If you want the quest0 to be enclosed with CDATA markup, then create a CDATA content item:
Change the section:
if(ques.getName().equalsIgnoreCase("question")){
//read
System.out.println(ques.getTextTrim());
//write
ques.setText("question"+a);
}
to look like:
if(ques.getName().equalsIgnoreCase("question")){
//read
System.out.println(ques.getTextTrim());
//write
ques.removeContent();
ques.addContent(new CDATA("question"+a));
}