java - how can i create a JSON object from different tables( MySQL database) to consume in android project? -

this api. how can have results converted json object using java?

$sql1="select s.* , c.*,u.*         schedule_ s,course_t c, u user_t         c.course_crn=p.course_crn , s.teacher_id=u.employee_id" ;  $result=mysqli_query($con,$sql1);    if($result) {    while($row=mysqli_fetch_array($result))  {   $data[]=$row;   }     print(json_encode($data)); 

you need following

load mysql driver:

    class.forname("com.mysql.jdbc.driver"); // need include , load jdbc driver 

create connection credentials, host , port:

    string url = "jdbc:mysql://mysql_host:mysql_port/mysql_db";     string user = "mysql_user";     string pass = "mysql_pass";     connection conn = drivermanager.getconnection(url, user, pass); 

execute sql query:

    string sql = "select s.* , c.*,u.* schedule_ s,course_t c, u user_t c.course_crn=p.course_crn , s.teacher_id=u.employee_id;";     preparedstatement preparedstatement = conn.preparestatement(sql);     resultset result = preparedstatement.executequery(); 

build object:

    list<hashmap<string, object>> rows = new arraylist<hashmap<string, object>>();      resultsetmetadata md = result.getmetadata();     int columns = md.getcolumncount();     while (result.next()) {         hashmap<string, object> row = new hashmap<>();         (int = 1; <= columns; ++i) {             row.put(md.getcolumnname(i), result.getobject(i));         }         rows.add(row);     } 

then can convert json java object using gson:

    string json = new gson().tojson(rows); // can use gson google build json     system.out.println(json);