com.xenoamess.commons.as_final_field.AsFinalFieldUtils Maven / Gradle / Ivy
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/*
* MIT License
*
* Copyright (c) 2019 XenoAmess
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package com.xenoamess.commons.as_final_field;
import java.lang.reflect.Field;
import static com.xenoamess.commons.as_final_field.AsFinalFieldExceptionType.*;
/**
* AsFinalFieldUtils class.
*
* @author XenoAmess
* @version 0.6.0
*/
public class AsFinalFieldUtils {
/**
* Check if object.fieldName is null.
* If it is null, then set it to a new value.
* Otherwise throw an AsFinalFieldReSetException.
*
* if object is a Class, then will look into the class's static fields instead,
* but not the fields in the class object.
*
* If this field is not an AsFinalField, then do no check and set it to newValue directly.
*
* @param object the object that hold an AsFinalField field.
* @param fieldName fieldName that represent an AsFinalField field in object.
* @param newValue the new value of the AsFinalField field.
* @see AsFinalField
* @see AsFinalFieldReSetException
*/
public static void asFinalFieldSet(Object object, String fieldName, Object newValue) {
asFinalFieldSet(object, fieldName, null, newValue);
}
/**
* Check if object.fieldName is emptyValue.
* If it is emptyValue, then set it to a new value.
* Otherwise throw an AsFinalFieldReSetException.
*
* if object is a Class, then will look into the class's static fields instead,
* but not the fields in the class object.
*
* If this field is not an AsFinalField, then do no check and set it to newValue directly.
*
* @param object the object that hold an AsFinalField field.
* @param fieldName fieldName that represent an AsFinalField field in object.
* @param emptyValue the value that thought be empty by that type.
* @param newValue the new value of the AsFinalField field.
* @param a T object.
* @see AsFinalField
* @see AsFinalFieldReSetException
*/
public static void asFinalFieldSet(Object object, String fieldName, T emptyValue, T newValue) {
if (fieldName == null) {
throw new IllegalArgumentException("The object must not be null");
}
Field field;
try {
if (object instanceof Class) {
field = ((Class) object).getDeclaredField(fieldName);
} else {
field = object.getClass().getDeclaredField(fieldName);
}
} catch (NoSuchFieldException e) {
throw new AsFinalFieldReSetException(object, fieldName, FIELD_NOT_EXIST);
} catch (SecurityException e) {
throw new AsFinalFieldReSetException(object, fieldName, ILLEGAL_ACCESS);
}
try {
field.setAccessible(true);
Object fieldValue = field.get(object);
if (field.getDeclaredAnnotation(AsFinalField.class) == null || fieldValue == emptyValue) {
if (object instanceof Class) {
field.set(null, newValue);
} else {
field.set(object, newValue);
}
} else {
throw new AsFinalFieldReSetException(object, field, ALREADY_HAVE_VALUE);
}
} catch (IllegalAccessException | SecurityException e) {
throw new AsFinalFieldReSetException(object, field, ILLEGAL_ACCESS);
}
}
}