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Cheatsheet about tips and tricks for Android Development

This is a simple set of tips and tricks regarding Android Development which I have gathered from various sources. It helps me direct other android devs in my community regarding stuff each android dev should know about. It is also there for me to keep track of anything I either learn on my own or from other sources now and then when browsing the internet.

Contributions are always welcome, hoping people will help me in growing this. To contribute, simply open up a PR with the changes.

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Credits

This curated cheatsheet includes tips and tricks that I have been following in my workflow as well as those being suggested/followed by other android devs worldwide.I have tried to add direct links wherever I could remember, giving people due credit who have explained the concepts. If you think I have missed any, then either send a PR or open an issue and I will fix it asap.

If you appreciate my work, consider buying me a cup of ☕️ to keep me recharged 🤘🏼 [PayPal]

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Code faster by using keyboard shortcuts

DescriptionMacLinux/Win
Lookup IDE commands / ActionsCmd Shift ACtrl Shift A
Open ClassCmd OCtrl O
Open FileCmd Shift OCtrl Shift N
Open recently edited fileCmd Shift ECtrl Shift E
Open SymbolCmd Opt OAlt Shift N
Open recently used fileCmd ECtrl E
Last Edited LocationCmd Shift BackspaceCtrl Shift Backspace
Find Usage in persistent windowOpt F7Alt F7
Find Usage in floating windowCmd Opt F7Ctrl Alt F7
Format the code with proper IndentationCmd Opt LCtrl Alt L
Surround WithOpt Cmd TAlt Ctrl T
Open TerminalOpt F12Alt F12
Generate Setter/GettersCmd NAlt Ins
Find ClassCMD OCtrl N
Refactor/RenameShift F6Shift F6
Quick FixOpt EnterAlt Enter
Goto DefinitionCmd BCtrl B
Show parameters for selected methodCmd PCtrl P
Refactor ThisCtrl TCtrl Alt Shift T
Stop ProcessCmd F2Ctrl F2
Search EverywhereShift ShiftShift Shift
Select Methods to OverrideCtrl OCtrl O
Delete LineCmd BackspaceCtrl Y
Duplicate LineCmd DCtrl D
Grow/Shrink selection from cursorOpt Up/Down Arrow keyShift Ctrl W
Multicursor SelectionCtrl GAlt J

Complete Keymap Guide : Linux/Win | MacOSX

Other Tips/Tricks

  • Did you know you can quickly lookup the definition of any function by navigating to the function call and using Opt + Space on macOS or Alt + Space on Win/Linux inside Android Studio🙀 [Ref Tweet]

    quicklookup_def

  • Annoyed by the Design view always opening up when you open a layout or drawable xml file?🙄Navigate to Preferences ▶️Editor ▶️Layout Editor and choose "Code" option, to always open in Code view. [Ref Tweet]

    always_use_code_view

  • If you want to use keyboard shortcuts with bookmarks, then make use of "Bookmark with Mnemonic". Once assigned a number, you can jump to the bookmark using Ctrl + Number. [Ref Tweet]

    bookmarks_mnemonic_as

  • When working with a class file dat has a lot of loc, often times one needs to jump between some parts of the same file. To do that, one can use the "Bookmarks" in Android Studio! Simply mark the line of code as Bookmark & open up the Bookmark Panel to jump. [Ref Tweet]

    bookmarks_as

  • Bunch of quick tips about refactoring under this blogpost I wrote for raywenderlich.com

Use plugins to become more efficient

  1. KeyPromoter X

    The plugin basically will annoy the hell out of you by showing you a big screen overlay with the key combination you should have used, if you used your mouse to execute some command to a level when you basically would start using the key combination just to avoid KeyPromoter annoying you all the time. It also has some useful features, like it will prompt you to create a key binding for a command whenever an action does not have a key binding and you have used it 3 times using your cursor. [ Old Version: KeyPromoter]

  2. String Manipulation

    Provides actions for text manipulation such as Toggle case, encode/decode, sorting,

  3. Lines Sorter

    Add Sort Lines action in Edit menu to sort selected lines or whole file if the selection is empty.

  4. Findbugs

    Provides static byte code analysis to look for bugs in Java code from within Android Studio

  5. Sonar Lint

    The plugin that provides on-the-fly feedback to developers on new bugs and quality issues injected into Java, JavaScript and PHP code.

  6. Checkstyles

    The plugin provides both real-time and on-demand scanning of Java files from within Android Studio.

  7. ADB Idea

    The plugin that adds ADB commands to Android Studio and IntelliJ such as ADB Uninstall App, ADB Kill App, ADB Restart App, etc

  8. Exynap

    The plugin which helps you find and implement the code you require in an instant.

  9. Dagger IntelliJ Plugin

    The Dagger IntelliJ plugin creates visual connections between a @Inject object and the @Provides method that creates it.

  10. JVM Debugger Memory View

    This plugin extends the built-in JVM debugger with capabilities to explore objects in the JVM heap during a debug session.

