Get annotated fields from specific class. - Java java.lang.annotation

Java examples for java.lang.annotation:Field Annotation

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Description

Get annotated fields from specific class.

Demo Code


//package com.java2s;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;

public class Main {


    /**/*  w  w  w  .ja v  a  2  s.co  m*/
     * Get annotated fields from specific class. The field should not static
     * 
     * @param clazz
     *            - The class that need to check
     * @param annotationClass
     *            - expecting annotation class that present on the fields
     * @param fieldType
     *            - expecting field type
     * @return Array of fields. Return empty array if now field been find.
     */
    public static Field[] getAnnotatedFields(Class<?> clazz,
            Class<? extends Annotation> annotationClass, Class<?> fieldType) {
        Class<?> cl = clazz;
        // Get all fields of class. We use getDeclaredFields to get
        // private/default/protected/public fields of class
        // As well as fields from super class.
        Collection<Field> fields = new ArrayList<Field>();
        while (cl != null) {
            for (Field f : cl.getDeclaredFields()) {
                fields.add(f);
            }
            cl = cl.getSuperclass();
        }
        Collection<Field> fs = new ArrayList<Field>(1);
        for (Field f : fields) {
            // If this field is not static
            // Has annotation present
            // And type is expecting fieldType
            if (f.isAnnotationPresent(annotationClass)
                    && !Modifier.isStatic(f.getModifiers())
                    && fieldType.isAssignableFrom(f.getType())) {
                fs.add(f);
            }
        }
        return fs.toArray(new Field[fs.size()]);
    }
}

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