vcard.setFamilyName("Contact");
+        vcard.setSuffix("BSc");
+        vcard.setPhoneticGivenName("Först");
+        vcard.setPhoneticMiddleName("Mittelerde");
+        vcard.setPhoneticFamilyName("Fämilie");
+        vcard.setBirthDay(new Birthday(Date.valueOf("1980-04-16")));
 
         AndroidContact contact = new AndroidContact(addressBook, vcard, null, null);
         contact.create();
 
-        @Cleanup("delete") AndroidContact contact2 = new AndroidContact(addressBook, contact.id, null, null);
+        @Cleanup("delete") AndroidContact contact2 = new AndroidContact(addressBook, contact.getId(), null, null);
         Contact vcard2 = contact2.getContact();
-        assertEquals(vcard.displayName, vcard2.displayName);
-        assertEquals(vcard.prefix, vcard2.prefix);
-        assertEquals(vcard.givenName, vcard2.givenName);
-        assertEquals(vcard.familyName, vcard2.familyName);
-        assertEquals(vcard.suffix, vcard2.suffix);
-        assertEquals(vcard.phoneticGivenName, vcard2.phoneticGivenName);
-        assertEquals(vcard.phoneticMiddleName, vcard2.phoneticMiddleName);
-        assertEquals(vcard.phoneticFamilyName, vcard2.phoneticFamilyName);
-        assertEquals(vcard.birthDay, vcard2.birthDay);
+        assertEquals(vcard.getDisplayName(), vcard2.getDisplayName());
+        assertEquals(vcard.getPrefix(), vcard2.getPrefix());
+        assertEquals(vcard.getGivenName(), vcard2.getGivenName());
+        assertEquals(vcard.getFamilyName(), vcard2.getFamilyName());
+        assertEquals(vcard.getSuffix(), vcard2.getSuffix());
+        assertEquals(vcard.getPhoneticGivenName(), vcard2.getPhoneticGivenName());
+        assertEquals(vcard.getPhoneticMiddleName(), vcard2.getPhoneticMiddleName());
+        assertEquals(vcard.getPhoneticFamilyName(), vcard2.getPhoneticFamilyName());
+        assertEquals(vcard.getBirthDay(), vcard2.getBirthDay());
     }
 
     @Test
@@ -99,37 +101,37 @@ public class AndroidContactTest {
                 "TEL;CELL=;PREF=:+12345\r\n" +
                 "EMAIL;PREF=invalid:test@example.com\r\n" +
                 "END:VCARD\r\n";
-        Contact[] contacts = Contact.fromStream(IOUtils.toInputStream(vCard, charset), charset, null);
+        List<Contact> contacts = Contact.fromStream(IOUtils.toInputStream(vCard, charset), charset, null);
 
-        AndroidContact dbContact = new AndroidContact(addressBook, contacts[0], null, null);
+        AndroidContact dbContact = new AndroidContact(addressBook, contacts.get(0), null, null);
         dbContact.create();
 
-        @Cleanup("delete") AndroidContact dbContact2 = new AndroidContact(addressBook, dbContact.id, null, null);
+        @Cleanup("delete") AndroidContact dbContact2 = new AndroidContact(addressBook, dbContact.getId(), null, null);
         Contact contact2 = dbContact2.getContact();
-        assertEquals("Test", contact2.displayName);
-        assertEquals("+12345", contact2.phoneNumbers.get(0).property.getText());
-        assertEquals("test@example.com", contact2.emails.get(0).property.getValue());
+        assertEquals("Test", contact2.getDisplayName());
+        assertEquals("+12345", contact2.getPhoneNumbers().get(0).getProperty().getText());
+        assertEquals("test@example.com", contact2.getEmails().get(0).getProperty().getValue());
     }
 
     @Test
     public void testLargeTransactionManyRows() throws ContactsStorageException, FileNotFoundException {
         Contact vcard = new Contact();
-        vcard.displayName = "Large Transaction (many rows)";
+        vcard.setDisplayName("Large Transaction (many rows)");
         for (int i = 0; i < 4000; i++)
-            vcard.emails.add(new LabeledProperty<Email>(new Email("test" + i + "@example.com")));
+            vcard.getEmails().add(new LabeledProperty<Email>(new Email("test" + i + "@example.com")));
 