  11. Android Parcelable code generator

    Plugin which generates Android Parcelable boilerplate code for you.

Speed code using code-completion

Use Live Templates in Android Studio

  • newInstance - Generates the static newInstance function inside a Fragment

  • Toast - Generates Toast.makeText(context, "", Toast.LENGTH_SHORT).show();

  • fbc - findViewById with cast

  • const - Define a android style int constant

  • logd - Generates Log.d(TAG, "");

  • logm - Log current method name and its arguments.

  • logr - Log result of the current method

  • logt - static logtaf with current classname

  • psf - public static final

  • sout - Prints a string to System.out

  • soutm - Prints current class and method names to System.out

  • soutp - Prints method parameter names and values to System.out

  • visible - Set view visibility to VISIBLE

  • gone - Set view visibility to GONE

  • noInstance - private empty constructor to prohibit instance creation

  • There is a quick way to surround your layout with a Linear Layout via using a Live Template. You can create one called wrapll by setting it up [Ref Link]

    live_template_wrapll_2 live_template_wrapll_3

    ...and use it as below

    live_template_wrapll_1

    You can create more based on your usecase 😄

Comprehensive list of all Live Templates in Android Studio

Postfix code completion in Android Studio

Android Studio/IntelliJ havea special kind of code completion which allows you to write code specific to a field

  • <expr>.null will auto complete to if(<expr> == null)

  • <expr>.notnull will auto complete to if(<expr> != null)

  • <expr>.var will auto complete to T name = <expr>

  • <expr>.field will auto complete to create a global field variable field = <expr>

  • <ArrayExpr>.for will auto complete to for(T item : <Arrayexpr>)

  • <ArrayExpr>.fori will auto complete to

    for(int i = 0; i < <Arrayexpr>.length; i++)

  • <ArrayExpr>.forr will auto complete to

    for(int i = <Arrayexpr>.length - 1; i > 0 ; i--)

Complete list of available postfix code completion can be found via navigating inside Android Studio/IntelliJ menu:

Settings → Editor → Postfix Templates

Configuring Android Studio

Use the Darcula Theme in Android Studio

Ok, I know its more like a preference, but trust me using that keeps your eyes less strained as they would be if you used the Default Light theme.

Don't use a small font

Preferably use a font in Android Studio that's easy to read and is at a font size which does not forces you to strain your eyes. Also using fonts that support lingature increases readeablity. While everyone has a preferred font, below are some options for interested folks:

Use a code style

You should use a standard codestyle, so possible contenders can be

Misc tips

ADB Shell

Few handy commands you can use to interact with emulator/device, through terminal.

DescriptionCommand
List all connected devicesadb devices
Install an application on device
-s to install on the SD Card
-g to grant all permissions listed in the manifest [More Info]
adb install -r ~/application.apk
Uninstall an applicationadb uninstall your.app.package
Download a file from deviceadb pull /sdcard/file.ext
Upload a file to a deviceadb push file.ext /sdcard
Print all installed packages on deviceadb shell pm list packages -f
Clear Application dataadb shell pm clear your.app.package
Toggle Data for deviceadb shell svc data disable
Toggle Wifi for deviceadb shell svc wifi enable
Location of Device
- High accuracy: gps,wifi,network or gps,network (if you want the wifi)
- Battery saving: wifi,network or network only
- Device only: gps
adb shell settings put secure location_providers_allowed gps
Reset all granted permissionsadb shell pm reset-permissions -p your.app.package
Reset a specific permissionadb shell pm revoke your.app.package android.permission.WRITE_EXTERNAL_STORAGE
Broadcast Actionsadb shell am broadcast -a 'my_action'
Simulating Android killing your app in the backgroundadb shell am kill
Take a Screenshotadb shell screencap -p \| perl -pe 's/\x0D\x0A/\x0A/g' > screenshot.png
Launch an installed app using its package nameadb shell monkey -p com.yourapp.packagename 1
Stress test your app using its package name by sending a pseudo-random stream of user events into the systemadb shell monkey -p com.yourapp.packagename -v 500

Setup ADB Aliases

Append the below Aliases to your ~/.bashrc or ~/.zshrc file, save and restart the terminal. Once saved, use them as show in Usage column

#############################################################
# Android aliases + path
#############################################################

# Path to Android SDK (This is for Mac, replace for your OS)
export ANDROID_HOME=$HOME/Library/Android/sdk

# Path to NDK
export ANDROID_NDK_HOME=$ANDROID_HOME/ndk

# Path to Android platform tools (adb, fastboot, etc)
export ANDROID_PLATFORM_TOOLS="$ANDROID_HOME/platform-tools"

# Path to Android tools (monitor, mksdcard, emulator-check, emulator, etc)
export ANDROID_TOOLS_1="$ANDROID_HOME/tools"

# Path to Android tools (apkanalyzer, avdmanager, monkeyrunner, lint, sdkmanager etc)
export ANDROID_TOOLS_2="$ANDROID_HOME/tools/bin"

