geojson editing and reading, pretend I'm a noob

Question

right now I'm working on a project where I'm trying to visualize internet coverage in new york city. I've downloaded the fcc's csv that details the internet coverage of the united states and parsed through it using java to get all of the data that's only pertaining to new york city. I did that by only choosing data rows that contained the proper census codes of the 5 new york city counties (the five boroughs). Here's the problem. The only geographically linked data that the fcc's csv has is the census codes, and right now, I'm having trouble linking the data to geographic locations on a map. I have a geojson file that has the geodata that goes with each census code in nyc, but I don't know how to parse and edit geojson files in java. This is the format of the geojson I have:

{
   "type": "FeatureCollection",
   "features": [
      {
         "type": "Feature",
         "id": 0,
         "properties": {
            "OBJECTID": 2038,
            "STATEFP": "36",
            "COUNTYFP": "081",
            "TRACTCE": "014000",
            "BLKGRPCE": "1",
            "GEOID": "360810140001",
            "NAMELSAD": "Block Group 1",
            "MTFCC": "G5030",
            "FUNCSTAT": "S",
            "ALAND": 113131,
            "AWATER": 0,
            "INTPTLAT": "+40.7030341",
            "INTPTLON": "-073.8279064",
            "geo_id": "15000US360810140001",
            "OBJECTID_1": 10466,
            "GEOID_1": "15000US360810140001",
            "SHAPE_Leng": 0.02086447918,
            "SHAPE_Area": 0.00001205464
         },
         "geometry": {
            "type": "Polygon",
            "coordinates": [
               [
                  [
                     -73.82266,
                     40.703585
                  ],
                  [
                     -73.83152,
                     40.70139
                  ],
                  [
                     -73.83213,
                     40.702794
                  ],
                  [
                     -73.82576,
                     40.704428
                  ],
                  [
                     -73.82246,
                     40.703656
                  ],
                  [
                     -73.82266,
                     40.703585
                  ]
               ]
            ]
         }
      },

The way I imagine doing this is by selecting the first geojson object, and then using that code to search through the csv, or by selecting the first csv line, and then searching for the same census code in my geojson. That way is obviously really inefficient. Is a better solution to somehow sort the csv based on the numerical value of the census code, and then read down starting with geojson? If the csv is ordered, I can write a binary search algorithm to do that.

To sum it up: I need help with ordering a csv based on one column's numerical value, and help with reading and editing a geojson file. I would appreciate all help.

Here is the code I was trying to use to pair the values (I had converted the geojson to csv, but I found that when converting from csv to geojson, no online code I have found to do so works correctly.

public static void main(String args[]) throws FileNotFoundException{
  // Construct a BufferedReader object from the input file
    BufferedReader r = new BufferedReader(new FileReader("newyorkcitydistilled.csv"));
    BufferedReader cs = new BufferedReader(new FileReader("convertcsv.csv"));
    String[] linedata;
    String[] linedata2;
    PrintWriter pw = new PrintWriter(new File("nycdistilledgeo2.csv"));
    String line;
    String line2;
    int it = 0;
  try{
//prime the geodata

//NOTE TO SELF!!! THE CSV FOR CONVERT NEETS TO BE REFORMATTED BECAUSE OF THE FIRST THREE COLUMNS
      line2 = cs.readLine();
      linedata2 = line2.split(",(?=(?:[^\"]*\"[^\"]*\")*[^\"]*$)", -1);

    while ((line = r.readLine()) != null) {
          if (line.isEmpty()) {
              break;}
          it++;
          if(it % 100 == 0)
          System.out.println(it);
          linedata = line.split(",(?=(?:[^\"]*\"[^\"]*\")*[^\"]*$)", -1);
      //    System.out.print(line2);
//while the two lines being looked at dont fit the matching criteria, keep looking through the convertcsv
      while((boroComp(linedata[9].substring(2,5),linedata2[4].substring(0,1)) && linedata[9].substring(5,15).equals(linedata2[4].substring(1,11))) == false){
            line2 = cs.readLine();
            try{
            linedata2 = line2.split(",(?=(?:[^\"]*\"[^\"]*\")*[^\"]*$)", -1);
        //    System.out.println(linedata2[4]);
          }catch(NullPointerException e){
        //    System.out.println("caught");
            break;
          }
            //somehow before it hits the last line of the csv, it needs to just say no match and move on

//need to restart the progress on readline for CS every time a correct comparison is made
        }
      //  System.out.println("not broken");
//if it is true, add the new line in
    //  System.out.println(line2);
  //    System.out.println(linedata2[0] + "," + linedata2[1] + "," + linedata2[2] + "," + linedata2[5]);
      //  System.out.println(line + linedata2[0] + linedata2[1] + linedata2[2] + linedata2[5]);
        pw.write(line + "," + linedata2[0] + "," + linedata2[1] + "," + linedata2[2] + "," + linedata2[5] + "\n");
//reset the buffered reader
        cs.close();
        cs = new BufferedReader(new FileReader("convertcsv.csv"));
//reprime the String
        line2 = cs.readLine();
        linedata2 = line2.split(",(?=(?:[^\"]*\"[^\"]*\")*[^\"]*$)", -1);
      }
        r.close();
        cs.close();
}
catch( IOException ioException ) {
    System.out.println("Exception: "+ioException);
}

pw.flush();
}
}

Here's a line of my csv data, sorted from the fcc