What are the 4 built in annotations in Java?

What are the 4 built in annotations in Java?

I'm happy to respond in English for once!

In Java, there are four built-in annotations that serve different purposes:

For example:

public class Animal {
public void sound() {
System.out.println("The animal makes a sound.");
}
}
public class Dog extends Animal {
@Override
public void sound() {
System.out.println("The dog barks.");
}
}

For example:

public class Calculator {
public void calculate(int x) {
// This method does nothing
}
@Deprecated
public int multiply(int x, int y) {
return x * y;
}
}

For example:

@SuppressWarnings("unchecked")
public void processList(List<?> list) {
// Code here
}

For example:

@SuppressWarnings("rawtypes")
public void processMap(Map map) {
// Code here
}

These four built-in annotations help developers maintain high-quality code by ensuring correct method overriding, avoiding deprecated methods, suppressing unnecessary compiler warnings, and writing generic code without worrying about unchecked operations.

Java annotation example w3schools

Here's an example of using annotations in Java with W3Schools:

Java is a statically-typed language that uses annotations to provide additional information about the code. Annotations are used to define metadata about the class, method, or field.

In this example, we will use Java annotation @Override to override a method from its superclass.

Example:

// Superclass
public class Animal {
public void sound() {
System.out.println("The animal makes a sound");
}
}
// Subclass
public class Dog extends Animal {
// Overriding the sound() method
@Override
public void sound() {
System.out.println("The dog barks");
}
public static void main(String[] args) {
Dog myDog = new Dog();
myDog.sound(); // Output: The dog barks
}
}

Output:

The dog barks

As you can see, the @Override annotation is used to indicate that the sound() method in the Dog class is overriding a method from its superclass (Animal). This is useful for catching any mistakes if you forget to override a method or if you accidentally create a new method with the same name as one in the superclass.

More Java Annotations:

W3Schools Java Annotation Tutorial:

Here's a tutorial on using annotations in Java provided by W3Schools:

Java Annotations

This tutorial provides more examples and explanations of how to use various Java annotations. It also covers the different types of annotations, including those for classes, methods, fields, and packages.

Conclusion:

Annotations are a powerful tool in Java that allow you to add metadata to your code. By using annotations like @Override, you can make your code more readable and maintainable by explicitly declaring what parts of your code are overriding or implementing certain behaviors. Annotations can also help you catch errors and improve the overall quality of your code.

I hope this helps! Let me know if you have any questions or need further clarification on how to use Java annotations.