# Path to Android tools (aapt, apksigner, zipalign, etc)
export ANDROID_TOOLS_3="$ANDROID_HOME/build-tools/29.0.3/"

# Add all to the path
export PATH="$PATH:$ANDROID_PLATFORM_TOOLS:$ANDROID_TOOLS:$ANDROID_TOOLS_2:$ANDROID_TOOLS_3"

# Demo Mode : https://android.googlesource.com/platform/frameworks/base/+/master/packages/SystemUI/docs/demo_mode.md
# Enable Demo Mode on your device
# Usage: enableDemoMode
alias enableDemoMode="adb shell settings put global sysui_demo_allowed 1 && adb shell am broadcast -a com.android.systemui.demo -e command clock -e hhmm 1200 && adb shell am broadcast -a com.android.systemui.demo -e command network -e mobile show -e level 4 -e datatype false && adb shell am broadcast -a com.android.systemui.demo -e command notifications -e visible false && adb shell am broadcast -a com.android.systemui.demo -e command battery -e plugged false -e level 100"

# Disable Demo Mode on your device
# Usage: disableDemoMode
alias disableDemoMode="adb shell am broadcast -a com.android.systemui.demo -e command exit"

# Install and Grant all permissions for an apk
# Usage: grantAllPermissionsForApk path/to/apk/Application.apk
alias grantAllPermissionsForApk="adb install -g $1"

# Take a screenshot
# Usage: screenshot
alias screenshot="adb exec-out screencap -p > screen-$(date -j "+%s").png"

# Fire an intent
# Usage: startintent https://twitter.com/nisrulz
alias startintent="adb devices | tail -n +2 | cut -sf 1 | xargs -I X adb -s X shell am start $1"

# Install Apk
# Usage: apkinstall ~/path/to/apk/App.apk
alias apkinstall="adb devices | tail -n +2 | cut -sf 1 | xargs -I X adb -s X install -r $1"

# Uninstall an app
# Usage: rmapp com.example.demoapp
alias rmapp="adb devices | tail -n +2 | cut -sf 1 | xargs -I X adb -s X uninstall $1"

# Clear all data of an app
# Usage: clearapp com.example.demoapp
alias clearapp="adb devices | tail -n +2 | cut -sf 1 | xargs -I X adb -s X shell pm clear $1"

# Get package name of the passed apk file
# Usage: getPackageName app-debug.apk
alias getPackageName="apkanalyzer -h manifest application-id $1"

# Stress test the debug apk with 100000 ui events
# Execute at the root of your android project
# Use as: stressTestDebugApk apk_file.apk
function stressTestApk() {
    local APP_PACKAGE_NAME=$(getPackageName $1)
    adb shell monkey -p $APP_PACKAGE_NAME 100000
}

# Install APK to device
# Use as: apkinstall app-debug.apk
alias apkinstall="adb devices | tail -n +2 | cut -sf 1 | xargs -I X adb -s X install -r $1"

# As an alternative to apkinstall, you can also do just ./gradlew installDebug
# Alias for building and installing the apk to connected device
# Use as: buildAndInstallApk path/to/apk_file.apk
# Example: To build and install debug apk
#        > buildAndInstallApk  ./app/build/outputs/apk/debug/app-debug.apk
alias buildAndInstallApk="./gradlew assembleDebug && apkinstall $1"

# Launch your apk on your connected device
# Execute at the root of your android project
# Usage: launchApk path/to/apk_file.apk
# Example: To launch debug apk
#        > launchApk  ./app/build/outputs/apk/debug/app-debug.apk
alias launchApk="adb shell monkey -p $(getPackageName $1) 1"

# ------------- Single command to build+install+launch apk------------#
# Execute at the root of your android project
# Use as: buildInstallLaunchApk path/to/apk_file.apk
# Example: To build, install and launch debug apk
#        > buildInstallLaunchApk  ./app/build/outputs/apk/debug/app-debug.apk
alias buildInstallLaunchApk="buildAndInstallApk $1 && launchDebugApk $1"

scrcpy

It is basically used to display and control your Android device and is the open source equivalent of Vysor. The good folks at Genymotion built this tool and then open sourced it (Open Source FTW).

Working with gradle wrapper

  • To force re-download of dependencies

    ./gradlew --refresh-dependencies
    
  • To exclude a certain task from being run by gradle

    Suppose you want to exclude the task javaDoc then use -x option followed by the task name, i.e javaDoc in this case.

    ./gradlew clean build -x javaDoc
    
  • Stop a running gradle build process

    ./gradlew -stop
    
  • Upgrade gradle wrapper to latest release version i.e 6.5

    Run this inside your project folder via terminal

    ./gradlew wrapper --gradle-version 6.5 --distribution-type all
    
  • Make use of Build Cache to speed up your builds.

    Set the below property in your global gradle.properties file

    android.enableBuildCache=true
    
  • Make your builds faster by building offline [Ref Link]

    The --offline flag tells gradle to always use dependency modules from the cache, regardless if they are due to be checked again. When running offline, gradle will never attempt to access the network to perform dependency resolution. If required modules are not present in the dependency cache, build execution will fail.

