A Wrapper class is a class whose object wraps or contains a primitive data types. When we create an object to a wrapper class, it contains a field and in this field, we can store a primitive data types. In other words, we can wrap a primitive value into a wrapper class object.
Need of Wrapper Classes
- They convert primitive data types into objects. Objects are needed if we wish to modify the arguments passed into a method (because primitive types are passed by value).
- The classes in java.util package handles only objects and hence wrapper classes help in this case also.
- Data structures in the Collection framework, such as ArrayList and Vector, store only objects (reference types) and not primitive types.
- An object is needed to support synchronization in multithreading.
Primitive Data types and their Corresponding Wrapper class
Autoboxing and Unboxing
Autoboxing: Automatic conversion of primitive types to the object of their corresponding wrapper classes is known as autoboxing. For example – conversion of int to Integer, long to Long, double to Double etc.
Unboxing: It is just the reverse process of autoboxing. Automatically converting an object of a wrapper class to its corresponding primitive type is known as unboxing. For example – conversion of Integer to int, Long to long, Double to double etc.
Values of Wrapper objects (printing as objects) Byte object byteobj: 1 Integer object intobj: 10 Float object floatobj: 18.6 Double object doubleobj: 250.5 Character object charobj: a Unwrapped values (printing as data types) byte value, bv: 1 int value, iv: 10 float value, fv: 18.6 double value, dv: 250.5 char value, cv: a
Related Article :
Comparison of Autoboxed Integer objects in Java
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