         AndroidContact contact = new AndroidContact(addressBook, vcard, null, null);
         contact.create();
 
-        @Cleanup("delete") AndroidContact contact2 = new AndroidContact(addressBook, contact.id, null, null);
+        @Cleanup("delete") AndroidContact contact2 = new AndroidContact(addressBook, contact.getId(), null, null);
         Contact vcard2 = contact2.getContact();
-        assertEquals(4000, vcard2.emails.size());
+        assertEquals(4000, vcard2.getEmails().size());
     }
 
     @Test(expected = ContactsStorageException.class)
     public void testLargeTransactionSingleRow() throws ContactsStorageException {
         Contact vcard = new Contact();
-        vcard.displayName = "Large Transaction (one row which is too large)";
+        vcard.setDisplayName("Large Transaction (one row which is too large)");
 
         // 1 MB eTag ... have fun
         char data[] = new char[1024*1024];
@@ -146,7 +148,7 @@ public class AndroidContactTest {
         address.setLabel("My \"Label\"\nLine 2");
         address.setStreetAddress("Street \"Address\"");
         Contact contact = new Contact();
-        contact.addresses.add(new LabeledProperty<>(address));
+        contact.getAddresses().add(new LabeledProperty<>(address));
 
         /* label-param = "LABEL=" param-value
          * param-values must not contain DQUOTE and should be encoded as defined in RFC 6868
@@ -171,16 +173,16 @@ public class AndroidContactTest {
     @Test
     public void testBirthdayWithoutYear() throws ContactsStorageException, FileNotFoundException {
         Contact vcard = new Contact();
-        vcard.displayName = "Mya Contact";
-        vcard.birthDay = new Birthday(PartialDate.parse("-04-16"));
+        vcard.setDisplayName("Mya Contact");
+        vcard.setBirthDay(new Birthday(PartialDate.parse("-04-16")));
 
         AndroidContact contact = new AndroidContact(addressBook, vcard, null, null);
         contact.create();
 
-        @Cleanup("delete") AndroidContact contact2 = new AndroidContact(addressBook, contact.id, null, null);
+        @Cleanup("delete") AndroidContact contact2 = new AndroidContact(addressBook, contact.getId(), null, null);
         Contact vcard2 = contact2.getContact();
-        assertEquals(vcard.displayName, vcard2.displayName);
-        assertEquals(vcard.birthDay, vcard2.birthDay);
+        assertEquals(vcard.getDisplayName(), vcard2.getDisplayName());
+        assertEquals(vcard.getBirthDay(), vcard2.getBirthDay());
     }
 
 

src/androidTest/java/at/bitfire/vcard4android/AndroidGroupTest.java

@@ -19,6 +19,9 @@ import org.junit.Before;
 import org.junit.Test;
 
 import java.io.FileNotFoundException;
+import java.util.List;
+
+import at.bitfire.vcard4android.impl.TestAddressBook;
 
 import static android.support.test.InstrumentationRegistry.getContext;
 import static org.junit.Assert.assertEquals;
@@ -37,7 +40,7 @@ public class AndroidGroupTest {
         provider = getContext().getContentResolver().acquireContentProviderClient(ContactsContract.AUTHORITY);
         assertNotNull(provider);
 
-        addressBook = new AndroidAddressBook(testAccount, provider, AndroidGroupFactory.INSTANCE, AndroidContactFactory.INSTANCE);
+        addressBook = new TestAddressBook(testAccount, provider);
     }
 
     @After
@@ -49,24 +52,24 @@ public class AndroidGroupTest {
     @Test
     public void testCreateReadDeleteGroup() throws FileNotFoundException, ContactsStorageException {
         Contact contact = new Contact();
-        contact.displayName = "at.bitfire.vcard4android-AndroidGroupTest";
-        contact.note = "(test group)";
+        contact.setDisplayName("at.bitfire.vcard4android-AndroidGroupTest");
+        contact.setNote("(test group)");
 