    • Assembling develop debug at full speed:

      ./gradlew assembleDevelopDebug --offline
      
    • Running your unit tests at full speed:

      ./gradlew test --offline
      
  • Run a single unit test from the command line using the --tests option e.g: ./gradlew testDebugUnitTest --tests "*.MainPresenterTest" . Use * to avoid typing the entire package name. [Ref Link]

Gradle: Groovy Script Tricks

  • Use proguard

    android {
      ...
      buildTypes {
          release {
              minifyEnabled true
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
    }
    

    [Read more from the manual here]

  • Use shrinkResources

    android {
      ...
      buildTypes {
          release {
              shrinkResources true
              minifyEnabled true
              ...
          }
      }
    }
    
  • Split your apk using gradle when using Native code, do not bundle all of em together and ship!.. coz that will make you evil

    defaultConfig {
        ...
    
        ndk {
          abiFilters "armeabi", "armeabi-v7a", "mips", "x86"
        }
      }
    
    //Split into platform dependent APK
    splits {
      abi {
        enable true
        reset()
        include 'armeabi', 'armeabi-v7a', 'mips', 'x86' //select ABIs to build APKs for
        universalApk false //generate an additional APK that contains all the ABIs
      }
    }
    
    // map for the version code
    project.ext.versionCodes = ['armeabi': 1, 'armeabi-v7a': 2, 'mips': 5, 'x86': 8]
    
    // Rename with proper versioning
    android.applicationVariants.all { variant ->
      // assign different version code for each output
      variant.outputs.each { output ->
        output.versionCodeOverride =
            project.ext.versionCodes.get(output.getFilter(com.android.build.OutputFile.ABI), 0) *
                1000000 +
                android.defaultConfig.versionCode
      }
    }
    
  • To have the each subproject script name match that of the project name

    Then add this line in settings.gradle

    rootProject.children.each{
      it.buildFileName = it.name + '.gradle'
    }
    
  • Use different package name for non-release builds

      android {
          buildTypes {
              debug {
                  applicationIdSuffix '.debug'
                  versionNameSuffix '-DEBUG'
              }
    
              release {
                  // ...
              }
          }
      }
    
  • Setup Android Studio to fail build if code contains //STOPSHIP [Ref Link]

    To enable the //STOPSHIP lint check, in your build.gradle

    android {
    ...
        lintOptions {
            abortOnError true
            fatal 'StopShip'
        }
    }
    

    If you have a //STOPSHIP comment in your code, this will cause an error to be thrown when a release apk is generated.

    You can turn on //STOPSHIP highlighting in Android Studio (isn't enabled by default) in

    Preferences > Editor > Code Style > Inspections.

    Search for STOPSHIP to find the correct setting.

  • Output unit tests directly to the console [Ref Link]

    A small neat trick to see Android unit tests logging results as they happen in the terminal.

    android {
        ...
        testOptions.unitTests.all {
          testLogging {
            events 'passed', 'skipped', 'failed', 'standardOut', 'standardError'
            outputs.upToDateWhen { false }
            showStandardStreams = true
          }
        }
      }
    
  • Define a variable at build time In your build.gradle

    android{
      defaultConfig {
        ...
        buildConfigField "String", "SERVER_ENDPOINT", '"http://www.myendpoint.com"'
        buildConfigField "int", "FOO", "52"
        buildConfigField "boolean", "LOG", "false"
        ...
      }
    }
    

    and then use it in code as BuildConfig.SERVER_ENDPOINT, BuildConfig.FOO,BuildConfig.LOG

  • Calculate the version code and version name in your build.gradle manually, based of version values In your app's build.gradle

    versionMajor = 0
    versionMinor = 0
    versionPatch = 0
    versionBuild = 1
    
    verCode = versionMajor _ 1000000 + versionMinor _ 10000 + versionPatch \* 100 + versionBuild
    verName = "${versionMajor}.${versionMinor}.${versionPatch}"
    
    // Use
    android{
      defaultConfig {
            ...
            versionCode verCode
            versionName verName
            ...
      }
    }
    
  • Calculate the version code and version name in your build.gradle automatically, based on git information

    Note: These functions go specifically inside the app's build.gradle and cannot be used with ext.

    In your app's build.gradle

    // Version code is calculated as the number of commits from last commit on master
    def getVersionCode = { ->
      try {
        def code = new ByteArrayOutputStream()
        exec {
          commandLine 'git', 'rev-list', 'HEAD', '--count'
          standardOutput = code
        }
        return Integer.parseInt(code.toString().trim())
      } catch (exception) {
        return "1";
      }
    }
    
    // Version name is Last Tag Name + No. of commits form last Tag +  short git sha
    def getVersionName = { ->
      try {
        def stdout = new ByteArrayOutputStream()
        exec {
          commandLine 'git', 'describe', '--tags', '--dirty'
          standardOutput = stdout
        }
        return stdout.toString().trim()
      } catch (exception) {
        return "0.0.0.1";
      }
    }
    
