In this example we will show how to assign default values to custom annotations. We need first customize an annotation class and add default values for each entry, just as shown below.
Source Code
– MyAnn
package com.beginner.examples;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
@Retention(RetentionPolicy.RUNTIME) //Add this annotation in order to also exist at runtime
public @interface MyAnn {
String key() default "Default value for key";
String value() default "Default value";
}
– UseMyAnn
package com.beginner.examples;
@MyAnn()
public class UseMyAnn {
}
– Test
package com.beginner.examples;
public class Test {
public static void main(String[] args) {
try {
Class class1 = Class.forName("com.beginner.examples.UseMyAnn");
MyAnn ann = class1.getAnnotation(MyAnn.class);
System.out.println("key : " + ann.key());
System.out.println("value : " + ann.value());
} catch (Exception e) {
e.printStackTrace();
}
}
}
Output:
key : Default value for key
value : Default value
References
Imported packages in Java documentation: