Android Intents

Introduction

Intents

There are two types of intents

• Explicit
• Implicit

Explicit

We can start an explicit intent with

val intent = Intent(this.MyActivityClass::class.java_
startActivity(intent)

Implicit

No destination intent is defined. The user will be prompted for which application to use. Not the use of the apply operator.

val intent = Intent().apply {
    action = Intent.ACTION_SEND
    putExtra(Intent.EXTRA_TEXT,"Hello World")
    type = "text/plain"
}
startActivity(intent)

Quite nice compared with the code without the apply.

val intent = Intent()
intent.action = Intent.ACTION_SEND
intent.putExtra(Intent.EXTRA_TEXT,"Hello World")
intent.type = "text/plain"
startActivity(intent)

Implicit With Choice

Android looks at the action, and prompts the user for all app which handle this.The user can make their choice a default however we can override this and force a choice. Notice we should always check for a valid intent or the app will crash

val chooser = Intent.createChooser)myIntent, title)
if(intent.resolveActivity(packageManager) !=null) {
  startActivity(chooser)
} else {
  Log.d(...)
}

Common Intents

What is Required

For common intents we need to go to https://developer.android.com/guide/components/intents-common#Clock and look at what is required this includes

• Action Type
• Permissions
• Sample Code
• Pass the appropriate Parameter

Working Example

This creates an alarm for Mon-Fri at 17:00.

• Set Permissions
• Implementation

Set Permissions

<uses-permission android:name="com.android.alarm.permission.SET_ALARM"/>

Implementation

        val intent = Intent(AlarmClock.ACTION_SET_ALARM).apply {
            putExtra(AlarmClock.EXTRA_MESSAGE, "My Great Alarm")
            putExtra(AlarmClock.EXTRA_HOUR, 17)
            putExtra(AlarmClock.EXTRA_MINUTES, 0)
            putExtra(
                AlarmClock.EXTRA_DAYS, arrayListOf(
                    arrayOf(
                        java.util.Calendar.MONDAY,
                        java.util.Calendar.TUESDAY,
                        java.util.Calendar.WEDNESDAY,
                        java.util.Calendar.THURSDAY,
                        java.util.Calendar.FRIDAY
                    )
                )
            )
        }

        if (intent.resolveActivity(packageManager) != null) {
            startActivity(intent)
        }