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When accessing Kotlin classes from Java, is it possible during runtime to tell if a particular field is nullable or not? Also, is it possible to tell if a class is a data class?
Even a guess would be sufficient for my purposes. Using reflection is also fine.
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Any is only a superclass of non-nullable types. This makes it possible to write code that requires a non-null instance of anything, and still benefit from the safety of the type-checker (unlike when using Java's Object ).
However, we can make a nullable type object, by explicitly informing Kotlin that the object can be null. When using a nullable type, the Secure Access Operation ?. or Not Null Assertion !! operators have to be used to access the nullable variable. The not-null assertion operator ( !! )
You can use the "?. let" operator in Kotlin to check if the value of a variable is NULL. It can only be used when we are sure that we are refereeing to a non-NULL able value.
Android Studio provides full support for Kotlin, enabling you to add Kotlin files to your existing project and convert Java language code to Kotlin. You can then use all of Android Studio's existing tools with your Kotlin code, including autocomplete, lint checking, refactoring, debugging, and more.
If you have a java.lang.reflect.Field instance for a property, you can first obtain the original Kotlin representation of the property by converting it to the kotlin.reflect.KProperty instance with kotlin.reflect.jvm.ReflectJvmMapping, and then get the type and check its nullability or anything else:
public static boolean isNullable(Field field) {
KProperty<?> property = ReflectJvmMapping.getKotlinProperty(field);
return property.getType().isMarkedNullable();
}
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