    // Use
    android{
      defaultConfig {
        ...
        versionCode getVersionCode()
        versionName getVersionName()
        ...
      }
    }
    
  • Get the date of build as a variable In your app's build.gradle

    // Get the date of build
    def getDateOfBuild = { -> // ISO 8601 time format
      return new Date().format("yyyy-MM-dd'T'HH:mm'Z'").toString().trim()
    }
    
    // then use it as a variable in BuildConfig
    android{
      defaultConfig {
        ...
        buildConfigField "String", "DATE_OF_BUILD", "\"${getDateOfBuild()}\""
      }
    }
    
  • Get the Git SHA as a variable In your app's build.gradle

    // Get the last Git Short Hash
    def getGitHash = { ->
      def stdout = new ByteArrayOutputStream()
      exec {
        commandLine 'git', 'rev-parse', '--short', 'HEAD'
        standardOutput = stdout
      }
      return stdout.toString().trim()
    }
    
    // then use it as a variable in BuildConfig
    android{
      defaultConfig {
        ...
        buildConfigField "String", "GIT_SHA", "\"${getGitHash()}\""
      }
    }
    

    Have a look at the Paperwork Project, which generates build info for your Android project without breaking incremental compilation

  • Use Java 8 features by adding sourceCompatibility & targetCompatibility to your build.gradle file

    android {
      ...
      compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
      }
    }
    
  • Setup a gradle task to archive apks and proguard files on build, for backup purposes

    task deployApks(type:Copy) {
        description = "Copies APKs and Proguard mappings to the deploy directory"
        def appName = "<app_name>";
        def versionDir = android.defaultConfig.versionName+"_"+android.defaultConfig.versionCode;
    
        println("Copies APK and Proguard to " + versionDir)
    
        from 'build/outputs/mapping/release/'
        include '**/mapping.txt'
        into '../.admin/deploy/' + versionDir
        rename ('mapping.txt', "${versionDir}-mapping.txt")
    
        from ('.') {
            exclude '**/build', '**/src'
        }
    
        include '*.apk'
        into '../.admin/deploy/' + versionDir
        rename ('app-release.apk', "${appName}-${versionDir}.apk")
    }
    
  • Reference local aar files as below [Stackoverflow Ref]

      dependencies {
         implementation(name:'nameOfYourAARFileWithoutExtension', ext:'aar')
      }
      repositories {
         flatDir {
            dirs 'libs'
         }
      }
    
  • Get faster gradle builds by only using one resource configuration for your development builds [Ref Link]

    android {
      ...
      productFlavors {
        dev {
          ...
          // The following configuration limits the "dev" flavor to using
          // English stringresources and xxhdpi screen-density resources.
          resConfigs "en", "xxhdpi"
        }
        ...
      }
    }
    
  • Specifying buildToolsVersion in your build.gradle files is optional when using Android plugin 3.0.0 or later. By default the plugin uses the minimum version of the build tools required by the version of the plugin you're using. [Tweet Link, Ref Link]

    dont_specify_buildtoolsversion

  • You can insert variables into AndroidManifest defined in build.gradle [Tweet Link, Ref Link]

    inject_vars_in_manifest

  • Make use of custom gradle tasks in your build.gradle files

    Android uses Gradle as its build system, which actually allows one to make a lot of things easy by creating tasks to automate things. This reddit post enlists a lot of such useful gradle scripts

Gradle: Kotlin Script Tricks

Work in Progress

Make better choices while coding

  • Google released an option to include OSS license activity in your app, use that to attribute credits to the OSS libs in your app [Ref Link]

    Checkout a working example here

  • Make Android Studio render <merge> layouts correctly by specifying the layout type with the tools:parentTag attribute [Ref Link]

    diagram

  • Checkout the Background Execution Limits on Android Oreo and update your app to work with the restrictions [Ref Link]

  • To take good screenshots with clean status bar use the Demo Mode in Android [Ref Link]

    • Steps

      1. Enable Demo Mode

        adb shell settings put global sysui_demo_allowed 1
        
      2. Enable/disable icons by running the right command

        // display time 12:00
        adb shell am broadcast -a com.android.systemui.demo -e command clock -e hhmm 1200
        
        // Display full mobile data without type
        adb shell am broadcast -a com.android.systemui.demo -e command network -e mobile show -e level 4 -e datatype false
        
        // Hide notifications
        adb shell am broadcast -a com.android.systemui.demo -e command notifications -e visible false
        
        // Show full battery but not in charging state
        adb shell am broadcast -a com.android.systemui.demo -e command battery -e plugged false -e level 100
        
      3. Run app and take screenshots

      4. Exit demo mode once you are done

        adb shell am broadcast -a com.android.systemui.demo -e command exit
        
  • To record video of your android device [Ref Link]

    adb shell && screenrecord /sdcard/download/fileName.mp4
    

    Hit Ctrl+C to exit/stop recording

    Recorded video file is saved at the location mentioned in the command on the device itself.

