Using Objects in AP Computer Science A

Autoboxing and unboxing

ONLY WITHIN CONDITIONAL STATEMENTS THAT REQUIRE OBJECTS.

WHEN WE CALL THE VALUEOF AND PARSE METHODS ON WRAPPER CLASSES.

DURING COMPILATION TIME TO OPTIMIZE CODE EFFICIENCY.

They provide additional static utility methods.

They convert primitives into objects.

They ensure type safety through generics.

They handle automatic conversion between strings and primitives.

Double.toString(42.d)

Interger.parseInt("three")

Interger.toString(3)

String.valueOf(true)

Increase security by preventing direct access to machine level data representation.

They can then be used with generic data structures like Collections that only accept objects.

It reduces memory usage by optimizing storage space for simple data types.

It enhances performance by lowering overhead associated with autoboxing operations.

Summing up numeric values using Number's intValue() method for Integers and doubleValue() method for Doubles, respectively, while handling potential overflow or precision loss scenarios correctly based on context requirements.

Calling doubleValue() on each Number object before addition ensuring decimal precision is maintained across types.

Checking instanceof for each element before deciding how to cast them prior to summation.

Casting each element to Integer before addition regardless of actual type.

The result will be true since .equals() checks for equality in values and both represent the same numerical value.

The result will be false because they are two different objects in memory.

The result is undefined as precision differences affect wrapper class comparisons.

An error occurs since wrapper classes cannot use .equals() to compare values.

"123"

123

A NumberFormatException

null

Dividing one Integer by another involves unboxing before performing arithmetic operations.

Comparing two int primitives with '==' does not involve any wrapper classes.

Assigning an int primitive to an Integer object variable performs boxing automatically.

Assigning an Integer object to another Integer object simply copies references without boxing.

Explicitly managing object creation and reuse by maintaining your own cache of frequently used Integer instances.

Using Integer objects in place of int wherever possible in your code.

Minimizing calls to methods that require conversion between primitive types and wrapper classes.

Utilizing primitive data types like int instead of wrapper classes like Integer when possible.

Integer x = Integer.valueOf(5);

Integer x = 5;

Integer x = Integer.parseInt("5");

Integer x = new Integer(5);