Android Studio Convert Java To Kotlin 2 errors

Question

After Convert Java File to Kotlin File, gives me two errors in same line: In code below show variables and function with error

     lateinit var ncArr: Array<ImageButton>
     lateinit var xBitmap: Bitmap
     lateinit var oBitmap: Bitmap
     lateinit var intArr: IntArray
     lateinit var btnStartGame: Button
     lateinit var btnMenu: Button
     var stop: Boolean = false
     var gameMode: Int = 0
     var umove: Int = 0

    override fun onCreate(savedInstanceState: Bundle?) {
    super.onStart()
    setContentView(R.layout.activity_game)

    ncArr = arrayOfNulls(9)

    ncArr[0] = findViewById(R.id.nc0) as ImageButton
    ncArr[1] = findViewById(R.id.nc1) as ImageButton
    ncArr[2] = findViewById(R.id.nc2) as ImageButton
    ncArr[3] = findViewById(R.id.nc3) as ImageButton
    ncArr[4] = findViewById(R.id.nc4) as ImageButton
    ncArr[5] = findViewById(R.id.nc5) as ImageButton
    ncArr[6] = findViewById(R.id.nc6) as ImageButton
    ncArr[7] = findViewById(R.id.nc7) as ImageButton
    ncArr[8] = findViewById(R.id.nc8) as ImageButton

    ncArr[0].setOnClickListener(this)
    ncArr[1].setOnClickListener(this)
    ncArr[2].setOnClickListener(this)
    ncArr[3].setOnClickListener(this)
    ncArr[4].setOnClickListener(this)
    ncArr[5].setOnClickListener(this)
    ncArr[6].setOnClickListener(this)
    ncArr[7].setOnClickListener(this)
    ncArr[8].setOnClickListener(this)

    xBitmap = BitmapFactory.decodeResource(resources, R.drawable.x)
    oBitmap = BitmapFactory.decodeResource(resources, R.drawable.o)

    intArr = IntArray(9)

    for (i in 0..8) {
        intArr[i] = 0
    }

    btnMenu = findViewById(R.id.btnMenu) as Button
    btnStartGame = findViewById(R.id.btnStartGame) as Button
    btnMenu.setOnClickListener(this)
    btnStartGame.setOnClickListener(this)

    stop = false

    gameMode = intent.getIntExtra("game_mode", 1)
    umove = 1
}

in line ncArr = arrayOfNulls(9) There are errors:

I trying to fix this problem but i don't have more ideas...

Any sollution?

thanks in advance

Son Truong · Accepted Answer · 2018-09-08 10:57:12Z

2

ncArr = arrayOfNulls(9)

The type of ncArr will be Array<ImageButton?>

ncArr[0] = findViewById(R.id.nc0) as ImageButton

You are using unsafe cast operator as, because the cast operator throws an exception if the cast is not possible. Thus, we call it unsafe. What happens if

findViewById(R.id.nc0) as ImageButton

return null, then null cannot assign to ImageButton, it will throw an exception and make your app crash.

To avoid the above error you can use

ncArr[0] = findViewById(R.id.nc0) as ImageButton?

or using safe cast operator as?

ncArr[0] = findViewById(R.id.nc0) as? ImageButton

Remember apply for ncArr[0] to ncArr[8].

Update: Based on your request, you can use this solution:

lateinit var ncArr: Array<ImageButton>
    lateinit var xBitmap: Bitmap
    lateinit var oBitmap: Bitmap
    lateinit var intArr: IntArray
    lateinit var btnStartGame: Button
    lateinit var btnMenu: Button
    var stop: Boolean = false
    var gameMode: Int = 0
    var umove: Int = 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onStart()
        setContentView(R.layout.activity_game)

        ncArr = arrayOf(
                findViewById<ImageButton>(R.id.nc0).apply{setOnClickListener(this@GameActivity)},
                findViewById<ImageButton>(R.id.nc1).apply{setOnClickListener(this@GameActivity)},
                findViewById<ImageButton>(R.id.nc2).apply{setOnClickListener(this@GameActivity)},
                findViewById<ImageButton>(R.id.nc3).apply{setOnClickListener(this@GameActivity)},
                findViewById<ImageButton>(R.id.nc4).apply{setOnClickListener(this@GameActivity)},
                findViewById<ImageButton>(R.id.nc5).apply{setOnClickListener(this@GameActivity)},
                findViewById<ImageButton>(R.id.nc6).apply{setOnClickListener(this@GameActivity)},
                findViewById<ImageButton>(R.id.nc7).apply{setOnClickListener(this@GameActivity)},
                findViewById<ImageButton>(R.id.nc8).apply{setOnClickListener(this@GameActivity)}

        )

        xBitmap = BitmapFactory.decodeResource(resources, R.drawable.x)
        oBitmap = BitmapFactory.decodeResource(resources, R.drawable.o)

        // Your code here
        ...
}

edited Sep 8, 2018 at 10:57

answered Sep 8, 2018 at 10:13

Son Truong

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3 Comments

Kalco Frkata Over a year ago

is correct this way: ncArr[0] = findViewById<ImageButton?>(R.id.nc0)

Son Truong Over a year ago

I see your problem, change lateinit var ncArr: Array<ImageButton> to lateinit var ncArr: Array<ImageButton?>

Son Truong Over a year ago

Let us continue this discussion in chat.

samaromku · Accepted Answer · 2018-09-08 10:01:17Z

0

You trying to put Nullable array into NonNull. You may declare intArr as Array<ImageButton?> and everything will work.

answered Sep 8, 2018 at 10:01

samaromku

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