J2ME tips and tricks

[Gun-master]

Optimizing hash functions in J2ME

Least amount perfect hash maps do not necessitate any surplus memory, but may strength important expenditure on the map. Use a dissassembler (e.g. like javap) to determine which of various option coding formulations produces smaller bytecode. If size is a limit: use SDK classes wherever feasible; inherit whatever potential; put common code in one place; initialize big arrays at runtime by parsing a string; use little names. To reduce the number of class files and their sizes: use the SDK classes as much as possible; and implement common functionality in one place only.

MIDP tips for J2ME

First compose HTTP (Hyper Text Transfer Protocol) needs in a backdrop thread. Use an asynchronous messaging model for the MIDP. Then employ WBXML to constrict XML messages.

The smallest "Hello World"

The java complier will insert a default constructor if you do not create one in the program. A constructor is needed when you made a instances of it. Many of the variables and the class references used by the code generate entries in the constant pool. If you are using the existing pool entries for the variables or methods or class it will reduces the class file size.

[Gun-master]

Benchmarking

In J2ME program language, software accelerators may get better pace, but they may also put away extreme power compared to a processor that executes Java as its inhabitant language.

Mobile and wireless devices in J2ME

Wireless devices that are available in the J2ME are the Prototype to conclude the performance of your device. Wireless transmissions necessitate testing to resolve if the transfer rates and processing times are satisfactory. Effort to make applications that can complete 83% or more of their operations through the touch of a single key or button or the "tap" or touch of the stylus to the screen. Demanding to operate a very small scroll bar on a little screen can be a work out in hand-eye coordination. Straight scrolling should be avoided at all costs. Challenge to keep away from having the client bear in mind any data, or worse, having to evaluate data across screens. Performance is the most important features of the J2ME applications. Bring together the code with debugging information turned off using the -g: none switch, this increases performance and reduces its path. The important think that should be avoided is the deep hierarchies in your class structure. Believe third-party JVMs, many are faster than the Sun ones.

[Gun-master]

Minimizing byte code size for J2ME

The unnecessary features should must be eliminated from the code each time when you compile the code. The inner classes must be avoided, make the main class implement the required listener interfaces and then handle the callback there only. There should be use of the in-built classes to the maximum. All the name of the packages, classes, methods, data variables must be properly shorted in a sequential manner. Convert array initialization from the code to extract data from a binary string or the data file or directory.

MIDP GUI programming for the J2ME Applications

J2ME mobile application and the wireless application which require tall screen performance requires such as games wants finer manage over the MIDP screens and they must use the javax.microedition.lcdui package which provides the low level API for the handling such issues. Always verify the drawing area using the Canvas. All the devices not support the colors so it should be kept in mind at the time of programming. Many a time the alphanumeric data is entered from a handheld device which is a very difficult job in the J2ME programming. If there is a understanding of the byte code by the developer then the performance of the application can be increased.