Accessing constants defined in Kotlin in java class

Question

I have defined some constants in kotlin

object Keys {
    const val SPLASH_DURATION : Long = 5000

    const val READ_TIMEOUT : Int = 200
    const val CONNECTION_TIMEOUT : Int = 200
    const val WRITE_TIMEOUT : Int = 200

    var BASE_URL = BuildConfig.SERVER_KEY
}

If I try to access BASE_URL in a Java class as Keys.BASE_URL. I get the error, It has private access.
How to resolve this. Should I need to declare constants differently in kotlin.

Goku · Accepted Answer · 2019-11-13 07:05:27Z

13

You can use Companion Objects

An object declaration inside a class can be marked with the companion keyword:

Try this way

class Keys {

    companion object {
        const val SPLASH_DURATION : Long = 5000
        const val READ_TIMEOUT : Int = 200
        const val CONNECTION_TIMEOUT : Int = 200
        const val WRITE_TIMEOUT : Int = 200

    }
}

Now you can access your const variable like this

Keys.CONNECTION_TIMEOUT;

Second Way

object Keys {
    const val SPLASH_DURATION: Long = 5000
    const val READ_TIMEOUT: Int = 200
    const val CONNECTION_TIMEOUT: Int = 200
    const val WRITE_TIMEOUT: Int = 200
}

Now you can access your const variable like this

Keys.SPLASH_DURATION;

edited Nov 13, 2019 at 7:05

answered Dec 18, 2018 at 7:52

Goku

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Comments

TheOska · Accepted Answer · 2018-12-18 10:55:55Z

4

How to solve:

Add the @JvmField

Example:

object Keys {
    const val SPLASH_DURATION : Long = 5000

    const val READ_TIMEOUT : Int = 200
    const val CONNECTION_TIMEOUT : Int = 200
    const val WRITE_TIMEOUT : Int = 200

    @JvmField
    var BASE_URL = BuildConfig.SERVER_KEY
}

Why

Use @JvmField annotation on a public field in the object to tell the compiler to not generate any getter or setter
Expose it as a static field in the class

See the kotlin documentation

answered Dec 18, 2018 at 10:55

TheOska

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Comments

Shivesh Karan Mehta · Accepted Answer · 2019-04-15 09:32:33Z

1

You can just create one constants file like above screenshot.

And define your constant value like this without making any companion Objects and access it through out your projects.

your constant values:-

const val SPLASH_DURATION : Long = 5000
const val READ_TIMEOUT : Int = 200
const val CONNECTION_TIMEOUT : Int = 200
const val WRITE_TIMEOUT : Int = 200

And if you want to make companion Object than you can also do it in KOTLIN

for eg--

 class Keys {

   companion object {

       const val SPLASH_DURATION : Long = 5000
        const val READ_TIMEOUT : Int = 200
        const val CONNECTION_TIMEOUT : Int = 200
        const val WRITE_TIMEOUT : Int = 200

    }
}

and fetch it like this--

Keys.READ_TIMEOUT

edited Apr 15, 2019 at 9:32

answered Dec 18, 2018 at 12:54

Shivesh Karan Mehta

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