servi/org.eclipse.statet.rj.servi-tests/src/org/eclipse/statet/rj/servi/Accessor.java

/*=============================================================================#
 # Copyright (c) 2021 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.rj.servi;

import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;

import java.lang.reflect.Field;

import org.eclipse.statet.jcommons.lang.NonNullByDefault;
import org.eclipse.statet.jcommons.lang.Nullable;


@NonNullByDefault
public class Accessor {
	
	
	private Class<?> clazz;
	private final Object instance;
	
	
	public Accessor(final Object instance, final Class<?> clazz) {
		this.instance= nonNullAssert(instance);
		this.clazz= nonNullAssert(clazz);
	}
	
	public Accessor(final Object instance, final String className, final ClassLoader classLoader) {
		this.instance= nonNullAssert(instance);
		try {
			this.clazz= Class.forName(className, true, classLoader);
		}
		catch (ClassNotFoundException | ExceptionInInitializerError e) {
			throw new RuntimeException(e);
		}
	}
	
	
	public Field getField(final String fieldName) {
		try {
			final Field field= this.clazz.getDeclaredField(fieldName);
			field.setAccessible(true);
			return field;
		}
		catch (SecurityException | NoSuchFieldException e) {
			throw new RuntimeException(e);
		}
	}
	
	public @Nullable Object getFieldObj(final String fieldName) {
		try {
			final Field field= getField(fieldName);
			return field.get(this.instance);
		}
		catch (IllegalArgumentException | IllegalAccessException e) {
			throw new RuntimeException(e);
		}
	}
	
}