Autoboxing
Description
Java can wrap a primitive automatically.
Explanation
This happens when an object is required.
Example
Integer score = 92;← Chapter 7 — Input, Wrappers & Lambdas
28. Wrapper Classes & Autoboxing
mixed
Description
Wrapper classes represent primitive values as objects. For example, Integer wraps int and Double wraps double.
Wrappers are needed by generic collections and provide parsing utilities. Java can automatically convert between a primitive and its wrapper in many common situations.
Subtopics
Parsing text
Description
Wrapper methods convert String values.
Explanation
Invalid numeric text throws NumberFormatException.
Example
int score = Integer.parseInt("92");Explanation
Use primitive types for simple calculations unless an object is required. A wrapper variable can be null, so unboxing a null wrapper causes NullPointerException.
Example
public class WrapperDemo {
public static void main(String[] args) {
String scoreText = "92";
Integer score = Integer.parseInt(scoreText);
System.out.println(score + 8);
}
}Key points
- Integer wraps int.
- Autoboxing wraps primitives automatically.
- parseInt converts valid numeric text.