Enum with properties and methods in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an enum class named Color.

Kotlin

enum class [1] {
    RED, GREEN, BLUE
}

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

Acolor

BPaint

CColors

DColor

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase names for enum classes.

Using plural form when singular is expected.

The enum class must be named Color exactly as specified.

2fill in blank

medium

Complete the code to add a property 'rgb' to each enum constant.

Kotlin

enum class Color(val [1]: Int) {
    RED(0xFF0000), GREEN(0x00FF00), BLUE(0x0000FF)
}

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Avalue

Brgb

Ccode

DcolorCode

Attempts:

3 left

💡 Hint

Common Mistakes

Using generic names like 'code' or 'value' instead of 'rgb'.

Using camelCase incorrectly.

The property name is rgb to represent the color code.

3fill in blank

hard

Fix the error in the method that returns the color name in lowercase.

Kotlin

enum class Color(val rgb: Int) {
    RED(0xFF0000), GREEN(0x00FF00), BLUE(0x0000FF);

    fun colorName() = name.[1]()
}

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Alowercase

BtoLowerCase

CtoUpperCase

Duppercase

Attempts:

3 left

💡 Hint

Common Mistakes

Using Java method toLowerCase() which is deprecated in Kotlin.

Using uppercase methods instead of lowercase.

In Kotlin, the correct method to convert a string to lowercase is lowercase().

4fill in blank

hard

Fill both blanks to add a method that returns the hex string of the rgb value.

Kotlin

enum class Color(val rgb: Int) {
    RED(0xFF0000), GREEN(0x00FF00), BLUE(0x0000FF);

    fun hex() = "#$[1].format(\"%06X\", [2] )"
}

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AString

Brgb

CInt

Dthis.rgb

Attempts:

3 left

💡 Hint

Common Mistakes

Using Int.format which does not exist.

Using this.rgb instead of just rgb.

The String.format method is used to format the rgb integer as a hex string.

So String.format and rgb are needed.

5fill in blank

hard

Fill all three blanks to create a companion object with a method that finds a Color by its rgb value.

Kotlin

enum class Color(val rgb: Int) {
    RED(0xFF0000), GREEN(0x00FF00), BLUE(0x0000FF);

    companion object {
        fun fromRgb(value: Int): Color? = values().[1] { it.[2] == [3] }
    }
}

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Afind

Brgb

Cvalue

DfirstOrNull

Attempts:

3 left

💡 Hint

Common Mistakes

Using find which is not a Kotlin standard function.

Mixing up parameter names inside the lambda.

The method firstOrNull finds the first enum constant matching the condition or returns null.

The lambda compares it.rgb with the input value.