Wrapper Class in Java

Java platform  provides primitive data types has a class dedicated to it. These are known as wrapper classes, because they "wrap" the primitive data type into an object of that class. Often, the wrapping is done by the compiler-if you use a primitive where an object is expected, the compiler boxes the primitive in its wrapper class for you. Similarly, if you use a number object when a primitive is expected, the compiler unboxes the object for you.So, there is anInteger class that holds an int variable, there is a Double class that holds a double variable, and so on.


Example for primitive data types and classes



Primitive type           Wrapper class Constructor Arguments

    byte                          Byte                       byte or String

    short                         Short                      short or String
    int                             Integer                    int or String
    long                          Long                      long or String
    float                          Float                      float, double or String

    double                      Double                   double or String

    char                         Character               char
    boolean                    Boolean                 boolean or String