java - JSON Processing using Jackson 2.2 -

i using jackson 2.2 read large json string java object. using objectmapper, read memory , transform json string object. happening in memory, entire json string loaded memory , transformed object.

if there more memory efficient way of doing it? i.e. without loading entire json string memory, should still able load object.

yes, typically use so-called "streaming" api iterate on json tokens; , once positioned on first token of value want (start_object json objects), use data-binding api, passing reader/parser use. details of depend on library. know @ least following support mode of operation:

• jackson
• gson
• genson

for jackson, basic streaming api usage talked here (for example); 1 thing not show how bind objects once positioned @ right place. assuming json like:

{ "comment" : "...",   "values" : [      { ... value object 1 ... },      { ... value object 2. ... }   ] } 

you do:

objectmapper mapper = new objectmapper(); jsonparser jp = mapper.getfactory().createjsonparser(jsoninput); jp.nexttoken(); // return start_object, may want verify while (jp.nextvalue() != null) { // 'nextvalue' skips field_name token, if   string fieldname = jp.getcurrentname();   if ("values".equals(fieldname)) {     // yes, should point start_array     while (jp.nexttoken() == jsontoken.start_object) {       valueobject v = mapper.readvalue(jp, valueobject.class);       // process individual value in whatever way want to...     }   } else if ("comment".equals(fieldname)) {      // handle comment?   } // may use else catch unknown fields, if } jp.close(); 

and should let bind 1 object @ time.