Java中如何从另一个类获取类的特定实例？

我创建了以下课程main方法，它创建新的实例Application和实例ApplicationModel, ApplicationView and ApplicationController对于这个特殊的Application.

public class Application
{

    // Variables

    private ApplicationSettings         settings;
    private ApplicationModel            model;
    private ApplicationView             view;
    private ApplicationController       controller;

    // Constructor

    public Application()
    {
        settings        = new ApplicationSettings();
        model           = new ApplicationModel();
        view            = new ApplicationView(model);
        controller      = new ApplicationController();
    }

    // Main method

    public static void main(String[] args)
    {
        Application application = new Application();
    }

    // Getters for settings, model, view, controller for instance of Application

}

我知道，永远只有一个独特的实例Application.

我想在我的中得到这个特定的实例ApplicationModel, ApplicationView and ApplicationController类。

这怎么可能？

我会在应用程序类上使用单例。

Put a public static方法返回您唯一的应用程序实例。

public class Application
{
    private Application() { } // make your constructor private, so the only war
                              // to access "application" is through singleton pattern

    private static Application _app;

    public static Application getSharedApplication() 
    {
        if (_app == null)
            _app = new Application();
        return _app;
    }
}

您可以阅读更多有关单例设计模式 here http://en.wikipedia.org/wiki/Singleton_pattern.

每当您需要唯一的时候Application例如，你这样做：

Application app = Application.getSharedApplication();