skydoves

public final class ExtensionFunctionKt {
    public static String addExclamation(String receiver) {
        return receiver + "!";
    }
}

skydoves

fun String.addExclamation(): String {
    return this + "!"
}

fun main() {
    val result = "skydoves".addExclamation()
    println(result) // Output: skydoves!
}

skydoves

int result = 10 * 2;

skydoves

inline fun inlineHigherOrderExample(operation: (Int) -> Int): Int {
    return operation(10)
}

val result = inlineHigherOrderExample { it * 2 }

skydoves

Function1<Integer, Integer> lambda = new Function1<Integer, Integer>() {
    @Override
    public Integer invoke(Integer it) {
        return it * 2;
    }
};
int result = higherOrderExample(lambda);

skydoves

val result = higherOrderExample { it * 2 }

skydoves

int higherOrderExample(Function1<Integer, Integer> operation) {
    return operation.invoke(10);
}

skydoves

fun higherOrderExample(operation: (Int) -> Int): Int {
    return operation(10)
}

skydoves

val id1: Any = UserId("abc")         // Stored as Any, forces boxing
val id2: UserId? = UserId("def")     // Nullable type can force boxing
val listOfIds = listOf(UserId("1"))  // Generic collection, forces boxing

skydoves

public final class IdKt {
    // The function takes the PRIMITIVE type directly
    public static final void processId(String userId) {
        String var1 = "Processing user with ID: " + userId;
        System.out.println(var1);
    }

    public static final void main() {
        // No UserId object allocated
        String myId = UserId.constructor_impl("user-123");