Create an instance of an abstract class in Kotlin

Question

I'm new to Kotlin and I'm trying to use it in my Android project. I have this code:

public var oneTouchTimer: CountDownTimer = CountDownTimer(500, 100) {
    override fun onTick(l: Long) {

    }

    override fun onFinish() {

    }
}

And it's throwing the error:

Cannot create an instance of an abstract class.

Basically I'm trying to create an instance of CountDownTimer and cannot figure out how to convert it to Kotlin.

Here is the code in Java:

CountDownTimer oneTouchTimer = new CountDownTimer(500, 100) {
    @Override
    public void onTick(long l) {

    }

    @Override
    public void onFinish() {

    }
};

score 236 · Accepted Answer · edited Dec 16 '20 at 08:50

236

You can use this method:

var variableName = object: CountDownTimer(...){
    ...
}

These are called "object expressions" in Kotlin. The docs are available here: Object expressions

edited Dec 16 '20 at 08:50

Ayush Shrestha

194
1
7

answered Dec 07 '15 at 21:33

Kota1921

2,451
1
10
13

47

For those curious, these are called "object expressions" in Kotlin. The docs are available here: https://kotlinlang.org/docs/reference/object-declarations.html – Ronald Martin Jul 09 '16 at 22:21
Is it possible to assign a `simpleName` value to an object expression? – Big Money May 07 '21 at 00:37
How can you assign the object **variableName** to null at some point later in the code? – Muhammad Oct 29 '21 at 08:19
Look like you should use nullable, for example var variableName: CountDownTimer? = object: ... – Kota1921 Nov 09 '21 at 12:33

score -2 · Answer 2 · answered Nov 22 '22 at 07:45

-2

Just makes sure you have compatible data types

answered Nov 22 '22 at 07:45

Mark S. Khalil

113
1
4

This does not answer the question at all. OP asked about syntax to instantiate abstract classes. – Ercksen Nov 26 '22 at 16:02

Create an instance of an abstract class in Kotlin

2 Answers2

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