Click here to close now.


Java IoT Authors: Elizabeth White, Pat Romanski, Flint Brenton, Liz McMillan, Jennifer Gill

Related Topics: Java IoT

Java IoT: Article


Resizing windows

This article presents a Java/Swing component implementation of a feature that is ubiquitous in nearly all desktop applications, particularly Windows applications - an area in the lower right portion of a window (Frame) that can be used to resize the window.

Of course, a window can be re-sized with most desktop managers by dragging the lower-right edge - the additional component simply serves as a visual indicator of the resize capability, and also increases the margin of error for the mouse drag.

Typically this component is placed in a status or message area at the bottom of a window. I demonstrate my solution in the context of a very simple (and barely func-tional) Web browser. I also introduce a technique in which a Frame/JFrame/JInternalFrame can exhibit "continuous layout" behavior as it is resized.

The component is called Frame-Resizer. It subclasses JComponent and has two main jobs that it performs. First, it draws itself and, second, it handles mouse events so that it can both change the mouse cursor (on mouse enter/leave) and resize the window (on mouse press/drag/release). FrameResizer can be used to resize a Frame, JFrame, or JInternalFrame, each of which has a common ancestor of java.awt.Container in the component class hierarchy. So constructors for FrameResizer take a Container argument as follows:

public FrameResizer(Container parent);
public FrameResizer(Container parent, boolean useContinuousLayout);

Figure 1 shows the FrameResizer in its typical context, at the lower right edge of a window, as part of a status/message area.

FrameResizer draws itself in the paintComponent() method as shown in Listing 1. There are seven "ribs" that make up the component.

A rib is one of the raised "bumps" in the component visual; it's actually just two 2x2 pixel rectangles drawn in different colors offset slightly from each other. You can see this in the exploded view of the FrameResizer in Figure 2.

Much of the interesting FrameResizer code is in the MouseInputListener inner class that the component adds to itself. In the mouseEntered() and mouseExited() methods, the cursor is changed to Cursor.NW_RESIZE_CURSOR and the default Cursor, respectively. In the mousePressed() method (see Listing 2), the mouse location is converted to actual screen coordinates, and the relative location from edge of the window (the Point mouseAdjust) is calculated.

In the mouseDragged() method (see Listing 3), the current mouse position is again converted to absolute screen position, and the new bounds of the parent Container (Frame/InternalFrame) are recalculated based on the original mouse location.

The mouseReleased() method calls mouseDragged() for a final calculation, and then "validates" the parent container. Since FrameResizer supports either an external Frame or a JInternalFrame, the validate() method does the appropriate validation and invokes the repaint() method (see Listing 4). This needs to be done at the end of the AWT EventDispatchThread (thus the use of SwingUtilities.invokeLater()). This method is declared static so it can be re-used for the "continuous layout" functionality (see below).

Continuous Layout
This concept is familiar to Swing developers who use JSplitPane - it's the ability to have internal components validate and repaint as the container is resized (in real time). Unfortunately, when a top-level Java desktop window is resized, this doesn't happen, as the validate/repaint messages are not sent to the underlying Container until resizing (via mouse dragging) is complete. Figure 3 is a capture of our browser window during the mouse drag. You can see how the contents of the window are not "stretched' to fit the bounds of the Frame - this is done when the mouse is released.

Ideally you want the contents of the window to stretch to the frame bounds during resizing. This capability is evident in most non-Java top-level desktop windows.

The trick to doing this in Java is to use a Timer to periodically check the current bounds of the window (Frame), and if it has changed since the last interval, send the validate/repaint messages to the Frame. You can see how this is done in Listing 5. I coded it as a static method in FrameResizer so this functionality can be used independently of the component.

The code uses a static HashMap (continuousLayoutWindows) so it can be used for multiple windows in a multi-frame application. It lazily initializes this HashMap. In the map it stores the current Container bounds keyed by the Container. If the current bounds are different than what is in the map, the current bounds are saved and the validate and repaint messages are sent to the Container (our static validate() method from before). That's all there is to it. I use 100 milliseconds (hard-coded) as my timer interval - feel free to experiment with this number (or parameterize it).

You can specify whether or not "continuous layout" is used by the FrameResizer in its constructor (the default is true). Note that one drawback to "continuous layout" in this context is the flicker that occurs during the repaint. This is unfortunately unavoidable. Also note that the continuous layout behavior is not required if you are using the FrameResizer in the context of a JInternalFrame.

