title: How to troubleshoot java.lang.NumberFormatException: null
body: <p>I am loading a file that has ~500,000 records such as this</p>
  
  <pre><code>ROW_ID, COLOR_CODE, SHADE_ID
  21, 22, 321
  23, 31, 321
  </code></pre>
  
  <p>I load it like this:</p>
  
  <pre><code> val colorSchema = StructType(Array(
           StructField("ROW_ID", IntegerType, true),
           StructField("COLOR_CODE", IntegerType, true),
           StructField("SHADE_ID", IntegerType, true)
  
       def makeSchema(filename:String, tableName:String,
           tableSchema:StructType,uri:String){
  
           val table = spark.read.
             format("com.databricks.spark.csv").
             option("header", "true").
             schema(tableSchema).load(uri+filename).cache()
           table.registerTempTable(tableName.toUpperCase)
         }
  
  makeSchema("colors.csv","colors",colorSchema,"s3://bucket/")
  </code></pre>
  
  <p>The above code runs fine. However, when I run the following query I get an error <code>java.lang.NumberFormatException: null</code></p>
  
  <pre><code>val r = spark.sql("select * from colors where COLOR_CODE = 22").take(1)
  </code></pre>
  
  <p>What am I doing wrong? And how can I spot this issue in an effective way? I have visually scanned the file to see if <code>COLOR_CODE</code> has missing values but I can't see any visually...</p>
  
  <p><strong>Update</strong></p>
  
  <p>I've asked a separate question that narrows down the problem further. The CSV now only has 1 row and I still get the same error. <a href="https://stackoverflow.com/questions/40564201/how-to-resolve-java-lang-numberformatexception-null-in-spark-sql">https://stackoverflow.com/questions/40564201/how-to-resolve-java-lang-numberformatexception-null-in-spark-sql</a></p>