  • Use Dao inheritance to reduce the amount of boilerplate code [Ref Link]

  • Instead of using getActivity() in fragment, keep a habit of getting context from onAttach(). [Ref Link]

  • Avoid setting a background in every view/fragment as it likely causes overdraw. [Ref Link]

  • View.getWidth() = 0? That's because your view hasn't been layout yet, use globallayoutListener to know layout done. [Ref Link]

  • Android never kills activities, it only kills processes. When low memory the lowest priority ranked will be killed.[Ref Link]

  • Use .([filename].java:[line]) in your log statements to make them clickable in Android Studio and Intellij IDEA.

  • Use -whyareyoukeeping class com.jeroenmols.MyClass to figure out why certain a class wasn't removed.[Ref Link]

  • Use certificate pinning to resist impersonation by attackers using mis-issued or otherwise fraudulent certificates, when making requests from your app. [Ref Link]

  • Do download the latest emulator using CLI

    cd <android_sdk>/tools/bin
    ./sdkmanager --channel=3 emulator
    

    To check the version of emulator, use ./sdkmanager --channel=3 emulator

  • Checkout some tricks when using Android Strings in XML

  • Cleanup your Gradle caches by deleting files not accessed within the last month [Ref Link]

    find ~/.gradle -type f -atime +30 -delete
    find ~/.gradle -type d -mindepth 1 -empty -delete
    

    To check the size of your gradle cache, run: du -sh ~/.gradle

  • Checkout some cool tricks when using tools: attribute in your android layouts, such as sample data and recyclerview item layout previews

  • Remove all debug log statements from the release build using the below proguard rules. (app's build.gradle should have minifyEnabled true set for this to work)

    # Remove all debug logs
    -assumenosideeffects class android.util.Log {
        public static *** d(...);
    }
    

    The above snippet is usually appended to contents of app/proguard-rules.pro file

  • Should I use Enums in Android?

    tl;dr

    • If you need code to be very performant integer constants may be the way to go

      public class Operator {
          public static final int ADD = 1;
          public static final int SUBTRACT = 2;
          public static final int MULTIPLY = 3;
          public static final int DIVIDE = 4;
      }
      
    • Use Enums because

      • Are type-safe, so you can only use valid enum types
      • Provide better code readability
      • Can implement interfaces
      • Support polymorphic behavior
      • In some really trivial cases, Proguard can optimize Enums into integer constants for you [Ref Link]
      • Performance difference rarely makes a difference.
      public enum Operators {
          Add, Subtract, Multiply, Divide
      }
      
  • The string resource android.R.string.yes doesnot yield string "Yes" instead it yields "Ok". Similarly the string resource android.R.string.no doesnot yield string "No" instead it yields "Cancel" [Ref Link]

    string resource

  • Don’t want generated files in your AS search results? Go to Preferences -> File Types -> Ignore files and folders and add the pattern to ignore - e.g. *.dex;*.class; [Ref Link]

  • If you uncheck “Suspend” and check “Evaluate and Log” in breakpoint menu, the breakpoint will print evaluated statement into the uncluttered “Console” window. No need for recompile due to added Log.d statements anymore [Ref Link]

    Breakpoint Logs

  • To measure how long a method took to execute, you can use TimingLogger class. [Ref Link]

    • Typical Usage
      TimingLogger timings = new TimingLogger(TAG, "methodA");
      // ... do some work A ...
      timings.addSplit("work A");
      // ... do some work B ...
      timings.addSplit("work B");
      // ... do some work C ...
      timings.addSplit("work C");
      timings.dumpToLog();
      
    • Output
      D/TAG     ( 3459): methodA: begin
      D/TAG     ( 3459): methodA:      9 ms, work A
      D/TAG     ( 3459): methodA:      1 ms, work B
      D/TAG     ( 3459): methodA:      6 ms, work C
      D/TAG     ( 3459): methodA: end, 16 ms
      
  • If you're working with Android Things and you don't have an extrenal screen for your device, install scrcpy and use it to see what's going on your Android IoT device. It works a charm over wireless adb. [Ref Link]

  • Android Studio has this weird behaviour that it allows to edit its default code style, which leads to a weird side-effect. If you open your pre-setup project(with set codestyle and copyright configs) in Android Studio it will delete all pre-setup codestyle and copyright profile in this project. This is every much evident if you checked in your configs into git for sharing purpose, which is lost immediately as soon as you open the project

    deleted:    .idea/codeStyles/Project.xml
    deleted:    .idea/codeStyles/codeStyleConfig.xml
    deleted:    .idea/copyright/profiles_settings.xml
    deleted:    .idea/copyright/copyright.xml
    

    To fix that please follow along as below: [All thanks to Said Tahsin Dane for the solution]

    • We first need to verify that your Default codestyle isn't modified. To check that please open Android Studio with any project except your pre-setup(with set codestyle and copyright configs) project. Then navigate to Preferences>Edior>Codestyle and check if your code scheme has Default in BLUE color (this means it is modified).

      modified_default

    • However if it is not colored BLUE, you are good and you can go ahead to open your pre-setup(with set codestyle and copyright configs) project and everything should be pre-setup for you.

