Menu
Jpa entity generator assigns Integer type to the id fields of my entities. The corresponding attribute/column in my DB is of type serial ( yep postgres). I would also assign the integer type to my entities id fields. But i have seen usage of Long getId() on this page. I have also seen this type of type assigning on the geomajas examples. Is there any gotcha when it comes to using Integer? I mean, yeah you have to be careful with integer that the id is not below 0 but at the same time you also have to make sure that your Long Id is not bigger than 2,147,483,647. So what's deal here?
EDIT: I was making a confusion between Long and unsigned integer so i guess what i was thinking was "unsigned integer versus Integer for the id field of java entities" which is nonsense now that my confusion between long and unsigned integer is gone. My bad. Thank you for your answers and comments. I guess if i would have used bigserial jpa entity generator would have used Long too.
503
Identifiers in Java Here are the rules: All identifiers must start with either a letter( a to z or A to Z ) or currency character($) or an underscore. After the first character, an identifier can have any combination of characters. A Java keyword cannot be used as an identifier.
An entity is a lightweight persistence domain object. Typically, an entity represents a table in a relational database, and each entity instance corresponds to a row in that table. The primary programming artifact of an entity is the entity class, although entities can use helper classes.
Entities in JPA are nothing but POJOs representing data that can be persisted to the database. An entity represents a table stored in a database. Every instance of an entity represents a row in the table.
The @Entity annotation specifies that the class is an entity and is mapped to a database table. The @Table annotation specifies the name of the database table to be used for mapping.
Long has a much bigger capacity than Integer data type, so if you are not sure what length your data is going to be, its better to be using Long type data...
On the other hand, since Long has a bigger capacity it uses extra space and if you are sure that your data will not be bigger than the Integer data type then using Long just makes your code inefficient
75
Jpa entity generator assigns Integer type to the id fields of my entities
You set the type of the id field, the JPA generator fills it with unique values. You are free to use Integer or Long.
Is there any gotcha when it comes to using Integer?
Not really, the only difference between Integer & Long is the number of bits (64 v 32) and permissable range:
Integer: -2,147,483,648 to 2,147,483,647
Long: -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
The generator will assign values to the Id field. You can control the initial generated value: for @SequenceGenerator and @TableGenerator, set the initialValue attribute; for Identity generator, modify database DDL definition for the Identity column.
Simply determine (maximum number of Ids generated per week by your app) x (maximum number of weeks your app can be "live"). If the result is less than, say, 1,500,000,000 (giving a safety margin), feel free to use Integer; otherwise use Long.
32
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
