Kotlin Android Toast

Introduction

In Android development, Toast messages are a simple yet effective way to provide brief notifications to users. They appear on the screen for a short duration and do not interrupt the user's interaction with the app. You might have seen Toast messages when a message is sent successfully, or when an operation is completed. Understanding how to use Toasts is essential for creating a user-friendly interface.

Why Use Toasts?

Toasts are useful because they:

• ✅ Provide feedback: They inform users about the status of actions without disrupting their flow.
• ✅ Are non-intrusive: Unlike dialogs, they do not require user interaction to dismiss.
• ✅ Are customizable: You can change their appearance, duration, and position on the screen.

Concept Explanation

Think of a Toast as a sticky note on your computer screen. It conveys a quick message, like "Task completed," and then disappears after a few seconds. This analogy helps illustrate how Toasts deliver brief feedback without requiring the user to take any action.

In comparison to other messaging systems in Android, such as Snackbar, Toasts are less complex and straightforward. While Snackbar can provide more functionality (like action buttons), Toasts are simpler and focus solely on displaying messages.

Syntax Section

To create a Toast message in Kotlin, you generally use the following syntax:

Toast.makeText(context, message, duration).show()

Breakdown of the Syntax

• ✅ Toast.makeText: This is a static method that creates a Toast instance.
• ✅ context: This is the context in which the Toast will be displayed. You usually use applicationContext or this if you're in an activity.
• ✅ message: A String representing the text you want to display.
• ✅ duration: This specifies how long the Toast will be visible. You can use Toast.LENGTHSHORT or Toast.LENGTHLONG.
• ✅ show: This method is called to display the Toast on the screen.

Working Examples

Let’s dive into some complete, runnable examples that illustrate how to use Toast messages in an Android application.

Example 1: Basic Toast Message

fun main() {
    // Basic Toast example
    Toast.makeText(applicationContext, "Welcome to the App!", Toast.LENGTH_SHORT).show()
}

Output:

Welcome to the App!

Example 2: Multiple Toast Messages on Button Click

package com.example.toastdemo

import android.os.Bundle
import android.widget.Button
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val toastButton = findViewById<Button>(R.id.toastButton)
        toastButton.setOnClickListener {
            Toast.makeText(applicationContext, "Toast 1 displayed", Toast.LENGTH_SHORT).show()
            Toast.makeText(applicationContext, "Toast 2 displayed", Toast.LENGTH_SHORT).show()
        }
    }
}

Expected Output:

Toast 1 displayed
Toast 2 displayed

Example 3: Customizing Toast Position

package com.example.toastdemo

import android.os.Bundle
import android.view.Gravity
import android.widget.Button
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val toastButton = findViewById<Button>(R.id.toastButton)
        toastButton.setOnClickListener {
            val myToast = Toast.makeText(applicationContext, "Custom Position Toast", Toast.LENGTH_SHORT)
            myToast.setGravity(Gravity.TOP or Gravity.CENTER_HORIZONTAL, 0, 100)
            myToast.show()
        }
    }
}

Expected Output:

Custom Position Toast (appears at the top center of the screen)

Example 4: Toast with a Long Duration

package com.example.toastdemo

import android.os.Bundle
import android.widget.Button
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val toastButton = findViewById<Button>(R.id.toastButton)
        toastButton.setOnClickListener {
            Toast.makeText(applicationContext, "This is a longer toast message!", Toast.LENGTH_LONG).show()
        }
    }
}

Expected Output:

This is a longer toast message!

Example 5: Toast with a Custom Layout

package com.example.toastdemo

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.widget.Button
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val customToastButton = findViewById<Button>(R.id.customToastButton)
        customToastButton.setOnClickListener {
            val inflater = layoutInflater
            val layout = inflater.inflate(R.layout.custom_toast, findViewById(R.id.custom_toast_container))

            val text = layout.findViewById<TextView>(R.id.text)
            text.text = "This is a custom Toast!"

            val toast = Toast(applicationContext)
            toast.duration = Toast.LENGTH_LONG
            toast.view = layout
            toast.show()
        }
    }
}

Expected Output:

This is a custom Toast! (with a custom layout)

Common Mistakes

1. Forgetting to call show: A common mistake is to create a Toast but forget to call the show method, resulting in no message appearing on the screen.

Incorrect Code:

   Toast.makeText(applicationContext, "Message without show", Toast.LENGTH_SHORT)

Correct Code:

   Toast.makeText(applicationContext, "Message with show", Toast.LENGTH_SHORT).show()

1. Using the wrong context: Using an incorrect context (e.g., using a fragment context instead of an activity context) can lead to crashes.

Tip: Always use applicationContext unless you're sure which context you need.

Best Practices

• ✅ Keep messages concise: Toast messages should be short and to the point to ensure users quickly understand the feedback.
• ✅ Use appropriate duration: Choose between Toast.LENGTHSHORT and Toast.LENGTHLONG based on the importance of the message.
• ✅ Customize when necessary: If you need a distinct look, consider using a custom layout for your Toast.

Practice Exercises

1. Create a simple app that displays a Toast message when a user clicks a button, but make it display different messages based on which button is clicked.

• ✅ Hint: Use multiple buttons and set onClickListeners for each.

1. Implement a custom Toast layout that includes an image along with the text message.

• ✅ Hint: Design a custom layout XML and inflate it in the Toast.

1. Experiment with different gravity settings to position your Toast messages in various locations on the screen.

• ✅ Hint: Use combinations of Gravity.TOP, Gravity.BOTTOM, Gravity.LEFT, and Gravity.RIGHT.

With this guide, you should now have a solid understanding of how to use Toast messages in your Kotlin Android applications. Happy coding!