         // ensure we start without this group
-        assertEquals(0, addressBook.queryGroups(ContactsContract.Groups.TITLE + "=?", new String[] { contact.displayName }).length);
+        assertEquals(0, addressBook.queryGroups(ContactsContract.Groups.TITLE + "=?", new String[] { contact.getDisplayName() }).size());
 
         // create group
         AndroidGroup group = new AndroidGroup(addressBook, contact, null, null);
         group.create();
-        AndroidGroup[] groups = addressBook.queryGroups(ContactsContract.Groups.TITLE + "=?", new String[] { contact.displayName } );
-        assertEquals(1, groups.length);
-        Contact contact2 = groups[0].getContact();
-        assertEquals(contact.displayName, contact2.displayName);
-        assertEquals(contact.note, contact2.note);
+        List<AndroidGroup> groups = addressBook.queryGroups(ContactsContract.Groups.TITLE + "=?", new String[] { contact.getDisplayName() } );
+        assertEquals(1, groups.size());
+        Contact contact2 = groups.get(0).getContact();
+        assertEquals(contact.getDisplayName(), contact2.getDisplayName());
+        assertEquals(contact.getNote(), contact2.getNote());
 
         // delete group
         group.delete();
-        assertEquals(0, addressBook.queryGroups(ContactsContract.Groups.TITLE + "=?", new String[] { contact.displayName }).length);
+        assertEquals(0, addressBook.queryGroups(ContactsContract.Groups.TITLE + "=?", new String[] { contact.getDisplayName() }).size());
     }
 
 }

src/androidTest/java/at/bitfire/vcard4android/impl/TestAddressBook.kt

+/*
+ * Copyright © Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.vcard4android.impl
+
+import android.accounts.Account
+import android.content.ContentProviderClient
+import at.bitfire.vcard4android.*
+
+class TestAddressBook(
+        account: Account,
+        provider: ContentProviderClient
+): AndroidAddressBook<AndroidContact, AndroidGroup>(account, provider, ContactFactory, GroupFactory) {
+
+    object ContactFactory: AndroidContactFactory<AndroidContact> {
+
+        override fun newInstance(addressBook: AndroidAddressBook<AndroidContact, AndroidGroup>, id: Long, fileName: String?, eTag: String?) =
+                AndroidContact(addressBook, id, fileName, eTag)
+
+        override fun newInstance(addressBook: AndroidAddressBook<AndroidContact, AndroidGroup>, contact: Contact, fileName: String?, eTag: String?): AndroidContact =
+                AndroidContact(addressBook, contact, fileName, eTag)
+
+    }
+
+
+    object GroupFactory: AndroidGroupFactory<AndroidGroup> {
+
+        override fun newInstance(addressBook: AndroidAddressBook<AndroidContact, AndroidGroup>, id: Long, fileName: String?, eTag: String?) =
+                AndroidGroup(addressBook, id, fileName, eTag)
+
+        override fun newInstance(addressBook: AndroidAddressBook<AndroidContact, AndroidGroup>, contact: Contact, fileName: String?, eTag: String?) =
+                AndroidGroup(addressBook, contact, fileName, eTag)
+
+    }
+    
+}
\ No newline at end of file

