Fragment Utils by Kotlin

FragmentUtils.kt

/**
 * persistence property that implements Parcelable on Fragment.
 * The set value also write to Fragment.arguments, and always read from Fragment.arguments if need.
 */
class ParcelableProperty<T : Any>(private val defaultValue: T? = null) : kotlin.properties.ReadWriteProperty<Fragment, T> {

    var value: T? = null

    override operator fun getValue(thisRef: android.support.v4.app.Fragment, property: kotlin.reflect.KProperty<*>): T {
        if (value == null) {
            val args = thisRef.arguments ?: throw IllegalStateException("Cannot read property ${property.name} if no arguments have been set")
            @Suppress("UNCHECKED_CAST")
            value = args.get(property.name) as? T
        }
        return (value ?: defaultValue) ?: throw IllegalStateException("Property ${property.name} could not be read")
    }

    override operator fun setValue(thisRef: android.support.v4.app.Fragment, property: kotlin.reflect.KProperty<*>, value: T) {
        val args = thisRef.arguments?.let {
            it
        } ?: run {
            Bundle().also {
                thisRef.arguments = it
            }
        }

        val key = property.name

        this.value = value

        when (value) {
            is String -> args.putString(key, value)
            is Int -> args.putInt(key, value)
            is Short -> args.putShort(key, value)
            is Long -> args.putLong(key, value)
            is Byte -> args.putByte(key, value)
            is Boolean -> args.putBoolean(key, value)
            is ByteArray -> args.putByteArray(key, value)
            is Char -> args.putChar(key, value)
            is CharArray -> args.putCharArray(key, value)
            is CharSequence -> args.putCharSequence(key, value)
            is Float -> args.putFloat(key, value)
            is Bundle -> args.putBundle(key, value)
            is Binder -> BundleCompat.putBinder(args, key, value)
            is android.os.Parcelable -> args.putParcelable(key, value)
            is ArrayList<*> -> args.putParcelableArrayList(key, ArrayList(value.filterIsInstance<Parcelable>()))
            is java.io.Serializable -> args.putSerializable(key, value)
            else -> throw IllegalStateException("Type ${value.javaClass.canonicalName} of property ${property.name} is not supported")
        }
    }
}