In this article I presented a custom Swing component that can be used to help provide a customary look and feel to a Frame or JInternalFrame. I've also introduced the concept of "continuous layout" to top-level Java desktop windows and shown how this can be implemented. The source code for this article can be downloaded from

More Stories By Phil Herold

Phil Herold is VP and CTO of PocketScience LLC in Research Triangle Park, NC. He has over 24 years of experience in software engineering, and has been working with Java client technologies since 1996.

Comments (4) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.

Most Recent Comments
Phil Herold 09/28/05 10:43:13 AM EDT

The link for the code to this article has been fixed. Here's the direct link:

This contains a jar file with both source and class files. If your run the jar with javaw, it will run the "Lame Browser" window that is shown in the article.

Phil Herold 09/26/05 09:59:47 AM EDT


Someone in a private e-mail pointed out that Toolkit.setDynamicLayout() will accomplish the same thing as the timer/validate-paint technique used in my article. I haven't tried it, but you might look at that as well.

Michael Bushe 08/12/05 08:05:03 PM EDT

Brilliant!!! I've been writing fancy Swing apps for a long time and never even considered that there was a way around the gray-screen-as-you-resize problem. Very slick, very thorough. An icon for this was meticulously created by Jonathan Simon here:

Bill Winspur 08/12/05 06:10:43 PM EDT

Very interesting article - unfortunately I cant find a link to the source code in the article, or on . Can somebody provide it?

