How to change Fragment Kotlin

Question

I'm starting in Kotling and I don't know how to change between fragments, I have tried this code:

val manager = supportFragmentManager
    val transaction = manager.beginTransaction()
    transaction.add(R.layout.fragment_information.toInt(), ComplainFragment())
    transaction.commit()

R.layout.fragment_information.toInt()

But i have an error with this parameter because it doesn't find the fragment Id.

Answer 1

I usually use replace to change between fragments. Also change R.layout.fragment_information to R.id.fragment_layout_id only, so no need toInt()

transaction.replace(R.id.fragment_layout_id, fragment)

Here is my suggestion.

    var fragment: Fragment? = null

            when (itemId) {
                        R.id.fragment_information -> {
                            fragment = ComplainFragment()
                        }
            }

            if (fragment != null) {
                    val transaction = supportFragmentManager.beginTransaction()
                    transaction.replace(R.id.fragment_layout_id, fragment)
                    transaction.commit()
            }

Answer 2

The other answers will work but still we can improve a lot by using extension functions in Kotlin.

Add an extension function to the FragmentManager class like below,

inline fun FragmentManager.doTransaction(func: FragmentTransaction.() -> 
FragmentTransaction) {
    beginTransaction().func().commit()
}

then create an extension function to the AppCompatActivity class,

fun AppCompatActivity.addFragment(frameId: Int, fragment: Fragment){
    supportFragmentManager.doTransaction { add(frameId, fragment) }
}


fun AppCompatActivity.replaceFragment(frameId: Int, fragment: Fragment) {
    supportFragmentManager.doTransaction{replace(frameId, fragment)}
}

fun AppCompatActivity.removeFragment(fragment: Fragment) {
    supportFragmentManager.doTransaction{remove(fragment)}
}

Now, to add and remove fragments from any activity, you just need to call like this,

addFragment(R.id.fragment_container, fragment)

replaceFragment(R.id.fragment_container, fragment)

please refer the below link for more info,

https://medium.com/thoughts-overflow/how-to-add-a-fragment-in-kotlin-way-73203c5a450b