How to convert the given code to kotlin?

Question

Java

Good afternoon, I am rewriting my packages for Kotlin and ran into a problem, namely that it is impossible to assign and return to Kotlin. The code that was:

public class Packet
{
    private ByteBuf buf;

    protected ByteBuf buf()
    {
        return buf != null ? buf : (buf = Unpooled.buffer());
    }

    @Override
    public final void fromBytes(ByteBuf buf)
    {
        this.buf = buf;
    }

    @Override
    public final void toBytes(ByteBuf buf)
    {
        if (buf != null)
            buf.writeBytes(this.buf);
    }
}

Same code but in kotlin.

class Packet
{
    private var buf: ByteBuf? = null

    protected fun buf(): ByteBuf
    {
        return buf ?: ({buf = Unpooled.buffer(); buf}()!!)
    }

    override fun fromBytes(buf: ByteBuf)
    {
        this.buf = buf
    }

    override fun toBytes(buf: ByteBuf?)
    {
        buf?.writeBytes(this.buf)
    }
}

The point is that buf() should not return null, but it turns out that null is returned. What went wrong? How to do?

Answer 1

Hello.
Not entirely sure, but if you try this:
return buf ?: Unpooled.buffer()