@ThingsExpo Stories
Continuous processes around the development and deployment of applications are both impacted by -- and a benefit to -- the Internet of Things trend. To help better understand the relationship between DevOps and a plethora of new end-devices and data please welcome Gary Gruver, consultant, author and a former IT executive who has led many large-scale IT transformation projects, and John Jeremiah, Technology Evangelist at Hewlett Packard Enterprise (HPE), on Twitter at @j_jeremiah. The discussion is moderated by me, Dana Gardner, Principal Analyst at Interarbor Solutions.
With all the incredible momentum behind the Internet of Things (IoT) industry, it is easy to forget that not a single CEO wakes up and wonders if “my IoT is broken.” What they wonder is if they are making the right decisions to do all they can to increase revenue, decrease costs, and improve customer experience – effectively the same challenges they have always had in growing their business. The exciting thing about the IoT industry is now these decisions can be better, faster, and smarter. Now all corporate assets – people, objects, and spaces – can share information about themselves and thei...
Too often with compelling new technologies market participants become overly enamored with that attractiveness of the technology and neglect underlying business drivers. This tendency, what some call the “newest shiny object syndrome” is understandable given that virtually all of us are heavily engaged in technology. But it is also mistaken. Without concrete business cases driving its deployment, IoT, like many other technologies before it, will fade into obscurity.
The Internet of Things is clearly many things: data collection and analytics, wearables, Smart Grids and Smart Cities, the Industrial Internet, and more. Cool platforms like Arduino, Raspberry Pi, Intel's Galileo and Edison, and a diverse world of sensors are making the IoT a great toy box for developers in all these areas. In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists discussed what things are the most important, which will have the most profound effect on the world, and what should we expect to see over the next couple of years.
Discussions of cloud computing have evolved in recent years from a focus on specific types of cloud, to a world of hybrid cloud, and to a world dominated by the APIs that make today's multi-cloud environments and hybrid clouds possible. In this Power Panel at 17th Cloud Expo, moderated by Conference Chair Roger Strukhoff, panelists addressed the importance of customers being able to use the specific technologies they need, through environments and ecosystems that expose their APIs to make true change and transformation possible.
Microservices are a very exciting architectural approach that many organizations are looking to as a way to accelerate innovation. Microservices promise to allow teams to move away from monolithic "ball of mud" systems, but the reality is that, in the vast majority of organizations, different projects and technologies will continue to be developed at different speeds. How to handle the dependencies between these disparate systems with different iteration cycles? Consider the "canoncial problem" in this scenario: microservice A (releases daily) depends on a couple of additions to backend B (re...
Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world. Get ready to learn the facts: Is there a bias against women in the tech / developer communities? Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions? Some beginnings of what to do about it! In her Day 2 Keynote at 17th Cloud Expo, Sandy Carter, IBM General Manager Cloud Ecosystem and Developers, and a Social Business Evangelist, wil...
PubNub has announced the release of BLOCKS, a set of customizable microservices that give developers a simple way to add code and deploy features for realtime apps.PubNub BLOCKS executes business logic directly on the data streaming through PubNub’s network without splitting it off to an intermediary server controlled by the customer. This revolutionary approach streamlines app development, reduces endpoint-to-endpoint latency, and allows apps to better leverage the enormous scalability of PubNub’s Data Stream Network.
The cloud. Like a comic book superhero, there seems to be no problem it can’t fix or cost it can’t slash. Yet making the transition is not always easy and production environments are still largely on premise. Taking some practical and sensible steps to reduce risk can also help provide a basis for a successful cloud transition. A plethora of surveys from the likes of IDG and Gartner show that more than 70 percent of enterprises have deployed at least one or more cloud application or workload. Yet a closer inspection at the data reveals less than half of these cloud projects involve production...
Apps and devices shouldn't stop working when there's limited or no network connectivity. Learn how to bring data stored in a cloud database to the edge of the network (and back again) whenever an Internet connection is available. In his session at 17th Cloud Expo, Ben Perlmutter, a Sales Engineer with IBM Cloudant, demonstrated techniques for replicating cloud databases with devices in order to build offline-first mobile or Internet of Things (IoT) apps that can provide a better, faster user experience, both offline and online. The focus of this talk was on IBM Cloudant, Apache CouchDB, and ...
Container technology is shaping the future of DevOps and it’s also changing the way organizations think about application development. With the rise of mobile applications in the enterprise, businesses are abandoning year-long development cycles and embracing technologies that enable rapid development and continuous deployment of apps. In his session at DevOps Summit, Kurt Collins, Developer Evangelist at, examined how Docker has evolved into a highly effective tool for application delivery by allowing increasingly popular Mobile Backend-as-a-Service (mBaaS) platforms to quickly crea...
I recently attended and was a speaker at the 4th International Internet of @ThingsExpo at the Santa Clara Convention Center. I also had the opportunity to attend this event last year and I wrote a blog from that show talking about how the “Enterprise Impact of IoT” was a key theme of last year’s show. I was curious to see if the same theme would still resonate 365 days later and what, if any, changes I would see in the content presented.
Cloud computing delivers on-demand resources that provide businesses with flexibility and cost-savings. The challenge in moving workloads to the cloud has been the cost and complexity of ensuring the initial and ongoing security and regulatory (PCI, HIPAA, FFIEC) compliance across private and public clouds. Manual security compliance is slow, prone to human error, and represents over 50% of the cost of managing cloud applications. Determining how to automate cloud security compliance is critical to maintaining positive ROI. Raxak Protect is an automated security compliance SaaS platform and ma...
Internet of @ThingsExpo, taking place June 7-9, 2016 at Javits Center, New York City and Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 18th International @CloudExpo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world and ThingsExpo New York Call for Papers is now open.
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo 2016 in New York and Silicon Valley. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place Nov 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 17th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound cha...
We are rapidly moving to a brave new world of interconnected smart homes, cars, offices and factories known as the Internet of Things (IoT). Sensors and monitoring devices will touch every part of our lives. Let's take a closer look at the Internet of Things. The Internet of Things is a worldwide network of objects and devices connected to the Internet. They are electronics, sensors, software and more. These objects connect to the Internet and can be controlled remotely via apps and programs. Because they can be accessed via the Internet, these devices create a tremendous opportunity to inte...
Today air travel is a minefield of delays, hassles and customer disappointment. Airlines struggle to revitalize the experience. GE and M2Mi will demonstrate practical examples of how IoT solutions are helping airlines bring back personalization, reduce trip time and improve reliability. In their session at @ThingsExpo, Shyam Varan Nath, Principal Architect with GE, and Dr. Sarah Cooper, M2Mi’s VP Business Development and Engineering, explored the IoT cloud-based platform technologies driving this change including privacy controls, data transparency and integration of real time context with p...
We all know that data growth is exploding and storage budgets are shrinking. Instead of showing you charts on about how much data there is, in his General Session at 17th Cloud Expo, Scott Cleland, Senior Director of Product Marketing at HGST, showed how to capture all of your data in one place. After you have your data under control, you can then analyze it in one place, saving time and resources.
The Internet of Things (IoT) is growing rapidly by extending current technologies, products and networks. By 2020, Cisco estimates there will be 50 billion connected devices. Gartner has forecast revenues of over $300 billion, just to IoT suppliers. Now is the time to figure out how you’ll make money – not just create innovative products. With hundreds of new products and companies jumping into the IoT fray every month, there’s no shortage of innovation. Despite this, McKinsey/VisionMobile data shows "less than 10 percent of IoT developers are making enough to support a reasonably sized team....
Just over a week ago I received a long and loud sustained applause for a presentation I delivered at this year’s Cloud Expo in Santa Clara. I was extremely pleased with the turnout and had some very good conversations with many of the attendees. Over the next few days I had many more meaningful conversations and was not only happy with the results but also learned a few new things. Here is everything I learned in those three days distilled into three short points.