The wrapper's main purpose is to provide a 'different' way to use wrapped object (perhaps the wrapper provides a simpler interface, or adds some functionality). The word 'wrapper' can also be used when describing classic design patterns. Wrapping an object to provide a simplified interface to it is often described as the 'Facade' pattern.
Where and how is the term used "wrapper" used in programming, and what ...
A wrapper class (as adapter) is used when the wrapper must respect a particular interface and must support a polymorphic behavior. On the other hand, a facade is used when one wants an easier or simpler interface to work with.
When I should go for wrapper class over primitive types? Or On what circumstance I should choose between wrapper / Primitive types?
A wrapper class wraps (encloses) around a data type (can be any primitive data type such as int, char, byte, long) and makes it an object. Here are a few reasons why wrapper classes are needed: Allows null values. Can be used in collection such as List, Map, etc. Can be used in methods which accepts arguments of Object type.
Wrapper Class: Java uses primitive types, such as int, char, double to hold the basic data types supported by the language. Sometimes it is required to create an object representation of these primitive types. These are collection classes that deal only with such objects. One needs to wrap the primitive type in a class. To satisfy this need, java provides classes that correspond to each of the ...
a "wrapper" is just a term for some element that encapsulates all other visual elements on the page. The body tag seems to fit the bill, but you would be at the mercy of the browser to determine what displays beneath that if you adjust the max-width.