Autoboxing is the automatic
conversion that the Java compiler makes between the primitive types and
their corresponding object wrapper classes. If
the conversion goes the other way, this is called unboxing
Autoboxing
Character ch =
'a';
List<Integer>
li = new ArrayList<>();
for (int i = 1; i
< 50; i += 2)
li.add(i); //it creates an Integer object from i and adds the object to li.
******************
List<Integer>
li = new ArrayList<>();
for (int i = 1; i
< 50; i += 2)
li.add(Integer.valueOf(i)); // compiler converts the previous code
to the following at runtime
unboxing
Integer i = new Integer(-8);
// Unboxing
through method invocation
int absVal
= absoluteValue(i);
List<Double> ld = new ArrayList<>();
ld.add(3.1416); // autoboxed through method invocation.
// Unboxing
through assignment
double pi =
ld.get(0);
Primitive type
|
Wrapper class
|
boolean
|
Boolean
|
byte
|
Byte
|
char
|
Character
|
float
|
Float
|
int
|
Integer
|
long
|
Long
|
short
|
Short
|
double
|
Double
|
Benefits
of Autoboxing / Unboxing
- Autoboxing / Unboxing lets us use primitive types and Wrapper class objects interchangeably.
- We don't have to perform explicit typecasting
- It helps prevent errors, but may lead to unexpected results sometimes. Hence must be used with care.
