如果此Package中存在这样的注释,则使用java.lang.Package类的getAnnotation()方法来获取指定注释类型的注释。该方法以对象的形式返回该Package。
用法:
public T getAnnotation(Class<T> annotationClass)
参数:此方法接受参数注释类,它是要获取的注释的类型。
返回值:此方法返回注释包的指定对象。
异常:该方法抛出:
- NullPointerException :如果给定的注释类为null。
下面的程序演示了getAnnotation()方法。
范例1:
// Java program to demonstrate
// getAnnotation() method
import java.util.*;
import java.lang.annotation.*;
// create a custom Annotation
@Retention(RetentionPolicy.RUNTIME)
@interface Annotation {
// This annotation has two attributes.
public String key();
public String value();
}
// call Annotation for method
// and pass values for annotation
@Annotation(key = "GFG", value = "GeeksForGeeks")
public class Test {
public static void main(String[] args)
throws ClassNotFoundException
{
// returns the Class object for this class
Class myClass = Test.class;
System.out.println("Class represented by myClass:"
+ myClass.toString());
// Get the annotation
// using getAnnotation() method
System.out.println(
"Annotation of myClass:"
+ myClass.getAnnotation(
Annotation.class));
}
}
输出:
Class represented by myClass:class Test
Annotation of myClass:@Annotation(key=GFG, value=GeeksForGeeks)
范例2:
// Java program to demonstrate
// getAnnotation() method
import java.util.*;
import java.lang.annotation.*;
// Class with no annotations
// getAnnotation() will return null
public class Test {
public static void main(String[] args)
throws ClassNotFoundException
{
// returns the Class object for this class
Class myClass = Test.class;
System.out.println("Class represented by myClass:"
+ myClass.toString());
// Get the annotation
// using getAnnotation() method
System.out.println(
"Annotation of myClass:"
+ myClass.getAnnotation(
Annotation.class));
}
}
输出:
Class represented by myClass:class Test
Annotation of myClass:null
参考: https://docs.oracle.com/javase/9/docs/api/java/lang/Package.html#getAnnotation-java.lang.Class-
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注:本文由纯净天空筛选整理自guptayashgupta53大神的英文原创作品 Package getAnnotation() method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。