First Test: the library BCEL and Javassist are involved in this test; javassist has been used in its two different forms: high level with source compilation, and low level with instruction manual insertion. Both BCEL and JDasm are used to low level manipulate the bytecode.
The test has been performed on a laptop Centrino 1600 Mhz with 512 Mb of ram.
The main purpose was to create an Hallo World class from scratch by using the library's api: here's the code of the four Hallo World class builder:

• BCEL: BCEL_HelloWorldBuilder.java
• Javassist with high level api: JAVASSIST_HelloWorldBuilder.java
• Javassist with low level api: JAVASSIST_HelloWorldBuilder2.java
• JDasm: JDASM_HelloWorldBuilder.java

The class created from scratch will be similiar to this and its structure will have:

• an empty constructor with local variable attribute
• a public static main method, which asks for a name and prints it: the asking part is protected by a try-block. The method has a local variable attribute
• a source file attribute

The result of the creation is an equal class in each case but the low level implementation of javassist: we were unable to add the local variable attribute to the code of the main method. Nevertheless such attribute is created and added to the method.

BCEL	Javassist high level	Javassist low level	JDasm