Android on Haoxiqiang's Blog

Build AOSP for Pixel 3 XL

Mon, 15 Aug 2022 20:53:06 +0000

The AOSP build process is fairly well understood by now: sync the source code, add device-specific drivers and kernel, and build the target image. I had built AOSP before to debug certain issues, but official support for Pixel 3 XL only goes up to Android 12. Recently, while working on Chromium development, I needed to test WebView on a newer platform, so I used LineageOS 21 for the build instead.

Optimizing Android Builds with Self-Hosted Nexus Repository

Tue, 31 Dec 2019 21:29:27 +0000

In Android dependency management, it’s common to configure multiple remote repositories like jcenter, jitpack, google(), and more. Some large projects, such as “Zuiyou”, depend on over 10 repositories. This becomes a significant problem during initial project setup, dependency changes, or network issues — troubleshooting builds becomes a nightmare.

I had noticed this issue long ago but kept putting off addressing it. This post documents the Nexus setup process.

Installing and Configuring Nexus

Prerequisite: JDK 8+.

Android MediaStore: GROUP BY via ContentResolver

Fri, 31 Mar 2017 11:19:26 +0000

When building a photo album feature similar to WeChat, I needed to read photos and videos with multi-folder switching — and it had to be faster than WeChat. After some research, the MediaStore approach proved most suitable. Since I hadn’t used it much before, this post serves as a record.

The GROUP BY Hack in ContentResolver

ContentResolver.query() does not expose a groupBy parameter (unlike SQLiteQueryBuilder.query()), but you can achieve a similar effect by embedding GROUP BY directly into the selection argument.

Android Issues Roundup (Part 2)

Tue, 19 Jan 2016 16:50:36 +0000

Second batch of collected issues, mainly covering WebView memory management, cookie synchronization, and other development details.

Building an App with RxJava

Thu, 07 Jan 2016 14:05:45 +0000

I’ve been working on a Zhihu Daily client to evaluate RxJava’s benefits and trade-offs in a real project. RxJava has gained significant traction abroad, with language bindings spanning Java, JavaScript, C#, Scala, Clojure, C++, Python, Ruby, Kotlin, Swift, and more.

Android Development Issues and Solutions

Tue, 29 Dec 2015 18:41:05 +0000

After reading some issue roundups on Xiaoke’s Blog, I realized I’ve encountered many of the same problems. Here’s a collected summary.

Android Resource Shrinking

Wed, 23 Dec 2015 17:43:07 +0000

While building a project, I discovered the shrinkResources attribute, which removes unused resources from the APK. Here is how to configure it and what to watch out for.

Tree View Menu with RecyclerView

Wed, 16 Dec 2015 18:15:33 +0000

I had long wanted to write a tree view demo. Previously, I used TreeViewList (a ListView wrapper) or ExpandableListView for multi-level menus. Eventually I realized there is no need for custom views – just use RecyclerView and manage the data flattening yourself.

The core idea: recursively flatten a nested data structure into a linear list, then use notifyItemRangeInserted / notifyItemRangeRemoved to handle expand and collapse.

Solving Problems from Error Logs — Bugly Blog Collection

Wed, 29 Jul 2015 12:00:39 +0000

We use Tencent Bugly for crash monitoring in our project. Most crash reporting tools are similar in functionality; Bugly was chosen for its clean statistics dashboard and reliable brand. Here is a curated collection of Bugly’s technical blog posts covering common crash scenarios and analysis approaches.

Common Issues When Customizing Volley

Tue, 09 Jun 2015 17:30:15 +0000

While integrating Volley into a project, I encountered several common issues worth documenting. The following does not apply to Android 2.3 and below.

Downloading Android Source Code

Thu, 04 Jun 2015 15:45:04 +0000

Timeliness note: The mirror URLs in this article were valid for a specific period. Both TUNA (Tsinghua) and USTC (Hefei) AOSP mirror addresses have changed multiple times. Always consult each mirror’s official help page for current URLs.

AOSP source is enormous (~70GB), making downloads from Google’s official servers via VPN painfully slow. Chinese mirrors offer much faster speeds.

Make Your App the Default SMS App

Mon, 18 May 2015 16:49:21 +0000

While using Google Messenger, I noticed it has a “set as default SMS app” feature. Here’s how it works.

