I have a method which is simply storing flag value true for a particular record. My flag attribute has been defined as Boolean which has value true/false in my DynamoDB database
That's expected, have a look at the datatypes docs for dynamodb: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBMapper.DataTypes.html
The Java type of Boolean will be stored as a number type in dynamodb, 0 or 1.
Alternatively, you can use @DynamoDBNativeBooleanType
to map a Java Boolean
to the DynamoDB BOOL
data type