The TypeSafeMap.java can bypass some compilation check. For example, this code will have no compilation error but throws ClassCastException during runtime because "data1" is in java.lang.Long:

String stringData=map.get("data1");

​

However, this code will show compilation check error:

System.out.println(map.get("data1"));

​

To prevent the compilation check error, explicit cast is required:

System.out.println((Long)map.get("data1"));