How can we read a JSON file in Java?

The JSON is one of the widely used data-interchange formats and is a lightweight and language independent. The json.simple is a lightweight JSON processing library that can be used to read and write JSON files and it can be used to encode or decode JSON text and fully compliant with JSON specification (RFC4627). In order to read a JSON file, we need to download the json-simple.jar file and set the path to execute it.

json file

Example

<span class="kwd">import</span><span class="pln"> java</span><span class="pun">.</span><span class="pln">io</span><span class="pun">.*;</span><span class="pln">
</span><span class="kwd">import</span><span class="pln"> java</span><span class="pun">.</span><span class="pln">util</span><span class="pun">.*;</span><span class="pln">
</span><span class="kwd">import</span><span class="pln"> org</span><span class="pun">.</span><span class="pln">json</span><span class="pun">.</span><span class="pln">simple</span><span class="pun">.*;</span><span class="pln">
</span><span class="kwd">import</span><span class="pln"> org</span><span class="pun">.</span><span class="pln">json</span><span class="pun">.</span><span class="pln">simple</span><span class="pun">.</span><span class="pln">parser</span><span class="pun">.*;</span><span class="pln">
</span><span class="kwd">public</span><span class="pln"> </span><span class="kwd">class</span><span class="pln"> </span><span class="typ">JSONReadFromTheFileTest</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
   </span><span class="kwd">public</span><span class="pln"> </span><span class="kwd">static</span><span class="pln"> </span><span class="kwd">void</span><span class="pln"> main</span><span class="pun">(</span><span class="typ">String</span><span class="pun">[]</span><span class="pln"> args</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
      </span><span class="typ">JSONParser</span><span class="pln"> parser </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">JSONParser</span><span class="pun">();</span><span class="pln">
      </span><span class="kwd">try</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
         </span><span class="typ">Object</span><span class="pln"> obj </span><span class="pun">=</span><span class="pln"> parser</span><span class="pun">.</span><span class="pln">parse</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">FileReader</span><span class="pun">(</span><span class="str">"/Users/User/Desktop/course.json"</span><span class="pun">));</span><span class="pln">
         </span><span class="typ">JSONObject</span><strong><span class="pln"> </span></strong><span class="pln">jsonObject </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="typ">JSONObject</span><span class="pun">)</span><span class="pln">obj</span><span class="pun">;</span><span class="pln">
         </span><span class="typ">String</span><span class="pln"> name </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="typ">String</span><span class="pun">)</span><span class="pln">jsonObject</span><span class="pun">.</span><span class="kwd">get</span><span class="pun">(</span><span class="str">"Name"</span><span class="pun">);</span><span class="pln">
         </span><span class="typ">String</span><span class="pln"> course </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="typ">String</span><span class="pun">)</span><span class="pln">jsonObject</span><span class="pun">.</span><span class="kwd">get</span><span class="pun">(</span><span class="str">"Course"</span><span class="pun">);</span><span class="pln">
         </span><span class="typ">JSONArray</span><span class="pln"> subjects </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="typ">JSONArray</span><span class="pun">)</span><span class="pln">jsonObject</span><span class="pun">.</span><span class="kwd">get</span><span class="pun">(</span><span class="str">"Subjects"</span><span class="pun">);</span><span class="pln">
         </span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Name: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> name</span><span class="pun">);</span><span class="pln">
         </span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Course: "</span><span class="pln"> </span><span class="pun">+</span><span class="pln"> course</span><span class="pun">);</span><span class="pln">
         </span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Subjects:"</span><span class="pun">);</span><span class="pln">
         </span><span class="typ">Iterator</span><span class="pln"> iterator </span><span class="pun">=</span><span class="pln"> subjects</span><span class="pun">.</span><span class="pln">iterator</span><span class="pun">();</span><span class="pln">
         </span><span class="kwd">while</span><span class="pln"> </span><span class="pun">(</span><span class="pln">iterator</span><span class="pun">.</span><span class="pln">hasNext</span><span class="pun">())</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
            </span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="pln">iterator</span><span class="pun">.</span><span class="kwd">next</span><span class="pun">());</span><span class="pln">
         </span><span class="pun">}</span><span class="pln">
      </span><span class="pun">}</span><span class="pln"> </span><span class="kwd">catch</span><span class="pun">(</span><span class="typ">Exception</span><span class="pln"> e</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
         e</span><span class="pun">.</span><span class="pln">printStackTrace</span><span class="pun">();</span><span class="pln">
      </span><span class="pun">}</span><span class="pln">
   </span><span class="pun">}</span><span class="pln">
</span><span class="pun">}</span>

Output

Name: Raja
Course: MCA
Subjects:
subject1: MIS
subject2: DBMS
subject3: UML