Annotation Types in Java

In Java, there are several built-in annotation types that provide additional information about the code elements they are applied to. Here are some examples of commonly used built-in annotation types:

@Override

The @Override annotation is used to indicate that a method is intended to override a method with the same name and signature in its superclass. This helps the compiler catch errors where a method is intended to override a superclass method but has a different signature.

Example:

class Animal {
   public void makeSound() {
      System.out.println("Animal is making a sound");
   }
}

class Cat extends Animal {
   @Override
   public void makeSound() {
      System.out.println("Meow");
   }
}

@Deprecated

The @Deprecated annotation is used to indicate that a code element (such as a class, method, or field) should no longer be used. This helps developers identify code that may be obsolete or have been replaced by newer APIs.

Example:

@Deprecated
public class OldClass {
   // ...
}

public class NewClass {
   // ...
}

@SuppressWarnings

The @SuppressWarnings annotation is used to suppress compiler warnings for a specific code element. This can be useful in cases where the developer knows that a particular warning can be safely ignored.

Example:

@SuppressWarnings("unchecked")
public List<String> getList() {
   return (List<String>) Collections.EMPTY_LIST;
}

@FunctionalInterface

The @FunctionalInterface annotation is used to indicate that an interface is intended to be a functional interface, i.e., an interface that has only one abstract method. This can be useful in cases where the developer wants to create lambda expressions or method references using the interface.

Example:

@FunctionalInterface
public interface MyInterface {
   void doSomething();
}

@SafeVarargs

The @SafeVarargs annotation is used to indicate that a method is safe to call with a variable number of arguments of a specific type. This can be useful in cases where the developer wants to avoid warnings or errors related to unsafe use of varargs.

Example:

@SafeVarargs
public final <T> void myMethod(T... args) {
   // ...
}