    • If it is modified (colored BLUE), then click on the cog icon and select Restore Default

      restore_default

    • After you hit that option, simply accept the change

      accept_change

    • Once done, you will see your Default is no more colored BLUE or modified, which means you are good

      unmodified_default

    • Now simply go ahead and open your pre-setup(with set codestyle and copyright configs) project and everything should be pre-setup for you.

  • If you add android:sharedUserId to an already published app, the app data will be cleared for all users that install your upgrade (because Android changes the process). So if you ever intend to use it, you must add it before publishing your app [Ref Link]

  • When opening up methods for testing, use otherwise to still hide it from code complete.[Tweet Link, Ref Link]

    making_methods_visible_for_testing

  • You can group your recent Android Studio projects, and add icons to them [Ref Link]

    group_recent_projects

  • Only build a single configuration to speed up debug builds. [Ref Link]

    build_single_config

  • Avoid the annoying jump to Design tab while editing XML. Prefer XML editor under Settings [Ref Link]

    set_xml_as_preferred

  • Reduce installed app size with android:extractNativeLibs="false" in [Tweet Link, Ref Link]

  • Improve Android Studio code inspections with Thread annotations [Tweet Link, Ref Link]

  • Use adb to put a phone into doze mode for testing [Tweet Link, Ref Link]

  • Use areNotificationsEnabled() from NotificationManagerCompat to detect whether your users blocked your Notifications [Tweet Link, Ref Link]

  • Activity.runOnUiThread is just a convenient wrapper of Handler.post; don't pass around Activity just so you can use it. [Ref Link]

  • Define your interfaces with the highest possible option that will suffice. Don't use an Activity when a Context will do. [Ref Link]

  • If you're not building a replacement for the dialer, use ACTION_DIAL not ACTION_CALL to initiate a call. [Ref Link]

  • Requesting updates from a system service may drain battery, so register for updates in onResume and unregister in onPause. [Ref Link]

  • Hierarchy Viewer won’t run on prod devices, if however u want to run it then follow below steps [Tweet Link, Ref Link]

    running_hierarchy_viewer

  • Variable and init block declaration order in Kotlin, actually matters :) if you want to use a variable inside init {} initialize it before it.

  • When comparing intents it does not compare any extra data included in the intents [Tweet Link, Ref Link]

  • To show a ringtone picker to the user, use the ACTION_RINGTONE_PICKER intent to launch the picker as a subactivity. [Ref Link]

  • Want to remove focusState on an item in GridView? Try: android:listSelector="#00000000" [Ref Link]

  • You can generate the proguard keep rules via the APK Analyzer inside Android Studio. [Ref Link]

    proguard_rules_apk_analyzer

  • When viewing an Android Manifest, there is a tab at the bottom that allows you to see the merged manifest. Use this to inspect the merged manifest and find conflicts. [Ref Link]

    manifest-merged

  • In the APK analyzer in Android Studio, classes/members listed in italic are only references, not definitions. If it's in italics, it's defined in another DEX file (or the SDK). [Ref Link]

    apk_analyzer_ref

  • To be able to write multiline Todo comments, simply indent by 1 tab from second line onwards. [Ref Link]

    multiline_todo_comment

  • You can get rid of a lot of noise in the Logcat, by Right Clicking a selected text > "Fold lines like this" option!. [Ref Link]

    fold_line_like_this

  • You know how you can group ur code inside IDEs such as Android Studio and IntelliJ IDEA by using the region and endregion comment blocks. Turns out you can use the same trick to group inside XML files such as for layout, strings, styles, colors xml files [Ref Tweet]

    region_cmt

  • How many of you have had issue with special characters (&,<, >, etc) in your strings.xml file? Did you know there is an action called "Encode XML/HTML Special Characters" inside Android Studio that can escape those characters for you! [Ref Tweet]

    encode_special_1

    • The option is also avaliable under Edit menu drop down

      encode_special_2

    • In case the issue is in just one line, you can also just ALT+ENTER to get contextual fix.

      encode_special_3

Tips regarding UI/UX

  • Motion

    • Material Design uses real-world metaphors as its foundation. Objects in the real world don't move linearly, they move in curved paths and accelerate and decelerate according to the motion's properties.
    • As such, motion should also use such properties and animate objects so that the motion feels natural rather than forced
    • For example, a car leaving the screen in a movie starts off slowly, then accelerates till it's out of the frame. Similarly, views should be interpolated using classes like AccelerateInterpolator, FastOutSlowInInterpolator, etc. [More Info]
    • When changing the visibilities of views, if you add android:animateLayoutChanges="true" to the parent, you get a nice little animation for free. [Ref Link]
  • Typography

