Autoboxing in Java - Interactive Code Practice

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Practice - 5 Tasks

1fill in blank

easy

Complete the code to autobox the int value into an Integer object.

Java

int num = 10;
Integer boxedNum = [1];

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Aint

Bnew Integer(num)

CInteger.valueOf(num)

Dnum

Attempts:

3 left

2fill in blank

medium

Complete the code to unbox the Integer object to a primitive int.

Java

Integer boxedNum = 20;
int num = [1];

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AInteger.parseInt(boxedNum)

BboxedNum

C(int) boxedNum

DboxedNum.intValue()

Attempts:

3 left

3fill in blank

hard

Fix the error in autoboxing when adding a primitive int to a List of Integer.

Java

List<Integer> list = new ArrayList<>();
int num = 5;
list.add([1]);

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Anum

Bnew Integer(num)

CInteger.valueOf(num)

D"num"

Attempts:

3 left

4fill in blank

hard

Fill both blanks to create a Map with Integer keys and values using autoboxing.

Java

Map<Integer, Integer> map = new HashMap<>();
int key = 1;
int value = 100;
map.put([1], [2]);

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Akey

Bvalue

C"key"

D"value"

Attempts:

3 left

5fill in blank

hard

Fill all three blanks to create a List of Integer squares using autoboxing and a for loop.

Java

List<Integer> squares = new ArrayList<>();
for (int i = 1; i <= 5; i++) {
    squares.add(i [1] [2]);
}
int firstSquare = squares.get([3]);

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A*

Bi

C0

D+

Attempts:

3 left