Type Wrappers - 12,17

Question 1

What are type wrappers?

Answer 1

Primitive types like int, double sometimes need object representation to get more functionality.

Can wrap the type in a class/object to get more. e.g.
Double, Integer, Character.

Question 2

what is boxing and unboxing?

Answer 2

process of encapsulating a value within an object and visa versa. From primitive types to wrapper objects.

Integer iob = Integer.valueOf(100)

Question 3

make a double thats the numeric value of string “3214”

Answer 3

Double d1 = Double.valueOf(“3214”)

Question 4

Covert string to number.

Answer 4

String str;
int i;

str = “120”
i = Integer.parseInt(str)

Question 5

explain method in Integer:

static int parseInt (String s)

Answer 5

Converts the string s and returns its integer value

Question 6

explain method in Integer

int intValue()

Answer 6

returns the value of an Integer object as an int type

Question 7

Explain constructor methods in Integer:

Integer (int n)
Integer (String s)

Answer 7

constructs and Integer object form an int type or String type

Question 8

Integer methods list

Answer 8

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