    • While custom typefaces can be used for branding, it is essential to stick to Roboto and Noto if possible, especially for body text, due to their clarity and optimistic nature.
    • Roboto covers Latin, Greek and Cyrillic extended scripts, with Noto filling in for other language scripts [More Info]
    • Weight balancing is an important aspect of typography, the fundamental concept of which is that the larger a typeface is, the less its weight should be so that it doesn't appear too thick and balances its weight with smaller typefaces of higher weights
    • Typography should align to a 4dp baseline grid, and maintain a minimum contrast ratio of 4.5:1 based on luminance values, with a recommended ratio being 7:1.
    • The ideal reading length for large blocks of text is 40 to 60 characters per line. Anything less is too narrow and anything more is too wide.
  • Icons

    • Icons should be designed at 48dp, with 1dp edges, which equates to
      • 48px by 48px at mdpi
      • 72px by 72px at hdpi
      • 96px by 96px at xhdpi
      • 144px by 144px at xxhdpi
      • 192px by 192px at xxxhdpi
    • An additional icon of 512px by 512px should be designed for use on Google Play
    • Material icons, in addition to the base icon, should contain the following important elements
      • 1dp tinted edge at the top
      • 1dp shaded edge at the bottom
      • Contact shadow - a soft shadow around all edges of raised elements
      • Finish - a soft tint to provide surface lighting, fading from upper life to lower right [More Info]
  • Ripples

    • When implementing Ripple Effect use ?attr/selectableItemBackground instead of ?android:attr (Ref)

    • When implementing Ripples contained within the view like Button, use (Ref)

      android:background="?attr/selectableItemBackground"
      
    • When implementing Ripples that extend beyond the view's bounds like ImageView: (Ref)

      ?attr/selectableItemBackgroundBorderless
      
  • Other Points to Note
    • Views should be aligned to Material Design's 8dp baseline grid and the keylines when possible. This gives the UI a sense of structure and hierarchy. [More Info]
    • If you plan on keeping a reference to any ViewGroup (LinearLayout, FrameLayout, RelativeLayout, etc.), and you don’t want to use any methods specific to this particular type of Layout, keep it as a ViewGroup object. [More Info]
    • While picking an accent color (if the brand already has one), pick a color complementary to the primary color so that the contrast is high enough

Tips if you use Kotlin

Podcasts to listen

  1. Fragmented
  2. Android Developers Backstage

There are others too, but the above two are the popular ones, you can lookup more using tag android on sites offering Podcast Services.

P.S : I use Player.fm to listen to these podcasts. They even have an Android Client, all for FREE.

Learning Resources

Examples to learn from

Make use of Helper tools

  • Android SVG to VectorDrawable - One VectorDrawable to rule all screen densities

  • SQLite Viewer - View sqlite file online

  • Android 9-patch shadow generator - Tool that makes fully customizable shadows possible

  • APK method count - Tool that outputs per-package method counts

  • Material Palette - Easily generate the color pallete based on material design

  • Color Tool - Create, share and apply color palettes to your UI

  • Javadoc Themer - Give your boooring javadocs a splash of colors!

  • Method Count - Use this tool to avoid the dreaded 65K method limit of the DEX file format!

  • Gradle, please - Lookup dependency reference name to include as your gradle dependencies

  • jsonschema2pojo - Generate Plain Old Java Objects from JSON or JSON-Schema

  • Android Asset Studio - A web-based set of tools for generating graphics and other assets that would eventually be in an Android application's res/ directory.

  • Device Art Generator - Quickly wrap app screenshots in device artwork

  • Google Translator Toolkit - Translate strings.xml files to any language and download as XML

  • JSONViewer - Awesome JSON formatter

  • ShapeShifter - SVG path morphing animation editor.

  • App Privacy Policy Generator - Generate a generic privacy policy for your app for the playstore.

  • gnirehtet - Reverse tethering for Android.

  • Adaptive Icons - Try out the new Adaptive Icons in your browser

  • Android Starters - Handcrafted starter projects, optimized for simplicity and ease of use.

  • Language Switcher Tile - An android plugin that allows you to easily change your device language.

  • Flipper - Flipper is a platform for debugging mobile apps on iOS and Android. Visualize, inspect, and control your apps from a simple desktop interface.

  • Use freely available mockable api points

    • Mockey - A tool for testing application interactions over http, with a focus on testing web services, specifically web applications that consume XML, JSON, and HTML.
    • JSON Placeholder - Fake Online REST API for Testing and Prototyping
    • API Studio - a playground for API developers
    • Mocky - Mock your HTTP responses to test your REST API
    • Mockbin - Mockbin allows you to generate custom endpoints to test, mock, and track HTTP requests & responses between libraries, sockets and APIs.
  • ADB/Fastboot Tools made available as a separate package by google, download latest version for

  • Awesome android libraries

    • StorIO - Beautiful API for SQLiteDatabase and ContentResolver
    • Retrofit - Type-safe HTTP client for Android and Java by Square, Inc.
    • Picasso - A powerful image downloading and caching library for Android
    • LeakCanary - A memory leak detection library for Android and Java.
    • AndroidViewAnimations - Cute view animation collection.
    • Calligraphy - Custom fonts in Android the easy way.
    • Alerter - Android Alerting Library