Java解析Json文件行以返回该行的一部分

Question

I am having some trouble trying to figure out how to parse a line in a json file so that it only returns part of the line as a string. I will illustrate below:

public String GetDistance(String origin, String destination) throws MalformedURLException, IOException {

    //URL url = new URL("https://maps.googleapis.com/maps/api/distancematrix/json?units=imperial&origins" + origin + ",UK+destination=" + destination + ",UK&key=mykey");
    URL url = new URL("https://maps.googleapis.com/maps/api/distancematrix/json?units=imperial&origins=Cornwall,UK&destinations=London,UK&key=mykey");
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("GET");
    String line, outputString = "";
    BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
    while ((line = reader.readLine()) != null) {

        if (line.contains("distance")) {
            outputString = reader.readLine().trim();

            return outputString;
        }

    }

    return outputString;
}

What this function does is create a json file in my browser using Google Maps API:

{
   "destination_addresses" : [ "London, UK" ],
   "origin_addresses" : [ "Cornwall, UK" ],
   "rows" : [
      {
         "elements" : [
            {
               "distance" : {
                  "text" : "284 mi",
                  "value" : 456443
               },
               "duration" : {
                  "text" : "4 hours 52 mins",
                  "value" : 17530
               },
               "status" : "OK"
            }
         ]
      }
   ],
   "status" : "OK"
}

Currently the "outputString" returns the line: "text" : "284 mi". However, the desired output is to just return the miles, "284".

I know this is most likely a re post, however I have been searching around for a solution to this and have been unsuccessful in implementing something that works.

Any help on this would be greatly appreciated, Cheers.

Answer 1

You can have 2 solutions:

1. Parse the JSON and treat it as an object and then just return the String you're looking for.

2. Split the line as follows:

    outputString = reader.readLine().trim(); 

   That line above returns "text" : "284 mi"

   Then you need to split the line by : :

    outputString.split(":") 

   That should create an array with 2 Strings: "text" and "284 mi"

   Then take the second String and split it by a space and take the first String:

    outputString.split("\\\\s") 

   Now you have: "284

   Then just return it from subindex 1 till the end, see docs :

    outputString.substring(1) 

   And then just put it all together:

    return outputString.split(":")[1].split("\\\\s")[0].substring(1) 

I haven't tried above code but it should work.

BTW follow Java Naming Conventions

• firstWordLowerCaseVariable
• firstWordLowerCaseMethod()
• FirstWordUpperCaseClass
• ALL_WORDS_UPPER_CASE_CONSTANT

And use them consistently