Autoboxing is the process by which a primitive type is automatically encapsulated (boxed) into its equivalent type wrapper whenever an object of that type is needed.
Auto-unboxing is the process by which the value of a boxed object is automatically extracted (unboxed) from a type wrapper when its value is needed.
For example, the following code constructs an Integer object that has the value 100:
public class Main {
public static void main(String[] argv) {
Integer iOb = 100; // autobox an int
}
}
To unbox an object, simply assign that object reference to a primitive-type variable. For example, to unbox iOb, you can use this line:
public class Main {
public static void main(String[] argv) {
Integer iOb = 100; // autobox an int
int i = iOb; // auto-unbox
}
}
Here is a program using autoboxing/unboxing:
public class Main {
public static void main(String args[]) {
Integer iOb = 100; // autobox an int
int i = iOb; // auto-unbox
System.out.println(i + " " + iOb); // displays 100 100
}
}
Output:
100 100