title: How to remove duplicates elements from JSON file using java if else?
body: <p>This <strong>start</strong> that is found in my codes are from my JSON file. Now that in my JSON file, i have a lot of "start" with the same name. For example in this JSON file, i have duplicates in the start (having both the content as "audi"):</p>
  
  <pre><code>{"rel": "AtLocation", "weight": 0.5, "dataset": "/d/dbpedia/en", "sources": ["/s/dbpedia/3.7"], "id": "0209765bf7185615ef242513f61ca0f61efe2a04", "features": ["audi AtLocation -", "audi - curitiba", "- AtLocation curitiba"], "end": "curitiba", "license": "/l/CC/By-SA", "uri": "/a/[AtLocation/,audi/,curitiba/]", "start": "audi", "context": "/ctx/all", "surfaceText": null}
  
  {"rel": "AtLocation", "weight": 0.5, "dataset": "/d/dbpedia/en", "sources": ["/s/dbpedia/3.7"], "id": "5158d1cfce728efb3e42840d166ec06153a3d77d", "features": ["audi AtLocation -", "audi - ingolstadt", "- AtLocation ingolstadt"], "end": "unite_state", "license": "/l/CC/By-SA", "uri": "/a/[AtLocation/,audi/,ingolstadt/]", "start": "audi", "context": "/ctx/all", "surfaceText": null}
  </code></pre>
  
  <p>This is my Java codes:  </p>
  
  <pre><code>String start = (String) jsonObject.get("start");  
  StartVertex startV = new StartVertex(start);  
  helloGraphDB.addVertex(startV);    
  </code></pre>
  
  <p>I doesnt want it to addVertex 2 times of the same "audi", how do i write the logic if else out?</p>
  
  <p>Thank you.</p>