title: DynamoDBMapper - Failed to instantiate class
body: <p>I'm running into an issue of the Java based DynamoDBMapper in Amazon's AWS toolkit throwing the "Failed to instantiate class" exception error.  This is my first time attempting to use the DBMapper, so I'm not entirely sure I have everything setup right.  My code can be found below:</p>
  
  <pre><code>public static void main(String[] args) {
      dynamoDB = new AmazonDynamoDBClient(credentials);
  
      DynamoDBMapper mapper = new DynamoDBMapper(dynamoDB);
      PStatus data = mapper.load(PStatus.class, "online", new Integer(1655));
      String assigned = data.getAssigned();
      System.out.println(assigned);
  }
  
  @DynamoDBTable(tableName = "projectStatus")
  public class PStatus {
  
      private Integer projID;
      private String status;
      private String assigned;
  
      @DynamoDBHashKey(attributeName = "status")
      public String getStatus() { return status; }
      public void setStatus(String status) { this.status = status; }
  
      @DynamoDBRangeKey(attributeName = "projID")
      public Integer getId() { return projID; }
      public void setId(Integer projID) { this.projID = projID; }
  
      @DynamoDBAttribute(attributeName = "assigned")
      public String getAssigned() { return assigned; }
      public void setAssigned(String assigned) { this.assigned = assigned; }
  }
  </code></pre>
  
  <p>I'm basically just trying to perform a GetItemRequest and then draw out a specific attribute, but I'm getting the error pointing to the line <code>PStatus data = mapper.load(PStatus.class, "onFarm", new Integer(1655));</code>.  What exactly am I doing wrong?</p>
  
  <p>Edit: Exact Exception below:</p>
  
  <pre><code>Exception in thread "main" com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingException: Failed to instantiate class
      at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.createKeyObject(DynamoDBMapper.java:325)
      at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.load(DynamoDBMapper.java:313)
      at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.load(DynamoDBMapper.java:212)
      at test.TestGet.main(TestGet.java:20)
  Caused by: java.lang.InstantiationException: test.TestGet$PStatus
      at java.lang.Class.newInstance0(Unknown Source)
      at java.lang.Class.newInstance(Unknown Source)
      at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.createKeyObject(DynamoDBMapper.java:323)
  </code></pre>