Java variable in interface in Kotlin way

Question

I am interesting are there any way to replace kotlin interface variable in Java.

E.g. what should i write in java to have same logic

interface ObjectWithId
{
    var id : Long
}

Before facing this problem all my code could be easily converted back to java, but using interface variables breaks 'backward compatibility'. Isn't it?

I'm not clear if you're asking how to create an implementation of this specific interface in your Java code, or how to define an interface in Java with the same functionality as this one. — Tenfour04
– Tenfour04, Commented Mar 29, 2020 at 0:50
One helpful site for these question. It provides a kotlin compiler + java disassembler javap.yawk.at/#O0tyIG/procyon — k5_
– k5_, Commented Mar 29, 2020 at 1:13

Naman · Accepted Answer · 2020-03-29 01:09:03Z

4

In java this interface would be:

public interface ObjectWithId {
    long getId();        
    void setId(long p0);
}

edited Mar 29, 2020 at 1:09

Naman

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answered Mar 29, 2020 at 1:01

k5_

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3 Comments

Bios90 Over a year ago

Thanks for answer, and also i should have some variable in 'implementer' to store id?

Eduardo macedo Over a year ago

This is the correct answer, the var or val in Kotlin are not actually variables, but properties (a setter, getter and backing field joined together). Interfaces are not supposed to hold state, see this.

k5_ Over a year ago

@Bios90 thats open for the implementor, how this property is implemented. Most common would be a private field.

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