Topic 2.5: Working With Java Data Types - Develop code that uses wrapper classes such as Boolean, Double, and Integer Flashcards
What is the purpose of the
valueOf() method
in wrapper classes?
This method is a static method available in all wrapper classes. It is used to create an instance of the wrapper class from a specified value.
It can create an object by accepting a value of the corresponding primitive type or by parsing a provided string representation.
These include:
- Boolean
- Byte
- Short
- Integer
- Long
- Float
- Double
- and Character.
Name the
wrapper classes for common primitive types.
What method is available in all wrapper classes to retrieve the primitive value wrapped by the object?
The {primitive}Value() method (e.g., booleanValue(), byteValue(), doubleValue()) is available in all wrapper classes.
It allows you to obtain the corresponding primitive value from the wrapper object.
What is
autoboxing?
This is the automatic conversion of primitive types to their corresponding wrapper class objects.
These features are handled by the Java compiler, making it convenient to work with wrapper classes.
How are autoboxing and unboxing handled in Java?
In which situations can autoboxing and unboxing occur?
These features can occur during:
- assignment and initialization
- during method calls
- and while working with collections.
This is the automatic conversion of wrapper class objects back to their corresponding primitive types.
What is
unboxing?
How are autoboxing and unboxing handled in Java?
These features are handled by the Java compiler, making it convenient to work with wrapper classes.
These are classes in Java that wrap primitive data types, allowing them to be treated as objects and providing additional functionality.
What are
wrapper classes?
What are some examples of properties specific to wrapper classes?
Wrapper classes have constants and properties specific to their data types, such as MAX_VALUE, MIN_VALUE, and SIZE.
These properties provide information about the maximum and minimum values representable by the wrapper class and the size of the data type in bits, respectively.
Name the
wrapper classes for common primitive types.
These include:
- Boolean
- Byte
- Short
- Integer
- Long
- Float
- Double
- and Character.
These features can occur during:
- assignment and initialization
- during method calls
- and while working with collections.
In which situations can autoboxing and unboxing occur?
This is the automatic conversion of primitive types to their corresponding wrapper class objects.
What is
autoboxing?
Is there an exception to the naming convention of wrapper classes?
Yes, the wrapper classes Integer and Character have names that differ from their associated primitive types.
Why is using the valueOf() method generally preferred over the constructor approach?
Using the valueOf() method is generally preferred because it allows for better memory utilization through caching mechanisms. The valueOf() method can reuse objects for commonly used values within a certain range, resulting in improved performance and reduced memory footprint.
Example:Integer.valueOf(1) will always return the same object instance, while new Integer(1) will always create a new one
