How to tokenize Java String with nested square brackets?

Question

I have a string I would like to put into an ArrayList of Strings. The string is basically a JSONObject so I might just be using the wrong methods.

The way the string looks is:

String all = "{"users":
[
 [{"login":"username1"},{"password":"test1"},{"index":"1"}],
 [{"login":"username2"},{"password":"test2"},{"index":"2"}]
]}";

All I want is the JSONObject values so my pattern gives me this String:

String part = "[
                [{"login":"username1"},{"password":"test1"},{"index":"1"}],
                [{"login":"username2"},{"password":"test2"},{"index":"2"}]
               ]";

This is what I want:

user[0] = "[{"login":"username1"},{"password":"test1"},{"index":"1"}]";
user[1] = "[{"login":"username2"},{"password":"test2"},{"index":"2"}]";

When I try to group everything in between the inner [ ] it just returns everything in the outer [ ].

I have tried:

String[] user = new String[20];
Pattern p = Pattern.compile("(\\[\\{.*\\}\\])");
Matcher m = p.matcher(part);
while(m.find()){
    user = m.group().split("\\],\\[");
}

This approach gets rid of the ],[ which I'm using as a delimiter.

Don't try and create one with regex, just use an existing JSON or YAML library to parse your `String`. — Elliott Frisch, Dec 16 '14 at 04:55
From Java 8: http://www.oracle.com/technetwork/articles/java/json-1973242.html — nhahtdh, Dec 16 '14 at 05:05
Use a library to process json: http://stackoverflow.com/questions/27347763/looking-for-a-straightforward-way-to-parse-json — Bart Kiers, Dec 16 '14 at 06:12

score 0 · Answer 1 · answered Dec 16 '14 at 05:02

0

Class User {
  private String username;
  private String password;
}

Class Users{
  LinkedList<User> users;
}

You can use any available JSON marshallers like Jackson etc to deserialize the string into a Users.

answered Dec 16 '14 at 05:02

abhati

309
1
6

Kasper-34 · Accepted Answer · 2014-12-16T08:50:24.500

So I took the advice from the comment section and sure enough using JSON methods was the way to go. I would still like to see if it was possible to accomplish with regular expressions.

ArrayList<String> myList = new ArrayList<String>();
JSONObject obj = new JSONObject();
JSONArray arr = new JSONArray();

obj = {"user":"[[{},{},{}],[{},{},{}]]";

// This gives me the outer JSONArray    
arr = obj.getJSONArray("user");

// This iterates through the outer JSONArray assigning each inner JSONArray
// to my ArrayList as strings.
for( int i = 0; i < arr.length(); i++){
    myList.put(arr.getJSONArray(i).toString());
}

How to tokenize Java String with nested square brackets?

2 Answers2