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Android Android Activity Lifecycle The Project Adding the Menu

Raveesh Agarwal
Raveesh Agarwal
2,994 Points

The Beauty Of Kotlin!!

Hi! Just wanted to share this over here. I followed the course in Kotlin and translated the whole app. By inherent simplicity, I can't help but admire how expressive my code is, and also, how less the number of lines in the code it already is. I will post my app here, I have used a recyclerVIew for this project! Please let me know if posts that are not questions should go somewhere else.


package `in`.cookytech.golfy

val mHoles = Array<Hole>(18,{ Hole("Hole ${it+1} :", 0) })

data class Hole(
        val mHoleLabel:String,
        var mHoleStrokeCount: Int)


package `in`.cookytech.golfy

import android.support.v7.widget.RecyclerView
import android.view.View
import android.view.ViewGroup
import kotlinx.android.synthetic.main.item.view.*
import org.jetbrains.anko.layoutInflater
import org.jetbrains.anko.sdk25.coroutines.onClick
import org.jetbrains.anko.toast

class HolesAdapter : RecyclerView.Adapter<HolesAdapter.HolesViewHolder>() {
    override fun onBindViewHolder(holder: HolesViewHolder, position: Int) {
        holder.mPlusButton.onClick {
        holder.mMinusButton.onClick {
            if (mHoles[position].mHoleStrokeCount > 0) {
                holder.mCtx.toast("Can't put negative holes!!")
        holder.mHoleLabel.text = mHoles[position].mHoleLabel
        holder.mHoleCount.text = mHoles[position].mHoleStrokeCount.toString()

    override fun getItemCount(): Int = mHoles.size

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): HolesViewHolder {
        val v = parent
                .inflate(R.layout.item, parent, false )
        return HolesViewHolder(v)

    class HolesViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView){
        val mHoleLabel  = itemView.itemHoleNumber!!
        val mHoleCount = itemView.itemHoleCount!!
        val mPlusButton = itemView.itemPlusButton!!
        val mMinusButton = itemView.itemMinusButton!!
        val mCtx = itemView.context!!

I have included the context in the ViewHolder so that I can toast in the onClick subroutiene.


package `in`.cookytech.golfy

import android.annotation.SuppressLint
import android.content.Context
import android.content.SharedPreferences
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.LinearLayoutManager
import android.view.Menu
import android.view.MenuItem
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
    companion object {
        val PREFS_FILE = "in.cookytech.golfy.preferences"
        val KEY_STROKECOUNT = "key_strokecount"
    private lateinit var mSharedPreferences : SharedPreferences
    private lateinit var mEditor: SharedPreferences.Editor

    override fun onCreate(savedInstanceState: Bundle?) {

        mSharedPreferences = getSharedPreferences(PREFS_FILE, Context.MODE_PRIVATE)
        mEditor = mSharedPreferences.edit()

        for (i in 0 until mHoles.size){
            mHoles[i].mHoleStrokeCount = mSharedPreferences.getInt(KEY_STROKECOUNT + i, 0)

        holesRecyclerView.adapter = HolesAdapter()
        holesRecyclerView.layoutManager = LinearLayoutManager(this)

    override fun onPause() {
        for (i in 0 until mHoles.size){
            mEditor.putInt(KEY_STROKECOUNT + i, mHoles[i].mHoleStrokeCount)

    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        return true

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        val id = item.itemId
        if (id == R.id.clearAllPreferences){

            for (hole in mHoles){
                hole.mHoleStrokeCount = 0
        return true

And surprisingly, that was all it took to get the job done!

Ralph Emerson Manzano
Ralph Emerson Manzano
1,370 Points

this would even be more simplified if you used android's data binding library, great work though, will be exploring Kotlin more very soon!