本文用英文寫的，主要是考慮到本文分享的內容即使在google上也搜索不到（至少我是沒有搜索到）。

My English is at a very low level, don't care about this fact, just focus on the idea shared here.

The idea comes from the source code of ConfigurationElement which is located in package org.eclipse.core.internal.registry, If you read through the source code, you can also get it. But I found there is no documentation about this topic, so I wrote this.

Sometimes we need to contribute java class to a extension point. And we can use ConfigurationElement#
createExecutableExtension(String attributeName) to create an instance of it, if such a class is just a normal class, eclipse will  call class#newInstance(). But there is obvious restriction for using this approach, can't pass parameter in to create instance for example.

There are three different way how eclipse create instance of your class.

1. normal, call class#newInstance()
2. if your calss implements IExecutableExtension interface, IExecutableExtension#setInitializationData(IConfigurationElement config, String propertyName, Object data) will be called on the instance returned by class#newInstance()
3. if your calss implements IExecutableExtensionFactory interface, IExecutableExtensionFactory#create() will be called

When you use the second method or the third method, you can pass in parameters, check the source code of ConfigurationElement, you will know how to do that. :D forgive me, I'm lazy.