Important Annotations for Java vs Kotlin vs Dart vs Jetpack Compose

Overview

Annotations provide metadata to compilers and frameworks.

Comparison Table

@Override

override

@override

override

@Nullable

String?

String?

String?

@Composable

@Deprecated

@Deprecated

@Deprecated

data class

@immutable

@Immutable

Java Annotations

javaCopy
@Override
public void onClick(View v) { }

@Nullable
String getName() { return name; }

@NonNull
String getEmail() { return email; }

@UiThread
public void updateUI() { }

@WorkerThread
public void fetchData() { }

Kotlin Annotations

kotlinCopy
override fun onClick(v: View) { }

@Deprecated("Use newMethod()")
fun oldMethod() { }

@JvmStatic
fun staticMethod() { }

Dart Annotations

dartCopy
@override
void initState() {
  super.initState();
}

@immutable
class MyWidget extends StatelessWidget { }

@visibleForTesting
void testHelper() { }

Jetpack Compose Annotations

kotlinCopy
@Composable
fun Greeting(name: String) {
    Text("Hello $name")
}

@Preview
@Composable
fun GreetingPreview() {
    Greeting("Android")
}

@Immutable
data class User(val name: String)

Key Point: Modern languages build features into syntax, reducing annotation needs.