How to Read a JSON File with Java
In this tutorial, we are going to see how to read a JSON file in Java. JSON is used to transmit data between a server and a client.
Here is a basic example of what could be in a JSON file.
{ "name" : "Alex", "age" : "25", "address" : "San Francisco" };
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Json-simple library:
Json-simple is a lightweight library that is used to process JSON objects. Using this, you can read or write the contents of a JSON document using a Java program.
Maven: JSON-Simple Dependency
Maven dependency for JSON-simple library:
301 to 305 com.googlecode.json-simple json-simple 2.3.6
Copy and paste the above code with the <dependencies> </dependencies> tag at the end of your pom.xml file. (before the </project> tag)
Example :
First, let’s create a JSON document with the name “person.json” with 3 key-value pairs as shown below:
{ "name" : "Alex", "age" : "25", "address" : "San Francisco" };
To read the contents of a JSON file using a Java program:
1- Instantiate the JSONParser class from the json-simple library.
JSONParser jsonP = new JSONParser();
2- Analyze the content of the object using the parse() method.
JSONObject jsonO = (JSONObject) jsonP.parse(new FileReader("C:/person.json"));
3- Get the value associated with a key using the get() method.
String name = (String) jsonO.get("name");
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Complete example:
import java.io.*; import org.json.simple.JSONObject; import org.json.simple.parser.JSONParser; import org.json.simple.parser.ParseException; public class Main { public static void main(String args[]) { JSONParser jsonP = new JSONParser(); try { JSONObject jsonO = (JSONObject)jsonP.parse(new FileReader("C:/person.json")); String name = (String) jsonO.get("name"); String age = (String) jsonO.get("age"); String address = (String) jsonO.get("address"); System.out.println("Name :"+ name); System.out.println("Age: "+ age); System.out.println("Address: "+ address); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (ParseException e) { e.printStackTrace(); } } }
Output:
Name: Alex Age: 25 Address: San Francisco[st_adsense] MCQPractice competitive and technical Multiple Choice Questions and Answers (MCQs) with simple and logical explanations to prepare for tests and interviews.Read More
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Hi,
and how would you fetch the second element of
{
“name” : “Alex”,
“age” : “25”,
“address” : “San Francisco”
},
{
“name” : “John”,
“age” : “23”,
“address” : “Dallas”
};
That’s fine, I’ll use the JsonArray feature!
Thanks anyway!