can anyone please explain the following behavior ``` class A kotlinlang #getting-started

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Title

kartikpatodi

11/05/2018, 7:12 PM

can anyone please explain the following behavior

class A1(private val x: Int) {
    private val y: Int = 0
}

generates this code in Java

public final class A1 {
    private final int y;
    private final int x;

    public A1(int x) {
        this.x = x;
    }
}

while

class A2(private val x: Int) {
    private val y: Int
    init {
        y = 0
    }
}

generates

public final class A2 {
    private final int y;
    private final int x;

    public A2(int x) {
        this.x = x;
        this.y = 0;
    }
}

Why if init block

y=0

is in constructor of

A2

and not otherwise in case of

A1

marstran

11/05/2018, 7:15 PM

Use backtics ``` instead of ''' to format the code.

kartikpatodi

11/05/2018, 7:16 PM

edited

Mike

11/05/2018, 7:42 PM

init

in Kotlin is part of the construction process for a class, hence the code being emitted in the constructor. In your simple example, you could obviously just assign

to y when you define it. Help?

kartikpatodi

11/05/2018, 8:01 PM

@Mike ok so does both express same behaviour?

also I experimented a bit and

class A1(private val x: Int) {
    private val y: Int = 2
}

generates

public final class A1 {
   private final int y;
   private final int x;

   public A1(int x) {
      this.x = x;
      this.y = 2;
   }
}

Which means it is omitting the constructor assignment only in the case of default values is supplied like

for

Int

Which seems reasonable but if someone can confirm this.

👍 1

karelpeeters

11/05/2018, 8:44 PM

What's the problem? It doesn't matter whether the

= 0

is generated, right?

Mike

11/05/2018, 8:54 PM

I suspect they want to better understand what gets generated, so they're digging in. As to why, only they can answer that.

kartikpatodi

11/06/2018, 6:46 PM

@Mike Actually was converting some legacy java code and did not understand the reason for the behavior, but now I gotit I think..

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