Here you can find the source of setFieldValue(Object object, String fieldName, Object fieldValue)
public static void setFieldValue(Object object, String fieldName, Object fieldValue) throws IOException
//package com.java2s; /**/*from www.j a v a 2 s . c o m*/ * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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. */ import java.io.IOException; import java.lang.reflect.Field; public class Main { public static void setFieldValue(Object object, String fieldName, Object fieldValue) throws IOException { try { if (object instanceof Class) getField((Class<?>) object, fieldName).set(null, fieldValue); else getField(object.getClass(), fieldName).set(object, fieldValue); } catch (Throwable t) { throw new IOException(t); } } public static Field getField(Class<?> clazz, String fieldName) throws IOException { if (clazz == null) throw new IOException("clazz is null"); if (fieldName == null) throw new IOException("fieldName is null"); if (fieldName.isEmpty()) throw new IOException("fieldName is empty"); Field field = null; try { field = clazz.getDeclaredField(fieldName); } catch (Throwable t0) { try { field = clazz.getField(fieldName); } catch (Throwable t1) { if (clazz.getSuperclass() != null) { field = getField(clazz.getSuperclass(), fieldName); } else throw new IOException("fail to get field for " + clazz.getName() + "." + fieldName, t1); } } field.setAccessible(true); return field; } }