Java Class Load loadClass(String classname, Class clazz)

Description

Tries to load the class from the current thread's context class loader.

License

Open Source License

Parameter

Parameter	Description
classname	Desired class.
clazz	Class object used to obtain a class loader if no context class loader is available.

Return

Class, or null on failure.

Declaration

public static Class loadClass(String classname, Class clazz) throws ClassNotFoundException 

Method Source Code

//package com.java2s;
/*/*from w  ww  .j a  va  2 s . co  m*/
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/

public class Main {
    /**
     * Tries to load the class from the current thread's context class loader. If
     * not successful, tries to load the class from the current instance.
     *
     * @param classname Desired class.
     * @param clazz     Class object used to obtain a class loader
     *                  if no context class loader is available.
     * @return Class, or null on failure.
     */
    public static Class loadClass(String classname, Class clazz) throws ClassNotFoundException {
        ClassLoader loader;

        try {
            loader = Thread.currentThread().getContextClassLoader();
            if (loader != null) {
                return Class.forName(classname, false, loader);
            }
        } catch (Throwable t) {
        }

        if (clazz != null) {
            try {
                loader = clazz.getClassLoader();
                if (loader != null) {
                    return Class.forName(classname, false, loader);
                }
            } catch (Throwable t) {
            }
        }

        try {
            loader = ClassLoader.getSystemClassLoader();
            if (loader != null) {
                return Class.forName(classname, false, loader);
            }
        } catch (Throwable t) {
        }

        throw new ClassNotFoundException(classname);
    }

    /**
     * Tries to load the class from the passed class' classloader, then current thread's context class loader.
     *
     * @param clazz     Class object used to obtain a class loader
     *                  if no context class loader is available.
     * @param classname Desired class.
     * @return Class, or null on failure.
     */
    public static Class loadClass(Class clazz, String classname) throws ClassNotFoundException {
        ClassLoader loader;

        if (clazz != null) {
            try {
                loader = clazz.getClassLoader();
                if (loader != null) {
                    return Class.forName(classname, false, loader);
                }
            } catch (Throwable t) {
            }
        }

        try {
            loader = Thread.currentThread().getContextClassLoader();
            if (loader != null) {
                return Class.forName(classname, false, loader);
            }
        } catch (Throwable t) {
        }

        try {
            loader = ClassLoader.getSystemClassLoader();
            if (loader != null) {
                return Class.forName(classname, false, loader);
            }
        } catch (Throwable t) {
        }

        throw new ClassNotFoundException(classname);
    }
}

Related

1. loadClass(String className)
2. loadClass(String className)
3. loadClass(String className, boolean isInitialized)
4. loadClass(String className, Class callingClass)
5. loadClass(String classname, Class clazz)
6. loadClass(String classname, Class clazz)
7. loadClass(String className, Class context, boolean checkParent)
8. loadClass(String className, Class ofType)
9. loadClass(String className, Class targetType, ClassLoader cl)