IMAD

Understanding Button Interactions

Button Click Functionality

• Button Reference: A variable called button is created to reference the component BTN click me.

• setOnClickListener: This built-in Android Studio function allows you to define actions when the button is clicked.

• Changing Text: When the button is clicked, the action will set the text attribute of the TextView, identified as TXT hello world, to "button clicked".

Code Explanation

• Declaring Button Variable: button refers to BTN click me in the designer, initialized with findViewById.

• Event Trigger: Upon clicking the button, due to setOnClickListener, the TextView text changes as specified.

• Observation: Clicking the button effectively changes the text from "hello world" to "button clicked".

Variable Declarations in Programming

Syntax Overview

• Variable Declaration: Example of variable declaration—val myInt = 25.

• Data Types Covered:

  • Integer: Holds whole numbers (e.g., myInt).

  • Double: Handles decimal values (e.g., myDouble = 3.14).

  • Char: Represents single characters (e.g., myChar = 'a').

  • Boolean: True or false values (e.g., myBoolean = true).

  • String: Sequence of characters (e.g., myString = "Programming is fun").

Proper Use of Data Types

• Restrictions: You cannot assign decimal values to integer variables.

• Character Representation: Strings use double quotes whereas chars use single quotes.

Using Additional Buttons

Introduction of Button Two

• Second Button Reference: A variable called buttonTwo will reference the button BTN display me.

• setOnClickListener: Similar to button, using this will define action upon clicking this new button.

Displaying Multiple Variables

• Code Logic: On clicking buttonTwo, the TextView text should display multiple variables.

• String Interpolation: Uses three double quotes to display formatted text.

Syntax for Displaying Variables

• Structure:

  • Data Type, followed by a colon, then a dollar sign and the variable name (e.g., "int: 25").

  • Each variable's value must be prefixed with its data type and denoted with a colon and a dollar sign for proper conversion.

• Example for Different Data Types:

  • int: $myInt will display the integer stored in myInt (25).

  • double: $myDouble correlates to 3.14 stored in myDouble.

  • char: $myChar for character 'a'.

  • boolean: $myBoolean for true or false status.

  • string: $myString for the string content.

Important Note

• Avoid declaring textView.text repeatedly for each variable; apply it once before compiling all variables to be displayed at once.

• Use formatting to present all values together with proper spacing.