java - Getting Null pointer exception when returning from mysql query -

controller class call:

list<foo> foolist   = foodao.getfoolist(string.valueof(branchid),customerid,string.valueof(systemindex)); 

dao class method gets invoked:

public list<foo> getfoolist(string index_branch,string index_cust,string index_sys)  {    // object[] helo= new object[10];    system.out.println("branchid -> " +index_branch+ "customerid -> " +index_cust+ " systemid -> " +index_sys);    return db.query("select * tb_foo branch=? , customer=? , system=?",new rowmapper<foo>() {    @override    public foo maprow(resultset rs, int i) throws sqlexception {         foo foo = new foo();         foo.setpi(rs.getint("foo_pi"));         foo.setindex(rs.getint("foo_index"));         foo.setfooname(rs.getstring("foo_name"));         foo.setfoovalue(""+rs.getint("foo_value"));         return foo;          }     },index_branch,index_cust,index_sys);  } 

query when provided using commandline client returns list of values database, rowmapper not returning. checked if foodao returning null, wasn't. getting null pointer exception on line return db.query(...);

not sure question but,

place breakpoint @

db.query(...);

, check db not null