How to Create Buttons Inside a Widget in Android?

Prerequisites

• How to Create a Basic Widget of an Android App?
• How to Create a Dynamic Widget of an Android App?

A Widget is a mini version of an Application, that provides a ground for the user to navigate through it or use its features from the Home Screen or Lock Screen. Widgets contain elements according to the features it provides. Widgets, as previously termed a mini version of the Application, is capable of displaying similar elements that of an Application, through this article, let’s demonstrate the implementation of Buttons and correspondingly how they can be used for certain functionalities. Here is a preview of the same:

Steps for Creating Buttons Inside a Widget

Step 1: Create a New Project

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Kotlin as the programming language.

Step 2: Add the App Widget to the Project

• Right-Click on the app, move the cursor to new, find the “Widget” option at the end, select it.

• Specify the required properties for the widget such as min.width and height, config file and preferred language, etc, and proceed. Files are automatically generated.

Step 3: What to program? Where to program?

1. In our application, since we wish to display two Buttons named “Activity1” & “Activity2“, we need to declare them inside the new_app_widget.xml file which is inside the Layouts in the Resources folder.
2. The entire programming (back-end) is done in the newly created NewAppWidget.kt, Kotlin Class File in the Main Source Folder. Here, we construct the Buttons. Since these Buttons will redirect the users to different activities, we need to create two Empty Activities, we name them “Activity1” and “Activity2” respectively.
3. These Activities serve as Pending Intents since they initialize only when the user clicks on one of the buttons.
4. Changes are made to Activity 1 and Activity 2 front-end files to represent their names.
5. Just refer to the below codes and the corresponding comments given below.

• new_app_widget.xml and NewAppWidget.kt files

XML

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#0F9D58"
    android:padding="@dimen/widget_margin">

    <!-- Button 1 -->
    <Button
        android:id="@+id/btn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Activity1"
        android:layout_centerInParent="true"
        />

    <!-- Button 2 -->
    <Button
        android:id="@+id/btn2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Activity2"
        android:layout_centerHorizontal="true"
        android:layout_below="@id/btn1"
        />

</RelativeLayout>

Kotlin

package org.geeksforgeeks.widget_buttons

import android.app.PendingIntent
import android.appwidget.AppWidgetManager
import android.appwidget.AppWidgetProvider
import android.content.Context
import android.content.Intent
import android.widget.RemoteViews


// Implementation of App Widget functionality
class NewAppWidget : AppWidgetProvider() {
    override fun onUpdate(
        context: Context,
        appWidgetManager: AppWidgetManager,
        appWidgetIds: IntArray
    ) {
        // There may be multiple widgets active, so update all of them
        for (appWidgetId in appWidgetIds) {
            updateAppWidget(context, appWidgetManager, appWidgetId)
        }
    }

    // Enter relevant functionality for when
      // the first widget is created
    override fun onEnabled(context: Context) {

    }

    // Enter relevant functionality for when
      // the last widget is disabled
    override fun onDisabled(context: Context) {

    }

}

internal fun updateAppWidget(
    context: Context,
    appWidgetManager: AppWidgetManager,
    appWidgetId: Int
)

/////////////////////////////Start Coding Here///////////////////////////////////////
{

    // Create a pending Intent for Activity 1
    val i1 : PendingIntent = Intent(context,Activity1::class.java).let { intent ->
        PendingIntent.getActivity(context, 0, intent, 0)  }

    // Create a pending Intent for Activity 2
    val i2 : PendingIntent = Intent(context,Activity2::class.java).let { intent ->
        PendingIntent.getActivity(context, 0, intent, 0)  }

    // Construct the RemoteViews object
    val views = RemoteViews(context.packageName, R.layout.new_app_widget)
        // Button 1 onClick Function
        .apply{setOnClickPendingIntent(R.id.btn1,i1)}
        // Button 2 onClick Function
        .apply { setOnClickPendingIntent(R.id.btn2,i2) }

    // Instruct the widget manager to update the widget
    appWidgetManager.updateAppWidget(appWidgetId, views)
}
/////////////////////////////Code Ends Here///////////////////////////////////////

• activity_1.xml, Activity1.kt, activity_2.xml, Activity2.kt files

In both, the XML files add only a TextView, and in the Kotlin files, we have added nothing. The users may write their own code as their requirements inside those files.

XML

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Activity1">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Activity 1"
        android:layout_centerInParent="true"
        />

</RelativeLayout>

Kotlin

package org.geeksforgeeks.widget_buttons

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class Activity1 : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_1)
    }
}

XML

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Activity2">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Activity 2"
        android:layout_centerInParent="true"
        />

</RelativeLayout>

Kotlin

package org.geeksforgeeks.widget_buttons

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class Activity2 : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_2)
    }
}

• activity_main.xml, MainActivity.kt files

There is nothing to do inside the activity_main.xml, MainActivity.kt files. The users may write their own code as their requirements inside those files.

XML

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Kotlin

package org.geeksforgeeks.widget_buttons

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

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

Output: Run on Emulator