Java Class isAnnotation()用法及代碼示例

java.lang.Class類的isAnnotation()方法用於檢查此Class是否為Annotation類型。如果此類是Annotation類型，則該方法返回true。否則返回false。

用法:

public boolean isAnnotation()

參數：此方法不接受任何參數。

返回值：如果該類是Annotation類型，則此方法返回true。否則返回false。

下麵的程序演示了isAnnotation()方法。

示例1:

// Java program to demonstrate isAnnotation() method 
  
public class Test { 
    public static void main(String[] args) 
        throws ClassNotFoundException 
    { 
  
        // returns the Class object for this class 
        Class myClass = Class.forName("Test"); 
  
        System.out.println("Class represented by myClass: "
                           + myClass.toString()); 
  
        // Check if this class is an annotation 
        // using isAnnotation() method 
        System.out.println("Is Test an annotation: "
                           + myClass.isAnnotation()); 
    } 
}

輸出：

Class represented by myClass: class Test
Is Test an annotation: false

示例2:

// Java program to demonstrate isAnnotation() method 
  
// declaring an Annotation Type 
@interface A { 
    // Annotation element definitions 
} 
  
public class Test { 
    public static void main(String[] args) 
        throws ClassNotFoundException 
    { 
  
        // returns the Class object for A 
        Class myClass = A.class; 
  
        // Check if myClass is an annotation 
        // using isAnnotation() method 
        System.out.println("Is A an annotation: "
                           + myClass.isAnnotation()); 
    } 
}

輸出：

Is A an annotation: true

參考： https://docs.oracle.com/javase/9/docs/api/java/lang/Class.html#isAnnotation–

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