kotlin 147 lines · 2 tabs

App widgets for home screen

Alex Chen Jan 2026

2 tabs

package com.example.myapp.widget

import android.app.PendingIntent
import android.appwidget.AppWidgetManager
import android.appwidget.AppWidgetProvider
import android.content.Context
import android.content.Intent
import android.widget.RemoteViews
import com.example.myapp.R
import com.example.myapp.ui.MainActivity

class PostsWidget : AppWidgetProvider() {

    override fun onUpdate(
        context: Context,
        appWidgetManager: AppWidgetManager,
        appWidgetIds: IntArray
    ) {
        appWidgetIds.forEach { appWidgetId ->
            updateAppWidget(context, appWidgetManager, appWidgetId)
        }
    }

    override fun onEnabled(context: Context) {
        // First widget added - perform initial setup
    }

    override fun onDisabled(context: Context) {
        // Last widget removed - cleanup
    }

    companion object {
        fun updateAppWidget(
            context: Context,
            appWidgetManager: AppWidgetManager,
            appWidgetId: Int
        ) {
            // Create an Intent to launch MainActivity
            val pendingIntent: PendingIntent = Intent(context, MainActivity::class.java)
                .let { intent ->
                    PendingIntent.getActivity(
                        context,
                        0,
                        intent,
                        PendingIntent.FLAG_IMMUTABLE
                    )
                }

            // Create refresh intent
            val refreshIntent = Intent(context, PostsWidget::class.java).apply {
                action = AppWidgetManager.ACTION_APPWIDGET_UPDATE
                putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, intArrayOf(appWidgetId))
            }

            val refreshPendingIntent = PendingIntent.getBroadcast(
                context,
                0,
                refreshIntent,
                PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT
            )

            val views = RemoteViews(context.packageName, R.layout.widget_posts).apply {
                setOnClickPendingIntent(R.id.widget_container, pendingIntent)
                setOnClickPendingIntent(R.id.refresh_button, refreshPendingIntent)

                // Set collection adapter for list
                val listIntent = Intent(context, PostsWidgetService::class.java).apply {
                    putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId)
                }
                setRemoteAdapter(R.id.widget_list, listIntent)

                // Set empty view
                setEmptyView(R.id.widget_list, R.id.empty_view)
            }

            appWidgetManager.updateAppWidget(appWidgetId, views)
            appWidgetManager.notifyAppWidgetViewDataChanged(appWidgetId, R.id.widget_list)
        }
    }
}

package com.example.myapp.widget

import android.content.Context
import android.content.Intent
import android.widget.RemoteViews
import android.widget.RemoteViewsService
import com.example.myapp.R
import com.example.myapp.data.repository.PostRepository

class PostsWidgetService : RemoteViewsService() {
    override fun onGetViewFactory(intent: Intent): RemoteViewsFactory {
        return PostsRemoteViewsFactory(this.applicationContext)
    }
}

class PostsRemoteViewsFactory(
    private val context: Context
) : RemoteViewsService.RemoteViewsFactory {

    private var posts: List<Post> = emptyList()

    override fun onCreate() {
        // Setup
    }

    override fun onDataSetChanged() {
        // Fetch data - this runs on UI thread but can be synchronous
        // In real app, fetch from repository
        posts = getDummyPosts()
    }

    override fun onDestroy() {
        posts = emptyList()
    }

    override fun getCount(): Int = posts.size

    override fun getViewAt(position: Int): RemoteViews {
        val post = posts[position]

        return RemoteViews(context.packageName, R.layout.widget_post_item).apply {
            setTextViewText(R.id.post_title, post.title)
            setTextViewText(R.id.post_author, post.author)

            // Set click intent
            val fillInIntent = Intent().apply {
                putExtra("post_id", post.id)
            }
            setOnClickFillInIntent(R.id.post_item, fillInIntent)
        }
    }

    override fun getLoadingView(): RemoteViews? = null

    override fun getViewTypeCount(): Int = 1

    override fun getItemId(position: Int): Long = posts[position].id.toLong()

    override fun hasStableIds(): Boolean = true

    private fun getDummyPosts(): List<Post> {
        return listOf(
            Post(1, "Post 1", "Body", "Author 1", 0L),
            Post(2, "Post 2", "Body", "Author 2", 0L)
        )
    }
}

2 files · kotlin Explain with highlit

App Widgets display app content on the home screen. I extend AppWidgetProvider, a BroadcastReceiver subclass handling widget lifecycle. onUpdate() refreshes widget UI, onEnabled() initializes on first widget added, onDisabled() cleans up when last removed. RemoteViews builds UI since widgets run in launcher process—limited to specific layouts and views. AppWidgetManager updates widgets with updateAppWidget(). Configuration activities customize widgets before placement. Pending intents enable click handling. Collections use RemoteViewsService for ListView or GridView. Widgets update via alarms, broadcasts, or WorkManager. They provide glanceable information and quick actions without opening the app.

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