title: Get json key name from json.javax.JsonObject?
body: <p>Suppose I have a JsonObject from <a href="http://docs.oracle.com/javaee/7/api/javax/json/JsonObject.html" rel="nofollow">javax</a> named jsonObject, which looks like this: <code>{"key":"value"}</code></p>
  
  <p>How can I get the key name <code>key</code>?</p>
  
  <p>I only find methods like <code>getJsonString</code> to get the key value <code>value</code>, but not the name of the key itself.</p>
  
  <p>Background:</p>
  
  <p>I have a Json Array, which contains key-value pairs. I want to know the name of the key on a specific index <code>i</code>.</p>
  
  <p>Example:</p>
  
  <p><code>[{"key1":"value0"},{"key1":"value1"},{"key2","value2"}]</code></p>
  
  <p><code>key1</code> here is a success, <code>key2</code> is a fail and has to be checked.</p>