Why wrapper classes are used in Java - Test Your Understanding

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Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an Integer wrapper object from a primitive int.

Java

Integer num = [1];

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Aint(5)

B5

CInteger.valueOf(5)

Dnew Integer(5)

Attempts:

3 left

2fill in blank

medium

Complete the code to convert a String to an Integer using wrapper class methods.

Java

Integer num = Integer.[1]("123");

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AparseInt

BvalueOf

CtoString

DintValue

Attempts:

3 left

3fill in blank

hard

Fix the error in the code to correctly convert an Integer to a primitive int.

Java

int value = num.[1]();

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AintValue

BtoInt

CparseInt

DvalueOf

Attempts:

3 left

4fill in blank

hard

Fill both blanks to create a list of Integer objects from an array of ints.

Java

int[] arr = {1, 2, 3};
List<Integer> list = new ArrayList<>();
for (int num : arr) {
    list.[1](Integer.[2](num));
}

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Aadd

BvalueOf

Cappend

DparseInt

Attempts:

3 left

5fill in blank

hard

Fill all three blanks to create a map of String keys to Integer values where values are only added if greater than 10.

Java

Map<String, Integer> map = new HashMap<>();
for (String key : keys) {
    Integer val = Integer.[1](key.length());
    if (val [2] 10) {
        map.[3](key, val);
    }
}

🎯 Drag options to blanks, or click blank then click option

AvalueOf

B>

Cput

Dadd

Attempts:

3 left