Java annotation: Difference between revisions

Revision as of 16:05, 6 August 2025

Revision as of 22:08, 12 August 2025

Line 60:

<syntaxhighlight lang="java">

public class Animal {

public void speak() {}

}

public String getType() {

Line 86 ⟶ 85:

<syntaxhighlight lang=Java>

// @Twizzle is an annotation to method toggle().

@Twizzle

public void toggle() {

}

}

// Declares the annotation Twizzle.

public @interface Twizzle {

// Declares the annotation Twizzle.

}

public @interface Twizzle {

}

</syntaxhighlight>

Line 99 ⟶ 100:

<syntaxhighlight lang=Java>

// Same as: @Edible(value = true)

@Edible(true)

Item item = new Carrot();

public @interface Edible {

boolean value() default false;

}

@Author(first = "Oompah", last = "Loompah")

Book book = new Book();

public @interface Author {

String first();

String last();

}

</syntaxhighlight>

Line 119 ⟶ 120:

<syntaxhighlight lang=Java>

@Retention(RetentionPolicy.RUNTIME) // Make this annotation accessible at runtime via reflection.

@Target({ElementType.METHOD}) // This annotation can only be applied to class methods.

public @interface Tweezable {}

}

</syntaxhighlight>

Line 261:

String developer() default "Unknown";

String lastModified();

String [] teamMembers();

int meaningOfLife();

}

Line 284:

public class UseCustomAnnotation {

public static void main(String [] args) {

Class<SetCustomAnnotation> classObject = SetCustomAnnotation.class;

readAnnotation(classObject);

Line 291:

static void readAnnotation(AnnotatedElement element) {

try {

System.out.println("Annotation element values: \%n");

if (element.isAnnotationPresent(TypeHeader.class)) {

// getAnnotation returns Annotation type

Annotation singleAnnotation = element.getAnnotation(TypeHeader.class);

element.getAnnotation(TypeHeader.class);

TypeHeader header = (TypeHeader) singleAnnotation;

System.out.printlnprintf("Developer: %s%n" +, header.developer());

System.out.printlnprintf("Last Modified: %s%n" +, header.lastModified());

// teamMembers returned as String []

System.out.print("Team members: ");

for (String member : header.teamMembers()) {

System.out.printprintf(member + "%s, ", member);

System.out.print("\n");}

System.out.println();

System.out.println("Meaning of Life: %s%n"+, header.meaningOfLife());

}

} catch (Exception exception) {