serializing java object to json with auto generated names -

i want create json file out of java objects similar structure:

{"users" :

 {"1" :       { "ids" : [1,2,3], "names" : ["anton","berta","charlie"] },   {"2" :      { "ids" : [4,5,6], "names" : ["dora","emil","friedrich"] }, 

...and on.

my problem don´t know how generate numbers of second hierarchy. in of tutorials found hierarchy names generated class names or annotations can´t use way create requested names.

is there way without writing huge method generate json stirng "by hand"?

greetz

the code required create each json entry not much:

public static string tojson(int i, list<user> users) {     stringbuilder sb = new stringbuilder("{\"").append(i).append("\" : { \"ids\" : [");     (user user : users)         sb.append(user.getid()).append(",");     sb.setcharat(sb.length() - 1, ']');     sb.append(", \"names\" : [\"");     (user user : users)         sb.append(user.getname()).append("\",\"");     return sb.replace(sb.length() - 2, sb.length(),"] } ,").tostring(); } 

with method in place, adding new users list during time period , assigning sequential number each list trivial matter.

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here's complete test code , output:

static class user {     private final int id;     private final string name;      public user(int id, string name) {         this.id = id;         this.name = name;     }      public int getid() {         return id;     }      public string getname() {         return name;     } }  public static string tojson(int i, list<user> users) {     stringbuilder sb = new stringbuilder("{\"").append(i).append("\" : { \"ids\" : [");     (user user : users)         sb.append(user.getid()).append(",");     sb.setcharat(sb.length() - 1, ']');     sb.append(", \"names\" : [\"");     (user user : users)         sb.append(user.getname()).append("\",\"");     return sb.replace(sb.length() - 2, sb.length(),"] } ,").tostring(); }  public static void main(string[] args) {//throws exception {     list<user> users = new arraylist<user>();     users.add(new user(1, "anton"));     users.add(new user(2, "berta"));     users.add(new user(3, "charlie"));     system.out.println(tojson(1, users));  } 

output:

{"1" : { "ids" : [1,2,3], "names" : ["anton","berta","charlie"] } ,