src/main/java/at/bitfire/vcard4android/AndroidAddressBook.java

-/*
- * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the GNU Public License v3.0
- * which accompanies this distribution, and is available at
- * http://www.gnu.org/licenses/gpl.html
- */
-
-package at.bitfire.vcard4android;
-
-import android.accounts.Account;
-import android.content.ContentProviderClient;
-import android.content.ContentValues;
-import android.database.Cursor;
-import android.database.DatabaseUtils;
-import android.net.Uri;
-import android.os.RemoteException;
-import android.provider.ContactsContract;
-import android.provider.ContactsContract.Groups;
-import android.provider.ContactsContract.RawContacts;
-
-import java.io.FileNotFoundException;
-import java.util.LinkedList;
-import java.util.List;
-
-import lombok.Cleanup;
-
-public class AndroidAddressBook {
-	public Account account;
-	final public ContentProviderClient provider;
-	final AndroidGroupFactory groupFactory;
-	final AndroidContactFactory contactFactory;
-
-	public AndroidAddressBook(Account account, ContentProviderClient provider, AndroidGroupFactory groupFactory, AndroidContactFactory contactFactory) {
-		this.account = account;
-		this.provider = provider;
-		this.groupFactory = groupFactory;
-		this.contactFactory = contactFactory;
-	}
-
-
-	// account-specific address book settings
-
-    @SuppressWarnings("Recycle")
-	public ContentValues getSettings() throws ContactsStorageException {
-		try {
-			@Cleanup Cursor cursor = provider.query(syncAdapterURI(ContactsContract.Settings.CONTENT_URI), null, null, null, null);
-			if (cursor != null && cursor.moveToNext()) {
-				ContentValues values = new ContentValues();
-				DatabaseUtils.cursorRowToContentValues(cursor, values);
-				return values;
-			} else
-				throw new FileNotFoundException();
-		} catch(FileNotFoundException|RemoteException e) {
-			throw new ContactsStorageException("Couldn't read contacts settings", e);
-		}
-	}
-
-	public void updateSettings(ContentValues values) throws ContactsStorageException {
-		values.put(ContactsContract.Settings.ACCOUNT_NAME, account.name);
-		values.put(ContactsContract.Settings.ACCOUNT_TYPE, account.type);
-		try {
-			provider.insert(syncAdapterURI(ContactsContract.Settings.CONTENT_URI), values);
-		} catch(RemoteException e) {
-			throw new ContactsStorageException("Couldn't write contacts settings", e);
-		}
-	}
-
-
-	// account-specific address book sync state
-
-	public byte[] getSyncState() throws ContactsStorageException {
-		try {
-			return ContactsContract.SyncState.get(provider, account);
-		} catch (RemoteException e) {
-			throw new ContactsStorageException("Couldn't read contacts sync state", e);
-		}
-	}
-
-	public void setSyncState(byte[] data) throws ContactsStorageException {
-		try {
-			ContactsContract.SyncState.set(provider, account, data);
-		} catch (RemoteException e) {
-			throw new ContactsStorageException("Couldn't write contacts sync state", e);
-		}
-	}
-
-
-	// groups
-
-    @SuppressWarnings("Recycle")
-	protected AndroidGroup[] queryGroups(String where, String[] whereArgs) throws ContactsStorageException {
-		try {
-			@Cleanup Cursor cursor = provider.query(syncAdapterURI(Groups.CONTENT_URI),
-					new String[] { Groups._ID, AndroidGroup.COLUMN_FILENAME, AndroidGroup.COLUMN_ETAG }, where, whereArgs, null);
-
-			List<AndroidGroup> groups = new LinkedList<>();
-			while (cursor != null && cursor.moveToNext())
-				groups.add(groupFactory.newInstance(this, cursor.getLong(0), cursor.getString(1), cursor.getString(2)));
-			return groups.toArray(groupFactory.newArray(groups.size()));
-		} catch (RemoteException e) {
-			throw new ContactsStorageException("Couldn't query contact groups", e);
-		}
-	}
-
-    @SuppressWarnings("Recycle")
-    protected AndroidContact[] queryContacts(String where, String[] whereArgs) throws ContactsStorageException {
-		try {
-			@Cleanup Cursor cursor = provider.query(syncAdapterURI(RawContacts.CONTENT_URI),
-					new String[] { RawContacts._ID, AndroidContact.COLUMN_FILENAME, AndroidContact.COLUMN_ETAG },
-                    where, whereArgs, null);
-
-			List<AndroidContact> contacts = new LinkedList<>();
-			while (cursor != null && cursor.moveToNext())
-				contacts.add(contactFactory.newInstance(this, cursor.getLong(0), cursor.getString(1), cursor.getString(2)));
-			return contacts.toArray(contactFactory.newArray(contacts.size()));
-		} catch (RemoteException e) {
-			throw new ContactsStorageException("Couldn't query contacts", e);
-		}
-	}
-
-
-	// helpers
-
-	public Uri syncAdapterURI(Uri uri) {
-		return uri.buildUpon()
-				.appendQueryParameter(RawContacts.ACCOUNT_NAME, account.name)
-				.appendQueryParameter(RawContacts.ACCOUNT_TYPE, account.type)
-				.appendQueryParameter(ContactsContract.CALLER_IS_SYNCADAPTER, "true")
-				.build();
-	}
-
-}

