How can I optimize this HashMap with 42,000 keys

Question

I have a csv file with 42,000 lines in the following pattern

03055,Milford,NH
03057,Mont Vernon,NH
03060,Nashua,NH

I tried to store the data in a HashMap using the zipcode as a key, like

while ((line = stream_in.readLine())!=null) {
    LocationBean temp_location_bean = new LocationBean();
    String line_trimmed = line.trim();
    String[] line_chunked = line_trimmed.split(",",4);
    temp_location_bean.setZip_code(line_chunked[0]);
    temp_location_bean.setCity(line_chunked[1]);
    temp_location_bean.setState(line_chunked[2]);
    this.locations_as_beans_list.put(zip_code, temp_location_bean);
}

But when I go to do a lookup:

 for(Map.Entry<String, LocationBean> location_object : this.locations_as_beans_list.entrySet())
 {
     LocationBean temp_location_bean = location_object.getValue();
     if (params[0].matches(temp_location_bean.getZip_code())) {
         master_location = temp_location_bean.getCity() + "," 
             + temp_location_bean.getState()
             + ", (" + temp_location_bean.getZip_code() +")";
     }
 }

It takes over 20 seconds.... Shouldn't the performance be relatively quick? How can I improve the performance here?

tl;dr how can I optimize the reads in this example?

Answer 1

If you're looking for performance then you shouldn't iterate the entrySet to lookup a keyed zipcode. Instead, you might use the HashMap and get the value by its' key. Like,

LocationBean temp_location_bean = this.locations_as_beans_list.get(params[0]);
if (temp_location_bean != null) {
    master_location = temp_location_bean.getCity() + "," 
            + temp_location_bean.getState() 
            + ", (" + temp_location_bean.getZip_code() +")";
}