Declare ImageView in kotlin Android Studio

Question

What I want is to do this (which is in Java):

public class MainActivity exteds AppCompatActivity{
    ImageView logo;

    @override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        logo = findViewById(R.id.logo);
    }

when taking it to Kotlin I get an error:

enter image description here

Please could you tell me which of the options to keep so that the error does not appear?

enter image description here

and what class is TODO()?

People here will like it more, of you add the error message and code, rather than links to images. — Curiosa Globunznik, Nov 01 '20 at 15:05

Ali Ahsan · Accepted Answer · 2020-11-05T06:54:01.917

3

Use lateinit which will allow you to initialize the property later on.

lateinit var logo: ImageView

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    logo = findViewById(R.id.logo)
}

edited Nov 05 '20 at 06:54

answered Nov 01 '20 at 15:12

Ali Ahsan

985
11
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What language is this? It's not Java or Kotlin – Ryan M Nov 05 '20 at 02:43
updated the answer. – Ali Ahsan Nov 05 '20 at 06:54

score 1 · Answer 2 · answered Nov 01 '20 at 15:20

1

You can initialize as null and later use it

var logo: ImageView? = null
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.simple_layout)
        logo = findViewById(R.id.imageView)
    }

answered Nov 01 '20 at 15:20

ruben

1,745
5
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this should be the accepted answer, short and simple – Raj Bedi Dec 16 '22 at 07:37

score 1 · Answer 3 · answered Nov 02 '20 at 07:24

You can't reassign a val, so I would suggest you make it a var. Since you also want to initialize it later, you will need to declare a lateinit var, i.e lateinit var logo: ImageView or you can initialize it as null i.e var logo: ImageView? = null and then later you can reassign as initented logo = findViewById(R.id.logo)

score 0 · Answer 4 · answered Nov 01 '20 at 15:17

If you want to use this logo = findViewById(R.id.logo); in kotlin then you don't need to declare any extra variable you can simply use logo.setOnClickListener { } or anything similar kotlin will directly import it from your xml.(Note :- here logo is your imageView id).

All though if you want to declare any variable and initialize it later on then you can use lateinit var logo: ImageView or simply and nullable variable like var logo: ImageView? = null and initialize it later on. There are a lot of blogs and S.O Questions on google where you can find more about lateinit and nullable variables. Here is one of the S.O question you can refer.

Declare ImageView in kotlin Android Studio

4 Answers4