Starting from Android 4.4 KitKat, Google introduced the default SMS app mechanism. The official reasoning:

Some of you have built SMS apps using hidden APIs — a practice we discourage because hidden APIs may be changed or removed and new devices are not tested against them for compatibility. So, to provide you with a fully supported set of APIs for building SMS apps.

In short, if you build well and have enough users, Google takes notice and provides official support.

Notes from Reading Android Documentation

Mon, 11 May 2015 11:18:26 +0000

A collection of subtle but important details I noticed while reading the Android developer documentation.

Dart Web Apps on Android

Tue, 05 May 2015 17:46:58 +0000

Historical note: This article was written in 2015 based on the old Dart toolchain (Dart Editor + Dartium). Dart has since moved entirely to the Flutter ecosystem and the dart CLI toolchain. Content is kept for reference only.

You can launch and debug Android web applications built with Dart without pre-compiling to JavaScript. To do this, you need Dart Editor and Dart Content Shell. Dart Content Shell is automatically installed on the Android device.

Strange Problems I Encountered Recently

Tue, 21 Apr 2015 14:41:34 +0000

A collection of obscure Android development issues and their solutions.

Android Data Storage

Wed, 08 Apr 2015 11:38:49 +0000

Android provides several options for persisting data, each suited to different use cases. Choosing the right storage method is critical for your app’s performance, security, and user experience.

Android App Widgets

Wed, 01 Apr 2015 10:37:26 +0000

An App Widget is a miniature application view that can be embedded into other applications (such as the Home screen) and receive periodic updates. Common examples include weather widgets and music player controls.

Android Developer Requirements

Wed, 01 Apr 2015 09:50:52 +0000

Note: This article was written in 2015. Some toolchain details and version numbers are outdated and provided for historical reference only. For current Android development, please refer to Android Studio and the official Android Developers documentation.

Remote Debugging on Android with Chrome

Tue, 24 Mar 2015 14:54:02 +0000

Chrome DevTools supports remote debugging of web pages and WebView applications on Android devices. This feature is invaluable for mobile front-end development and hybrid app development, allowing you to use the full suite of desktop Chrome DevTools to debug mobile pages.

Bezier Curve Practice

Wed, 04 Mar 2015 14:11:48 +0000

Bézier curves are widely used in computer graphics to model smooth curves. They were independently developed by French engineers Pierre Bézier (Renault) and Paul de Casteljau (Citroën) in the 1960s.

Android Property Animation

Tue, 03 Mar 2015 10:31:21 +0000

Property Animation is a powerful animation framework introduced in Android 3.0 (API 11). Unlike the older View Animation (tween animation) system, property animation actually changes the properties of the target object, not just its rendered appearance.

SQLite Limits Explained: Tracing a SQLiteFullException

Sat, 28 Feb 2015 22:48:55 +0000

While debugging a recent bug, I ran into a peculiar issue: android.database.sqlite.SQLiteFullException: database or disk is full (code 13). After extensive research without a definitive root cause, I am sharing my findings here in the hope that others with similar experiences can help shed light on this.

Android Notification Guide

Thu, 29 Jan 2015 15:26:07 +0000

The notification system is a critical channel for user-app interaction on Android — it keeps users informed of important events even when the app is not in the foreground, such as incoming messages or calendar reminders. Notifications received a major overhaul in Android 4.1 (Jelly Bean) and continued to see refinements through Android 5.0 (Lollipop). Since 4.1, Android supports action buttons at the bottom of notifications, allowing users to perform common tasks directly without opening the app.

Note: This article was written for the Android 4.1–5.0 era APIs. Starting from Android 8.0 (API 26), all notifications must be assigned to a Notification Channel. Android 13 (API 33) introduced the POST_NOTIFICATIONS runtime permission. The code examples below use NotificationCompat for backward compatibility; visual results may vary across devices.

Android Learning Resources Guide

Mon, 26 Jan 2015 16:35:07 +0000

Note: This post was written in 2015. Some links may no longer be valid. The recommendations reflect the ecosystem at that time, but the core learning path and methodology remain relevant.

