Kotlin common classes for android

activitity_fragment_container.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/fragment_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <include
        layout="@layout/toolbar"/>

</LinearLayout>

BaseActivity.kt

import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.Toolbar

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 * Created by Silmood on 04/2016
 */
abstract class BaseActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(getLayout())
        setupToolbar()
    }

    fun setupToolbar() {
        val toolbar : Toolbar? = findViewById(R.id.toolbar) as Toolbar

        if(toolbar != null) {
            setSupportActionBar(toolbar)
        }
    }

    abstract fun getLayout() : Int
}

FragmentContainerActivity.kt

import android.os.Bundle
import android.support.v4.app.Fragment

/**
 *  Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 * Created by Silmood on 02/2016.
 */
abstract class FragmentContainerActivity : BaseActivity() {

    override fun onCreate(savedInstanceState: Bundle?){
        super.onCreate(savedInstanceState)

        val fragment : Fragment? = supportFragmentManager.findFragmentById(R.id.fragment_container)

        if(fragment == null){
            supportFragmentManager.beginTransaction()
            .add(R.id.fragment_container, createFragment())
            .commit()
        }
    }

    abstract fun createFragment() : Fragment
}

toolbar.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?attr/colorPrimary"
    android:minHeight="?attr/actionBarSize"
    app:titleTextColor="@android:color/white"
    app:popupTheme="@style/ThemeOverlay.AppCompat.Dark"/>