Field.java

/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.utils.reflect;

import java.lang.reflect.GenericArrayType;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

/**
 * Provides information about, and access to, a single field of a class or
 * interface.
 * 
 * @author nexsoftware
 */
public final class Field {

    private final java.lang.reflect.Field field;

    Field(java.lang.reflect.Field field) {
        this.field = field;
    }

    /** Returns the name of the field. */
    public String getName() {
        return field.getName();
    }

    /**
     * Returns a Class object that identifies the declared type for the field.
     */
    public Class getType() {
        return field.getType();
    }

    /**
     * Returns the Class object representing the class or interface that
     * declares the field.
     */
    public Class getDeclaringClass() {
        return field.getDeclaringClass();
    }

    public boolean isAccessible() {
        return field.isAccessible();
    }

    public void setAccessible(boolean accessible) {
        field.setAccessible(accessible);
    }

    /**
     * Return true if the field does not include any of the {@code private},
     * {@code protected}, or {@code public} modifiers.
     */
    public boolean isDefaultAccess() {
        return !isPrivate() && !isProtected() && !isPublic();
    }

    /** Return true if the field includes the {@code final} modifier. */
    public boolean isFinal() {
        return Modifier.isFinal(field.getModifiers());
    }

    /** Return true if the field includes the {@code private} modifier. */
    public boolean isPrivate() {
        return Modifier.isPrivate(field.getModifiers());
    }

    /** Return true if the field includes the {@code protected} modifier. */
    public boolean isProtected() {
        return Modifier.isProtected(field.getModifiers());
    }

    /** Return true if the field includes the {@code public} modifier. */
    public boolean isPublic() {
        return Modifier.isPublic(field.getModifiers());
    }

    /** Return true if the field includes the {@code static} modifier. */
    public boolean isStatic() {
        return Modifier.isStatic(field.getModifiers());
    }

    /** Return true if the field includes the {@code transient} modifier. */
    public boolean isTransient() {
        return Modifier.isTransient(field.getModifiers());
    }

    /** Return true if the field includes the {@code volatile} modifier. */
    public boolean isVolatile() {
        return Modifier.isVolatile(field.getModifiers());
    }

    /** Return true if the field is a synthetic field. */
    public boolean isSynthetic() {
        return field.isSynthetic();
    }

    /**
     * If the type of the field is parameterized, returns the Class object
     * representing the parameter type at the specified index, null otherwise.
     */
    public Class getElementType(int index) {
        Type genericType = field.getGenericType();
        if (genericType instanceof ParameterizedType) {
            Type[] actualTypes = ((ParameterizedType) genericType).getActualTypeArguments();
            if (actualTypes.length - 1 >= index) {
                Type actualType = actualTypes[index];
                if (actualType instanceof Class)
                    return (Class) actualType;
                else if (actualType instanceof ParameterizedType)
                    return (Class) ((ParameterizedType) actualType).getRawType();
                else if (actualType instanceof GenericArrayType) {
                    Type componentType = ((GenericArrayType) actualType).getGenericComponentType();
                    if (componentType instanceof Class)
                        return ArrayReflection.newInstance((Class) componentType, 0).getClass();
                }
            }
        }
        return null;
    }

    /**
     * Returns true if the field includes an annotation of the provided class
     * type.
     */
    public boolean isAnnotationPresent(Class<? extends java.lang.annotation.Annotation> annotationType) {
        return field.isAnnotationPresent(annotationType);
    }

    /**
     * Returns an array of {@link Annotation} objects reflecting all annotations
     * declared by this field, or an empty array if there are none. Does not
     * include inherited annotations.
     */
    public Annotation[] getDeclaredAnnotations() {
        java.lang.annotation.Annotation[] annotations = field.getDeclaredAnnotations();
        Annotation[] result = new Annotation[annotations.length];
        for (int i = 0; i < annotations.length; i++) {
            result[i] = new Annotation(annotations[i]);
        }
        return result;
    }

    /**
     * Returns an {@link Annotation} object reflecting the annotation provided,
     * or null of this field doesn't have such an annotation. This is a
     * convenience function if the caller knows already which annotation type
     * he's looking for.
     */
    public Annotation getDeclaredAnnotation(Class<? extends java.lang.annotation.Annotation> annotationType) {
        java.lang.annotation.Annotation[] annotations = field.getDeclaredAnnotations();
        if (annotations == null) {
            return null;
        }
        for (java.lang.annotation.Annotation annotation : annotations) {
            if (annotation.annotationType().equals(annotationType)) {
                return new Annotation(annotation);
            }
        }
        return null;
    }

    /** Returns the value of the field on the supplied object. */
    public Object get(Object obj) throws ReflectionException {
        try {
            return field.get(obj);
        } catch (IllegalArgumentException e) {
            throw new ReflectionException("Object is not an instance of " + getDeclaringClass(), e);
        } catch (IllegalAccessException e) {
            throw new ReflectionException("Illegal access to field: " + getName(), e);
        }
    }

    /** Sets the value of the field on the supplied object. */
    public void set(Object obj, Object value) throws ReflectionException {
        try {
            field.set(obj, value);
        } catch (IllegalArgumentException e) {
            throw new ReflectionException("Argument not valid for field: " + getName(), e);
        } catch (IllegalAccessException e) {
            throw new ReflectionException("Illegal access to field: " + getName(), e);
        }
    }

}