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Java Reflection - Method.getParameterAnnotations() Examples

Java Reflection Java Java API 

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Class:

java.lang.reflect.Method

java.lang.Objectjava.lang.Objectjava.lang.reflect.AccessibleObjectjava.lang.reflect.AccessibleObjectjava.lang.reflect.AnnotatedElementAnnotatedElementjava.lang.reflect.Executablejava.lang.reflect.Executablejava.lang.reflect.MemberMemberjava.lang.reflect.GenericDeclarationGenericDeclarationjava.lang.reflect.Methodjava.lang.reflect.MethodLogicBig

Method:

public Annotation[][] getParameterAnnotations()

Returns an array of arrays of Annotations that represent the annotations on the formal parameters, in declaration order, of the Method represented by this object.


Examples


package com.logicbig.example.method;

import java.lang.annotation.*;
import java.lang.reflect.Method;
import java.util.Arrays;

public class GetParameterAnnotationsExample {

    public void displayData(@DisplayConfig Object config) {}

    public static void main(String... args) throws NoSuchMethodException {
        Method m = GetParameterAnnotationsExample.class.getDeclaredMethod("displayData", Object.class);
        Annotation[][] pas = m.getParameterAnnotations();
        System.out.println(Arrays.deepToString(pas));
    }

    @Target({ElementType.PARAMETER})
    @Retention(RetentionPolicy.RUNTIME)
    private @interface DisplayConfig {}
}

Output

[[@com.logicbig.example.method.GetParameterAnnotationsExample$DisplayConfig()]]




Using multiple annotations:

package com.logicbig.example.method;

import java.lang.annotation.*;
import java.lang.reflect.Method;
import java.util.Arrays;

public class GetParameterAnnotationsExample2 {
    public void displayData(@DisplayConfig Object config,
                            @Deprecated @INDEX int n) {}

    public static void main(String... args) throws NoSuchMethodException {
        Method m = GetParameterAnnotationsExample2.class.getDeclaredMethod("displayData",
                Object.class, int.class);
        Annotation[][] pas = m.getParameterAnnotations();
        System.out.println("-- all parameter annotations --");
        System.out.println(Arrays.deepToString(pas));
        for (Annotation[] pa : pas) {
            System.out.println("-- parameter annotations --");
            for (Annotation annotation : pa) {
                System.out.println(annotation);
            }
        }
    }

    @Target({ElementType.PARAMETER})
    @Retention(RetentionPolicy.RUNTIME)
    private @interface INDEX {}

    @Target({ElementType.PARAMETER})
    @Retention(RetentionPolicy.RUNTIME)
    private @interface DisplayConfig {}
}

Output

-- all parameter annotations --
[[@com.logicbig.example.method.GetParameterAnnotationsExample2$DisplayConfig()], [@java.lang.Deprecated(forRemoval=false, since=""), @com.logicbig.example.method.GetParameterAnnotationsExample2$INDEX()]]
-- parameter annotations --
@com.logicbig.example.method.GetParameterAnnotationsExample2$DisplayConfig()
-- parameter annotations --
@java.lang.Deprecated(forRemoval=false, since="")
@com.logicbig.example.method.GetParameterAnnotationsExample2$INDEX()

See Also