BAEL 1269 Intro to JSON-JAVA (#3493)

* Final commit

* Made changes as per last review

* Moved from core-java to json module

json/src/main/java/com/baeldung/jsonjava/JSONObjectDemo.java

@@ -0,0 +1,59 @@
+package com.baeldung.jsonjava;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.json.JSONObject;
+
+public class JSONObjectDemo {
+    public static void main(String[] args) {
+        System.out.println("4.1. Creating JSONObject: ");
+        jsonFromJSONObject();
+        
+        System.out.println("\n4.2. Creating JSONObject from Map: ");
+        jsonFromMap();
+        
+        System.out.println("\n4.3. Creating JSONObject from JSON string: ");
+        jsonFromJSONString();
+        
+        System.out.println("\n4.4. Creating JSONObject from Java Bean: ");
+        jsonFromDemoBean();
+    }
+    
+    public static void jsonFromJSONObject() {
+        JSONObject jo = new JSONObject();
+        jo.put("name", "jon doe");
+        jo.put("age", "22");
+        jo.put("city", "chicago");
+             
+        System.out.println(jo.toString());
+    }
+    
+    public static void jsonFromMap() {
+        Map<String, String> map = new HashMap<>();
+        map.put("name", "jon doe");
+        map.put("age", "22");
+        map.put("city", "chicago");
+        JSONObject jo = new JSONObject(map);
+         
+        System.out.println(jo.toString());
+    }
+    
+    public static void jsonFromJSONString() {
+        JSONObject jo = new JSONObject(
+          "{\"city\":\"chicago\",\"name\":\"jon doe\",\"age\":\"22\"}"
+        );
+        
+        System.out.println(jo.toString());
+    }
+    
+    public static void jsonFromDemoBean() {
+        DemoBean demo = new DemoBean();
+        demo.setId(1);
+        demo.setName("lorem ipsum");
+        demo.setActive(true);
+         
+        JSONObject jo = new JSONObject(demo);
+        System.out.println(jo);
+    }
+}