src/main/java/at/bitfire/vcard4android/AndroidAddressBook.kt

+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.vcard4android
+
+import android.accounts.Account
+import android.annotation.SuppressLint
+import android.content.ContentProviderClient
+import android.content.ContentValues
+import android.database.DatabaseUtils
+import android.net.Uri
+import android.os.RemoteException
+import android.provider.ContactsContract
+import android.provider.ContactsContract.Groups
+import android.provider.ContactsContract.RawContacts
+import java.io.FileNotFoundException
+import java.util.*
+
+open class AndroidAddressBook<out T1: AndroidContact, out T2: AndroidGroup>(
+        var account: Account,
+        val provider: ContentProviderClient,
+        val contactFactory: AndroidContactFactory<T1>,
+        val groupFactory: AndroidGroupFactory<T2>
+) {
+
+	// account-specific address book settings
+
+    @Throws(ContactsStorageException::class)
+	fun getSettings(): ContentValues {
+        val values = ContentValues()
+        try {
+			provider.query(syncAdapterURI(ContactsContract.Settings.CONTENT_URI), null, null, null, null)?.use { cursor ->
+                if (cursor.moveToNext())
+                    DatabaseUtils.cursorRowToContentValues(cursor, values)
+                else
+                    throw FileNotFoundException()
+            }
+		} catch(e: Exception) {
+			throw ContactsStorageException("Couldn't read address book settings", e)
+		}
+        return values
+	}
+
+    @Throws(ContactsStorageException::class)
+	fun updateSettings(values: ContentValues) {
+		values.put(ContactsContract.Settings.ACCOUNT_NAME, account.name)
+		values.put(ContactsContract.Settings.ACCOUNT_TYPE, account.type)
+		try {
+			provider.insert(syncAdapterURI(ContactsContract.Settings.CONTENT_URI), values)
+		} catch(e: RemoteException) {
+			throw ContactsStorageException("Couldn't write address book settings", e)
+		}
+	}
+
+
+	// account-specific address book sync state
+
+    @Throws(ContactsStorageException::class)
+	fun getSyncState(): ByteArray =
+		try {
+			ContactsContract.SyncState.get(provider, account)
+		} catch(e: RemoteException) {
+			throw ContactsStorageException("Couldn't read address book sync state", e)
+		}
+
+    @Throws(ContactsStorageException::class)
+	fun setSyncState(data: ByteArray) {
+		try {
+			ContactsContract.SyncState.set(provider, account, data)
+		} catch(e: RemoteException) {
+			throw ContactsStorageException("Couldn't write contacts sync state", e)
+		}
+	}
+
+
+	// groups
+
+    @SuppressLint("Recycle")
+    @Throws(ContactsStorageException::class)
+    protected fun queryContacts(where: String?, whereArgs: Array<String>?): List<T1> {
+        val contacts = LinkedList<T1>()
+        try {
+            provider.query(syncAdapterURI(RawContacts.CONTENT_URI),
+                    arrayOf(RawContacts._ID, AndroidContact.COLUMN_FILENAME, AndroidContact.COLUMN_ETAG),
+                    where, whereArgs, null)?.let { cursor ->
+                while (cursor.moveToNext())
+                    contacts += contactFactory.newInstance(this, cursor.getLong(0), cursor.getString(1), cursor.getString(2))
+            }
+        } catch(e: RemoteException) {
+            throw ContactsStorageException("Couldn't query contacts", e)
+        }
+        return contacts
+    }
+
+    @SuppressLint("Recycle")
+    @Throws(ContactsStorageException::class)
+	protected fun queryGroups(where: String?, whereArgs: Array<String>?): List<T2> {
+        val groups = LinkedList<T2>()
+		try {
+			provider.query(syncAdapterURI(Groups.CONTENT_URI),
+					arrayOf(Groups._ID, AndroidGroup.COLUMN_FILENAME, AndroidGroup.COLUMN_ETAG),
+                    where, whereArgs, null)?.use { cursor ->
+                while (cursor.moveToNext())
+                    groups += groupFactory.newInstance(this, cursor.getLong(0), cursor.getString(1), cursor.getString(2))
+            }
+		} catch(e: RemoteException) {
+			throw ContactsStorageException("Couldn't query contact groups", e)
+		}
+        return groups
+	}
+
+
+	// helpers
+
+	fun syncAdapterURI(uri: Uri) = uri.buildUpon()
+				.appendQueryParameter(RawContacts.ACCOUNT_NAME, account.name)
+				.appendQueryParameter(RawContacts.ACCOUNT_TYPE, account.type)
+				.appendQueryParameter(ContactsContract.CALLER_IS_SYNCADAPTER, "true")
+				.build()!!
+
+}

