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Parsing JSON in Java

My experience with Java is pretty limited. I took a Java course some ten years ago and professionally I have only been involved in one larger Java project. Therefore I thought it was time for a mini-project in Java.

I prefer JSON over XML any day. Therefore I thought that a good mini-project would be to investigate the possibility to parse JSON using Java. After a few Google searches I decided to give Google's Java library GSON a try.

GSON can be used to create JSON representations of Java objects and to create Java objects from JSON strings. I focused on the latter of these two.
If you use Eclipse it is really easy to add the GSON library to your Java project. Just download the jar and store it at a good location. Then in Eclipse, select the properties for your project and under "Java Build Path" -> "Libraries" press "Add External Jars..." and select the downloaded jar file.

Here follows a simple test case using JUnit:

1:  package se.thecodedworld.junit;  
2:  import se.thecodedworld.ParsingJson;  
3:  import static org.junit.Assert.*;  
4:  import org.junit.Before;  
5:  import org.junit.Test;  
6:  public class JunitParserTest {  
7:       private ParsingJson parser;  
8:       @Before  
9:       public void setUp()  
10:       {  
11:            parser = new ParsingJson();  
12:       }  
13:       @Test  
14:       public void basicParse()  
15:       {  
16:            String basicJsonString = "{ \"name\": \"Eric\", \"age\": 36}";  
17:            parser.parse(basicJsonString);  
18:            assertEquals("Eric", parser.getValue("name"));  
19:            assertEquals("36", parser.getValue("age"));  
20:       }  
21:  }

And the implemetation:

1:  package se.thecodedworld;  
2:  import com.google.gson.JsonObject;  
3:  import com.google.gson.JsonParser;  
4:  public class ParsingJson {  
5:       private JsonObject jsonObject;  
6:       public void parse(String jsonString)  
7:       {  
8:            jsonObject = new JsonParser().parse(jsonString).getAsJsonObject();  
9:       }  
10:       public String getValue(String key)  
11:       {  
12:            return jsonObject.get(key).getAsString();  
13:       }  
14:  }

Next I will attempt to create a class, convert it to a JSON string and then convert it back to an object. That will be the mini-project for tomorrow.

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