BaseActivity.kt

package tm.alashow.x.ui.base

import android.arch.lifecycle.ViewModel
import android.arch.lifecycle.ViewModelProvider
import android.arch.lifecycle.ViewModelProviders
import android.databinding.DataBindingUtil
import android.databinding.ViewDataBinding
import android.os.Bundle
import android.support.annotation.LayoutRes
import android.support.annotation.StringRes
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.Toolbar
import android.view.MenuItem
import dagger.android.support.DaggerAppCompatActivity
import tm.alashow.x.R
import tm.alashow.x.base.interfaces.OnBackPressedListener
import tm.alashow.x.base.interfaces.OnToolbarClickedListener
import javax.inject.Inject

abstract class BaseActivity<VDB : ViewDataBinding, VM : ViewModel> : DaggerAppCompatActivity() {

    @Inject
    lateinit var viewModelFactory: ViewModelProvider.Factory

    internal lateinit var binding: VDB
    internal lateinit var viewModel: VM

    protected lateinit var toolbarView: Toolbar

    private val onToolbarClickedListeners = HashSet<OnToolbarClickedListener>()
    private val onBackPressedListeners = HashSet<OnBackPressedListener>()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, getLayout())
        viewModel = ViewModelProviders.of(this, viewModelFactory).get(getVmClass())
        binding.setLifecycleOwner(this)

        initViews()
    }

    override fun onBackPressed() {
        for (onBackPressedListener in onBackPressedListeners) {
            if (onBackPressedListener.onBackPressed()) {
                return
            }
        }

        super.onBackPressed()
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        when (item.itemId) {
            android.R.id.home -> {
                onBackPressed()
                return true
            }
        }
        return false
    }

    /**
     * Initializes views
     */
    private fun initViews() {
        setupToolbar(findViewById(R.id.toolbar)!!)
        setTitle(getDefaultTitle())
    }

    /**
     * Setup given toolbar.
     */
    private fun setupToolbar(toolbar: Toolbar) {
        this.toolbarView = toolbar
        setSupportActionBar(this.toolbarView)

        // showing back button on toolbar if child activity
        if (isChildActivity() && supportActionBar != null) {
            supportActionBar!!.setDisplayHomeAsUpEnabled(true)
        }

        toolbar.setOnClickListener({
            for (listener in onToolbarClickedListeners) listener.scrollUp()
        })
    }

    override fun setTitle(@StringRes stringRes: Int) = setTitle(getString(stringRes))

    /**
     * Sets title to actionbar, falling back to toolbarView if getSupportActionBar is null
     *
     * @param title string
     */
    fun setTitle(title: String?) {
        if (supportActionBar != null) {
            supportActionBar!!.title = title
        } else {
            toolbarView.title = title
        }
    }

    /**
     * @return current activity, for god object :)
     */
    protected fun getActivity(): AppCompatActivity {
        return this
    }

    /**
     * @return viewModel class for base to setup.
     */
    protected abstract fun getVmClass(): Class<VM>

    /**
     * @return layout to setup data binding.
     */
    @LayoutRes
    protected abstract fun getLayout(): Int

    /**
     * @return Default actionbar title
     */
    @StringRes
    protected abstract fun getDefaultTitle(): Int

    abstract fun isChildActivity(): Boolean

    // Some listeners

    fun addOnToolbarClickedListener(listener: OnToolbarClickedListener) = onToolbarClickedListeners.add(listener)
    fun removeOnToolbarClickedListener(listener: OnToolbarClickedListener) = onToolbarClickedListeners.remove(listener)
    fun addOnBackPressedListener(listener: OnBackPressedListener) = onBackPressedListeners.add(listener)
    fun removeOnBackPressedListener(listener: OnBackPressedListener) = onBackPressedListeners.remove(listener)
}

BaseFragment.kt

package tm.alashow.x.ui.base

import android.arch.lifecycle.ViewModel
import android.arch.lifecycle.ViewModelProvider
import android.arch.lifecycle.ViewModelProviders
import android.content.Context
import android.databinding.DataBindingUtil
import android.databinding.ViewDataBinding
import android.os.Bundle
import android.support.annotation.LayoutRes
import android.support.annotation.StringRes
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import dagger.android.support.DaggerFragment
import tm.alashow.x.R
import javax.inject.Inject

abstract class BaseFragment<VDB : ViewDataBinding, VM : ViewModel> : DaggerFragment() {

    @Inject
    lateinit var viewModelFactory: ViewModelProvider.Factory

    internal lateinit var binding: VDB
    internal lateinit var viewModel: VM

    protected var fragmentNavigator: FragmentNavigator? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        viewModel = ViewModelProviders.of(this, viewModelFactory).get(getVmClass())
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        binding = DataBindingUtil.inflate(inflater, getLayout(), container, false)
        binding.setLifecycleOwner(this)

        return binding.root
    }

    override fun onAttach(context: Context?) {
        super.onAttach(context)

        if (context is FragmentNavigator) {
            fragmentNavigator = context
        }
    }

    /**
     * Setting title to BaseActivity safer
     */
    fun setTitle(title: String?) {
        try {
            if (activity is BaseActivity<*, *>) {
                (activity as BaseActivity<*, *>).setTitle(title)
            }
        } catch (e: Exception) {
            e.printStackTrace()
        }
    }

    /**
     * @return viewModel class for base to setup.
     */
    protected abstract fun getVmClass(): Class<VM>

    /**
     * @return layout to setup data binding.
     */
    @LayoutRes
    protected abstract fun getLayout(): Int

    /**
     * @return default title for fragment
     */
    @StringRes
    open fun getTitle(): Int {
        return R.string.app_name
    }
}