There are now a lot of mobile and wireless devices that can connect to the Internet. Cell phones and PDAs are two of the most popular ones. So, in this paper, we'll talk about how to use design patterns and Java-based software components to make embedded software that runs on the two devices. Some parts can be used directly in an embedded software system, but most parts have to be changed before they can be used again. The developers have to figure out where these components differ. In order to make an embedded software system that can be used more than once, we will find a few variation points with some variants and talk about some useful design patterns that can be used to implement variation points. So, we can change the way an embedded software system works by attaching variants to the system's variation points. We use the property container, the strategy, the decorator, and the model-view-controller design patterns. J2ME is the technology we are using for the parts. J2ME is a specification for making apps for mobile devices. It provides a similar environment as standard Java environment. The Spotlet programming for the PDA and the MIDlet programming for the Java phone are both part of the components programming for J2ME. Along with XML, J2ME can also offer XMIDlet programming, which allows XML-based applications for PDAs and Java phones to be dynamically downloaded and run.