go to previous page   go to home page   go to next page hear noise

Answer:

Yes. Sometimes your data is an int, a primitive, but you need the data in an object.

For example, a method might require an object for a parameter, but what you have is an int.


Type Wrappers

There is a division between primitive data and objects. The division sometimes needs to be crossed. For each primitive type, there is a corresponding wrapper class. A wrapper class is used to put primitive data value into an object. Think of wrapping up the data with an object, like wrapping up a gift.

Wrapper classes can also go the other direction. Objects (of a wrapper class) can be converted into primitive data. The table shows primitive types and their wrapper classes. Java is case sensitive, so byte and Byte are different types.

As an example, the value 103 could be held in 32 bit section of memory that is of primitive data type int. The same value could be held in an object that is of type Integer. The object will use many more than 32 bits.

The wrapper classes are defined in the package java.lang and so (like all classes in that package) are automatically available to your programs.

primitive typeWrapper type
byte Byte
short Short
int Integer
long Long
float Float
double Double
char Character
boolean Boolean

QUESTION 19:

Is String a wrapper class?