TemplateThree

An Android template project that uses Kotlin MVVM DataBinding OkHttp Room Kodein and BottomNavigationView.

Main Features

• Manage Fragments Easily
• Simple and Rich HTTP Request System
• Change Language in Runtime Easily
• Change and Customize Themes
• Easy Shared Element Transition
• Simple Fragments
• Simple RecyclerView Adapters
• Rich Extentions

ApplicationClass

This is the Application class and provides the following features:

Change Language in Runtime

To change application language, call changeLang and pass the Languages enum value to the function. Changing language in different versions of android is a headache. So I created a new system to change language. Intead of strings.xml file, follow the example and add all strings to ApplicationClass. All classes and also layouts have access to ApplicationClass.

appClass.changeLang(Languages.EN)

//XML
android:text="@{data.myLocalizedString}"

//CLASS
val myString = appClass.myLocalizedString

Change Theme in Runtime

To change applicatio theme, call changeTheme and pass the Themes enum value to the function. Available themes are added in styles.xml and you can set different color for anything you want. Also there is an enum for each theme. Please note that having Dark in theme name changes the application theme to dark mode.

appClass.changeTheme(Themes.DARK_BLUE)

Excrypted Shared Preferences

Call setPref to save a value and call getStringPref, getBooleanPref, getIntPref, getLongPref or getFloatPref to get the saved value. It's best to create the preferences keys in Constants to avoid typo mistakes.

appClass.setPref(PREF_MY_BOOLEAN,true)
appClass.setPref(PREF_MY_INT,26)
appClass.setPref(PREF_MY_LONG,26L)
appClass.setPref(PREF_MY_FLOAT,2.6F)
appClass.setPref(PREF_MY_STRING,"Twenty Six")

val myBoolean = appClass.getBooleanPref(PREF_MY_BOOLEAN)
val mtInt = appClass.getIntPref(PREF_MY_INT)
val myLong = appClass.getLongPref(PREF_MY_LONG)
val myFloat = appClass.getFloatPref(PREF_MY_FLOAT)
val myString = appClass.getStringPref(PREF_MY_STRING)

Fonts

There are some fonts initialized in ApplicationClass and can be accessed anywhere in classes and layouts. However its best to access fonts using @font/... in xmls.

//XML
android:fontFamily="@font/font_medium"
//or
android:fontFamily="@{appClass.fontMedium}"

//CLASS
val myTypeface = appClass.fontMedium

Universal RecyclerView Animation

There is a LayoutAnimationController instance initialized and can be used as row animations.

//XML
android:layoutAnimation="@{appClass.recyclerViewAnimation}"

//CLASS
binding.templateRvTemp.layoutAnimation = appClass.recyclerViewAnimation

BaseActivity

There is only one activity and it is BaseActivity. It controls the fragments and the navigation view.

Options:

StartMode

• SingleInstance: Only one instance of each fragment can be created in each tab.
• MultiInstance: Multiple instances of a fragment can be created.

ExitMode

• Normal: After reaching the base fragment in a tab, pressing back button will exit the application.
• BackToFirstTab: After reaching the base fragment in a tab, if it is not the first tab, it returns to fist tab.

TransitionAnimation The animation of switching between fragments. Possible values are:

• TRANSIT_FRAGMENT_FADE
• TRANSIT_FRAGMENT_OPEN
• TRANSIT_FRAGMENT_CLOSE
• TRANSIT_NONE

Important Functions:

setLoading

Shows a ProgressBar and disables touch. It has an option to disable touch without showing a loading.

//Show loading and disable touch
setLoading(true)

//Disable touch without showing a loading
setLoading(true,true)

start

Starts a new fragment. You can use BaseFragmentFactory to get a fragment instance.

start(BaseFragmentFactory.templateFragment())

selectTab

Navigate between navigation tabs. There is alse an enum that holds the tab indexes in BaseActivity.

selectTab(BaseActivity.TAB_ONE)

initFragmentTable

Call this method and create the initial fragments that will load on each tabs. It's usually called once, in onCreate function of BaseActivity.

initFragmentTable(
    BaseFragmentFactory.templateFragment(),
    BaseFragmentFactory.templateRoomFragment()
)

showHideNavigationBar

Shows/Hides the navigation bar with animation.

//Show (simple example)
baseActivity.showHideNavigationBar(false)

//Hide (complete example)
baseActivity.showHideNavigationBar(true, 500) {
    //do on hide
}

BaseFragment

All fragments inherit this fragment. You must call initialize in onAttach of fragments and pass the layout id and the viewmodel's class. It has the following variables:

• appClass : An instance of ApplicationClass that can be used as Context
• viewModel : An instance of your fragment's ViewModel
• baseActivity : An instance of BaseActivity
• binding : An instance of your ViewDataBinding that can be used to access view

Important Functions:

initialize

initialize(R.layout.fragment_template, TemplateViewModel::class.java)

rebind

Refreshes the view's data

rebind(data)

grantPermission

Grant permissions using this method and result will be posted by OnRequestPermissionResultEvent event.

//Request permissions
grantPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.CAMERA)

//Get results
@Subscribe
fun OnRequestPermissionResultEvent(event: OnRequestPermissionResultEvent) {
  //code here
}

addSharedElement

Call a event to your fragment and add shared element views right before starting a new fragment. Views don't need to have transitionName. You only need to add the view you want to animate and the id of the target view.

addSharedElement(binding.templateIvIconSmall, R.id.template_ivIconLarge)

BaseAdapter:

All adapters inherit this adapter. This is a generic adapter that holds a list of objects and has the option of showing a loading and an add button. Unless the BaseActivity and BaseFragment, this class should be modified based on your project needs. It has the following variables:

• showAdd : Shows an Add button at the beginning
• showLoading : Shows a ProgressBar as loading at the end
• sectionIndex : It is used to differenciate adapters in a nested list
• addIsLeft : Whether you want to show the add button on the left or not
• isHorizontal : Whether your list is horizontal or not
• list : A list of generic objects that bind into rows
• bindList : A list of pairs that contain the position and the ViewDataBinding of rows

In onCreateViewHolder the viewType variable is the position of the item in list. super must be called for positions below zero, to handle loading and add button. For the positions of zero and above, ViewDataBinding of the row must be created and also bindList should be modified just like the example. Create a static view holder class and inherit the BaseViewHolder and pass variables of your needs.

MVVM Workflow

All models extend the BaseObservable to notify changes to view as they change.

There are three kinds of data in a viewmodel.

• Local Variables:

Local variables are simple variables that we always use anywhere.

• SingleLiveEvent variables:

These are outgoing variables that will be observed in fragments. This is a one way flow that goes from viewmodel to fragment.

//VIEWMODEL
//define
val showMyButton: SingleLiveEvent<Boolean> = SingleLiveEvent()

//use
showMyButton.value = true

//FRAGMENT
//observe
showMyButton.observe(viewLifecycleOwner,{
    it?.let {
        myButton.show()
    }
})

• ObservableField variables:

These are variables that bind the view and the layouts will notify when the data changes. It can be also used as two-way binding to get data from user.

//VIEWMODEL
//define
val tvTitleText: ObservableField<String> = ObservableField()

//use
tvTitleText.set("My String")


//XML
//one way
android:text="@{viewModel.tvTitleText}"

//two way
android:text="@={viewModel.tvTitleText}"

Apart from the three variables above, you can call public functions from fragments or layouts.

//VIEWMODEL
//define
fun myFunction() {

}

//FRAGMENT
viewModel.myFunction()

//XML
android:onClick="@{() -> viewModel.myFunction()}"

HTTP Requests

Lets write down the rest later :D