src/main/java/at/bitfire/vcard4android/AndroidContactFactory.java

-/*
- * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the GNU Public License v3.0
- * which accompanies this distribution, and is available at
- * http://www.gnu.org/licenses/gpl.html
- */
-
-package at.bitfire.vcard4android;
-
-public class AndroidContactFactory {
-
-	public static final AndroidContactFactory INSTANCE = new AndroidContactFactory();
-
-	public AndroidContact newInstance(AndroidAddressBook addressBook, long id, String fileName, String eTag) {
-		return new AndroidContact(addressBook, id, fileName, eTag);
-	}
-
-    public 	AndroidContact newInstance(AndroidAddressBook addressBook, Contact contact, String fileName, String eTag) {
-		return new AndroidContact(addressBook, contact, fileName, eTag);
-	}
-
-    public AndroidContact[] newArray(int size) {
-		return new AndroidContact[size];
-	}
-
-}

src/main/java/at/bitfire/vcard4android/AndroidContactFactory.kt

+/*
+ * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the GNU Public License v3.0
+ * which accompanies this distribution, and is available at
+ * http://www.gnu.org/licenses/gpl.html
+ */
+
+package at.bitfire.vcard4android
+
+interface AndroidContactFactory<out T: AndroidContact> {
+
+    fun newInstance(addressBook: AndroidAddressBook<AndroidContact, AndroidGroup>, id: Long, fileName: String?, eTag: String?): T
+    fun newInstance(addressBook: AndroidAddressBook<AndroidContact, AndroidGroup>, contact: Contact, fileName: String?, eTag: String?): T
+
+}

src/main/java/at/bitfire/vcard4android/AndroidGroup.java

-/*
- * Copyright © 2013 – 2015 Ricki Hirner (bitfire web engineering).
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the GNU Public License v3.0
- * which accompanies this distribution, and is available at
- * http://www.gnu.org/licenses/gpl.html
- */
-
-package at.bitfire.vcard4android;
-
-import android.annotation.SuppressLint;
-import android.content.ContentUris;
-import android.content.ContentValues;
-import android.database.Cursor;
-import android.net.Uri;
-import android.os.RemoteException;
-import android.provider.ContactsContract;
-import android.provider.ContactsContract.CommonDataKinds.GroupMembership;
-import android.provider.ContactsContract.Groups;
-import android.provider.ContactsContract.RawContacts;
-import android.provider.ContactsContract.RawContacts.Data;
-
-import org.apache.commons.lang3.StringUtils;
-
-import java.io.FileNotFoundException;
-
-import lombok.Cleanup;
-import lombok.Getter;
-import lombok.ToString<