Here, I would like to share an example of very basic JSON parsing with Apex programming language in Salesforce.

MainWrapper Class:

public class MainWrapper {
public Integer studentId;
public String studentName;
public String address;

public MainWrapper(Integer studentId, String studentName, String address) {
this.studentId = studentId;
this.studentName = studentName;
this.address = address;

And now the test class to check whether JSON Parsing is working fine or not.

private class TestMainWrapper {

static testMethod void testJsonParser() {
String jsonMessage = '{"studentId" : 1, "studentName" : "Sudipta Deb", "address" : "Kolkata, India"}';

JSONParser parser = JSON.createParser(jsonMessage);
MainWrapper m = (MainWrapper)parser.readValueAs(MainWrapper.class);

System.assertEquals(1, m.studentId);
System.assertEquals('Sudipta Deb', m.studentName);
System.assertEquals('Kolkata, India', m.address);

I will share more complex JSON Parsing very soon. Any feedback is always welcome.