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Is it a best practice to always use long type for database table id columns in Java entity class?

First of all we should understand, java entity class is just a data holder for a row, if the id column of a table is bigint or unsigned int , we should go for long data type for id property in entity class. The reason is very simple, int in java is signed 32 bit value, bigint/int database column type can hold more than 31 bit (eg: mysql) value. If the id column of a database table is int (signed 32 bit) type, using int type for id property in entity class is enough. However if you think the database table id column type will change from int to higher size such as bigint or unsigned int, it may be better to use long for id property in entity class to avoid future code refactoring. There are cases where id type of a database table column will be just int type which will never be changed in future, eg: id type of gender, country, state etc.. tables. So it is not a best practice to blindly declare long type for id property in java entity class.