Day36 of #100DaysOfCode

#CodeTogether Day 36/100

Hii folks 🙌

Today I completed the last few lessons of the same Pathway 4, where I learned to add conditional behavior and image to the app.

Unit 1: Kotlin basics

Pathway 4: Add a button to an app

Source: https://developer.android.com/courses/android-basics-kotlin/course

Add conditional behavior in Kotlin

• We use an if statement to set a condition for executing some instructions. For example, if the user rolls the lucky number, print a winning message.

fun main() {
   val num = 5
   if (num > 4) {
       println("The variable is greater than 4")
   }
}

• The Boolean datatype has values of true and false and can be used for decision-making.
• Compare values using operators such as greater than (>), less than (<), and equal to (==).
• We use a chain of else if statements to set multiple conditions. For example, print a different message for each possible dice roll.
• We use an else statement at the end of a chain of conditions to catch any cases that may not be covered explicitly. If we cover the cases for 6-sided dice, an else statement would catch the 7 and 8 numbers rolled with 8-sided dice.

fun main() {
    val num = 4
    if (num > 4) {
        println("The variable is greater than 4")
    } else if (num == 4) {
        println("The variable is equal to 4")
    } else {
        println("The variable is less than 4")
    }
}

• We use a when statement as a compact form of executing code based on comparing a value.

when (rollResult) {
    luckyNumber -> println("You won!")
    1 -> println("So sorry! You rolled a 1. Try again!")
    2 -> println("Sadly, you rolled a 2. Try again!")
    3 -> println("Unfortunately, you rolled a 3. Try again!")
    4 -> println("No luck! You rolled a 4. Try again!")
    5 -> println("Don't cry! You rolled a 5. Try again!")
    6 -> println("Apologies! you rolled a 6. Try again!")
}

• The general form of if-else:

if (condition-is-true) {
  execute-this-code
} else if (condition-is-true) {
  execute-this-code
} else {
  execute-this-code
}

• When statement:

when (variable) {
  matches-value -> execute-this-code
  matches-value -> execute-this-code
}

Add images to the Dice Roller app

• We usesetImageResource()to change the image that's displayed in an ImageView

private fun rollDice() {
    val dice = Dice(6)
    val diceRoll = dice.roll()
    val diceImage: ImageView = findViewById(R.id.imageView)
    diceImage.setImageResource(R.drawable.dice_2)
}

• We use control flow statements like if / else expressions or when expressions to handle different cases in our app, for example, showing different images under different circumstances.

/**
* Roll the dice and update the screen with the result.
*/
private fun rollDice() {
    // Create new Dice object with 6 sides and roll the dice
    val dice = Dice(6)
    val diceRoll = dice.roll()
    // Find the ImageView in the layout
    val diceImage: ImageView = findViewById(R.id.imageView)
    // Determine which drawable resource ID to use based on the dice roll
    val drawableResource = when (diceRoll) {
        1 -> R.drawable.dice_1
        2 -> R.drawable.dice_2
        3 -> R.drawable.dice_3
        4 -> R.drawable.dice_4
        5 -> R.drawable.dice_5
        else -> R.drawable.dice_6
    }
    // Update the ImageView with the correct drawable resource ID
    diceImage.setImageResource(drawableResource)
    // Update the content description
    diceImage.contentDescription = diceRoll.toString()
}

That is all for Day36 ✅

Thanks for reading, See you tomorrow!