Java Class New Instance newInstance(Class theClass, Class[] parameterTypes, Object[] initargs)

Description

Create an object of the given class.

License

Apache License

Parameter

Parameter	Description
theClass	a parameter
parameterTypes	an array of parameterTypes for the constructor
initargs	the list of arguments for the constructor

Declaration

public static <T> T newInstance(Class<T> theClass,
        Class<?>[] parameterTypes, Object[] initargs) 

Method Source Code

//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.lang.reflect.Constructor;

public class Main {
    /**
     * Create an object of the given class.
     * @param theClass
     * @param parameterTypes
     *          an array of parameterTypes for the constructor
     * @param initargs
     *          the list of arguments for the constructor
     */
    public static <T> T newInstance(Class<T> theClass,
            Class<?>[] parameterTypes, Object[] initargs) {
        // Perform some sanity checks on the arguments.
        if (parameterTypes.length != initargs.length) {
            throw new IllegalArgumentException(
                    "Number of constructor parameter types doesn't match number of arguments");
        }
        for (int i = 0; i < parameterTypes.length; i++) {
            Class<?> clazz = parameterTypes[i];
            if (!(clazz.isInstance(initargs[i]))) {
                throw new IllegalArgumentException("Object : "
                        + initargs[i] + " is not an instance of " + clazz);
            }
        }

        try {
            Constructor<T> meth = theClass
                    .getDeclaredConstructor(parameterTypes);
            meth.setAccessible(true);
            return meth.newInstance(initargs);
        } catch (Exception e) {
            throw new RuntimeException("Unable to instantiate "
                    + theClass.getName(), e);
        }
    }
}

Related

1. newInstance(Class targetType, String className, ClassLoader loader)
2. newInstance(Class tClass, Object... initargs)
3. newInstance(Class theClass)
4. newInstance(Class theClass)
5. newInstance(Class theClass)
6. newInstance(Class theClass, Object... initArgs)
7. newInstance(Class theClass, String className)
8. newInstance(Class theCls)
9. newInstance(Class type)