Foreword

We all start somewhere. For any technology, everyone begins with Hello World. What puzzles me is why some people improve 100% in a year while others only 20% — or even stagnate. Is it IQ? In my opinion, it is more likely a matter of learning method.

While on my wedding leave, I was writing blog posts and searching for learning materials. I found that relying solely on Baidu was terribly inefficient — at least half the time was wasted on useless pages. I decided to spend a few evenings organizing my bookmarks, making sure most resources are accessible from within China. The following is a curated list for beginner-to-intermediate Android developers. As for advanced-level topics — I’m not quite qualified to speak on those yet.

Setting Up Android Environment, Source Code, and Tools Using Chinese Mirrors

Fri, 16 Jan 2015 08:35:07 +0000

Note: This post was written in 2015. Some mirror URLs may have changed or become unavailable. As of 2025, the recommended mirrors for Chinese developers are Tsinghua TUNA, USTC, and other university mirrors, or simply using Android Studio’s built-in SDK Manager.

For developers behind the Great Firewall of China, accessing Google’s servers directly is slow or unreliable. This post covers mirror-based solutions for:

Android SDK updates
Android Studio downloads
AOSP source code downloads
Android NDK downloads

Android Fragment$InstantiationException: Causes and Solutions

Wed, 07 Jan 2015 08:35:07 +0000

1
2

android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment
make sure class name exists, is public, and has an empty constructor that is public

This error used to be rare, but recently it spiked. After investigation, here are the causes and solutions.

Android EBUSY Exception

Mon, 22 Dec 2014 15:35:07 +0000

While working on an image upload feature, I encountered a runtime exception on certain devices:

java.io.FileNotFoundException: /mnt/sdcard/Android/data/com.xxxxxx.android/files/xxxx
    open failed: EBUSY (Device or resource busy)
    at libcore.io.IoBridge.open(IoBridge.java:406)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:88)
    ...
    Caused by: libcore.io.ErrnoException: open failed: EBUSY (Device or resource busy)
    at libcore.io.Posix.open(Native Method)
    at libcore.io.BlockGuardOs.open(BlockGuardOs.java:110)
    ...

Wireless Debugging on Android

Fri, 05 Dec 2014 11:35:07 +0000

Ever since getting a Nexus device, I never wanted to plug in a USB cable again. Android supports ADB debugging over WiFi, making cable-free development a reality.

Android's SQLite

Mon, 01 Dec 2014 22:11:22 +0000

SQLite is a lightweight relational database engine built into Android, ideal for local data persistence. The android.database.sqlite package provides everything you need without additional setup.

Android's Palette

Mon, 03 Nov 2014 10:01:22 +0000

The Palette library, part of Android Support Library (now migrated to AndroidX palette), extracts representative colors from a Bitmap. In Material Design, deriving UI colors from imagery is a common pattern, and Palette makes this straightforward.

Android RecyclerView (Part 2): Parallax Scrolling

Sun, 02 Nov 2014 14:01:22 +0000

Parallax scrolling is a common UI effect where different layers move at different speeds during scrolling, creating a sense of depth.

Android RecyclerView

Sat, 01 Nov 2014 17:03:26 +0000

RecyclerView is a more flexible replacement for ListView. According to the official documentation, it efficiently maintains a limited collection of scrolling data items, and is recommended when your Views need to interact with user gestures and network data.

Android Canvas (Part 2): Clipping

Fri, 03 Oct 2014 14:19:06 +0000

Canvas clipping limits the drawing region: only content within the clipped area is visible.

Android Canvas (Part 1)

Thu, 02 Oct 2014 13:19:06 +0000

A View renders its content by “drawing” — using a canvas (Canvas) and a paintbrush (Paint). The Canvas obtained through the onDraw method is directly composited onto the View.

Android Custom View (Part 2): Measurement Modes

Wed, 01 Oct 2014 19:19:06 +0000

Android Custom View (Part 1)

Wed, 01 Oct 2014 17:19:06 +0000

When you first start writing custom Views in Android, it’s common to feel unsure where to begin. Generally, there are two approaches:

From scratch: Extend View and implement the appearance entirely through calculation and drawing.
Extend an existing View: Add child views to an existing component, or override methods to change its behavior.