Unary operators in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to increment the variable count by 1 using a unary operator.

Java

int count = 5;
count[1];

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

A-

B++

C+=

D--

Attempts:

3 left

💡 Hint

Common Mistakes

Using '--' which decreases the value.

Using '+=' which is not a unary operator.

Using '-' which subtracts but is not unary increment.

The unary increment operator ++ increases the value of count by 1.

2fill in blank

medium

Complete the code to negate the boolean variable isActive using a unary operator.

Java

boolean isActive = true;
isActive = [1]isActive;

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

A!

B--

C++

D~

Attempts:

3 left

💡 Hint

Common Mistakes

Using '++' or '--' which are for numeric increments or decrements.

Using '~' which is bitwise complement, not for booleans.

The unary logical complement operator ! negates a boolean value.

3fill in blank

hard

Fix the error in the code by choosing the correct unary operator to decrement num by 1.

Java

int num = 10;
num[1];

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

A*

B++

C+

D--

Attempts:

3 left

💡 Hint

Common Mistakes

Using '++' which increases the value.

Using '+' or '*' which are binary operators and cause errors here.

The unary decrement operator -- decreases the value of num by 1.

4fill in blank

hard

Fill both blanks to create a map of numbers to their negations using unary operators.

Java

Map<Integer, Integer> negations = Map.of(1, [1]1, 2, [2]2);

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

A-

B++

C--

D!

Attempts:

3 left

💡 Hint

Common Mistakes

Using '++' or '--' which change the number by one, not negate.

Using '!' which is for booleans, not numbers.

The unary minus operator - negates numbers, turning positive to negative.

5fill in blank

hard

Fill all three blanks to create a map where keys are numbers and values are their incremented, negated, and decremented forms respectively.

Java

int one = 1, two = 2, three = 3;
Map<Integer, Integer> results = Map.of(
  one, [1]one,
  two, [2]two,
  three, [3]three);

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

A++

B-

C--

D!

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!' which is only for booleans.

Mixing prefix and postfix operators incorrectly.

Use ++ to increment, - to negate, and -- to decrement the numbers.