Need help in generating an instruction list

Can someone tell me how to generate the code pasted below, I have to
generate a similar, but much more complex code...

try{

		ClassParser parser = new ClassParser(filename);
	    JavaClass java_class = parser.parse();

	    Method[] methods = java_class.getMethods();
	    ConstantPool cp = java_class.getConstantPool();
      	Constant[] clist = cp.getConstantPool();


      	for(int k=0; k<clist.length; k++) {
	      	if(clist[k] instanceof ConstantString) {
				ConstantString cName =
(ConstantString)clist[k];
				String cName1 = cName.getBytes(cp);
				//System.out.println(cName1);
				byte[] b = cName1.getBytes();
				for (int i=0; i<b.length; i++)
					b[i]^=2;
				cName1 = new String(b);
				//System.out.println(cName1);
				//cName = cName1;
				Constant cNew = new ConstantUtf8(cName1);
				clist[k] = cNew;
			}
	    }
	    }
	    catch(Exception e){
	    	System.out.println(e);
	    }

Maithily Mundle,
CS Department,
OSU.