title: How to change column types in Spark SQL's(In java) DataFrame?
body: <p>I am trying to convert a column data type from long to int in spark sql using java, I have seen some of example in scala and trying out but, Its not wotking</p>
  
  <pre><code>df.withColumn("is_open",  toInt("is_open"));  
  </code></pre>
  
  <p>where do I need to change.
  thanks in advance</p>