int is one of the 8 raw data types provided by Java. Java provides encapsulation classes for each primitive type, and integer is the wrapper class provided by Java for Int. The default value for int is 0, and the default value for integer is null, that is, integer can differentiate between unassigned and value 0, and int cannot express an unassigned condition, for example, if you want to express the difference between not taking an exam and the test score of 0, you can only use integer. In JSP development, the default for integer is null, so when displayed in a text box with an El expression, the value is a blank string, and the default value of int defaults to 0, so when the El expression is displayed in the text box, the result is 0, so that int does not work as a type of form data for the Web tier.
In Hibernate, if the OID is defined as an integer type, hibernate can determine whether an object is temporary based on whether its value is null or not, and if the OID is defined for the int type, It is also necessary to set its Unsaved-value property to 0 in the HBM mapping file.
In addition, the integer provides multiple integer-related action methods, such as converting a string to an integer, and also defining constants that represent the maximum and minimum values of integers.
Differences between the integer and int types in Java