Java Annotations Explained

Java annotations provide metadata about your code without affecting its execution. Here’s a basic example:

@Override
public String toString() {
    return "Custom toString implementation";
}

@Deprecated
public void oldMethod() {
    System.out.println("This method is deprecated");
}

You can create custom annotations for various purposes:

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface LogExecutionTime {
    String value() default "";
}

public class Example {
    @LogExecutionTime("Processing data")
    public void processData() {
        // Method implementation
        System.out.println("Processing...");
    }
}

Annotations are widely used in frameworks like Spring and Hibernate for configuration and behavior modification:

@RestController
@RequestMapping("/api")
public class UserController {

    @GetMapping("/users/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.findById(id);
    }
}

javac -cp ".:lib/*" *.java && java -cp ".:lib/*" MainClass

# Java Annotations Explained

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