List of Android Tips

A curated list of awesome Android Tips. Feel free to contrubute.

Other Awesome List

• awesome-android
• awesome-android-ui
• awesome-android-libraries

Index

• Android Studio
  • Keyboard shortcuts
  • Gradle
  • Plugins
  • Live Templates
  • Postfix code completion
• Tools
• Gradle
• UI/UX
• About Me

Android Studio

Keyboard shortcuts

Complete Keymap Guide : MacOSX | Linux/Win

Plugins

Gradle Plugin

Live Templates

• newInstance - Generates the static newInstance function inside a Fragment
• const - Define a android style int constant
• psf - public static final
• visible - Set view visibility to VISIBLE
• gone - Set view visibility to GONE
• noInstance - private empty constructor to prohibit instance creation

Comprehensive list of all Live Templates: https://github.com/keyboardsurfer/idea-live-templates

Postfix code completion

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>.nootnull 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 at: Settings → Editor → Postfix Templates

Tools

Mock

• 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.

Gradle

• 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 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

• 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'
  }

  Checkout more gradle tips here

• Use different package name for non-release builds

    android {
        buildTypes {
            debug {
                applicationIdSuffix '.debug'
                versionNameSuffix '-DEBUG'
            }
  
            release {
                // ...
            }
        }
    }

• If you’re creating a gradient in xml with a part being completely transparent, be really careful when using @android:color/transparent

• Follow a standard naming convention for your resources

• 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

• Stop a running gradle build process

  ./gradlew -stop

• Donot include both jcenter() & mavenCentral() in your build.gradle file

  JCenter is a superset of MavenCentral. [Ref tweet]

• Clear your gradle cache if you think that bundled support and google play services lib in android sdk are inconsistent

  • Goto ~/.gradle/caches/ and delete everything inside the cache folder.
  • Open SDK Manager and resync all support libs and google play services
  • Next re-sync your project
  • Everything should become consistent and functional.

• Setup handy adb aliases for your terminal [Ref Link]

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

  Alias	Usage
  alias screenshot="adb exec-out screencap -p > screen-$(date -j "+%s").png"	screenshot
  `alias startintent="adb devices	tail -n +2
  `alias apkinstall="adb devices	tail -n +2
  `alias rmapp="adb devices	tail -n +2
  `alias clearapp="adb devices	tail -n +2

• 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.

• Use adb install -g to grant all permissions listed in the manifest [More Info]

• Use alfi to find the gradle dependency statement for a library

  Its basically the command line version of Gradle, Please which is a web hosted.

  • Run

    alfi name_of_library

  • Copy the desired library

  • Paste in your build.gradle

• Use dryrun to test a library directly

  • Just Run

    dryrun REMOTE_GIT_URL

• 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
        }
      }
    }

• Reduce installed app size with "android:extractNativeLibs:false" in <application> [Ref Link]

  This will essentially prevent the system from creating a second copy of the .so files and fix the System.loadLibrary call so it’s able to find and open native libs straight from the APK, no code changes on your part required.

• Selectivily execute a specific method in Android Studio [Ref Link]

  

• Did you get one of these Google Play Developer Policy Violation Emails? Worry not, generate a Privacy Policy for your android app [Ref ink]

  • Take a look at App Privacy Policy Generator, a web app to generate a generic privacy policy for your app.

• 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

• Activity LifeCycle [Ref Link]

  

• Tip about onSaveInstanceState()
onSaveInstanceState() is called only when the OS decides to kill the Activity instance. It will not be called when Activity is explicitly killed i.e User pressed back button or finish() is called from code.

• Read about whats in an APK here

• Learn about various techniques involved when using ADB

• Input some text in an editfield in a running emulator from your keyboard

  adb shell input text "keyboard text"

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

• Don't hard-code encryption keys, a simple grep for "Ljavax/crypto" reveals them in bytecode [Ref Link]

• Intents have a limited payload size (1Mb), don't serialize and attach entire file to it [Ref Link]

• Always copy a file before sending it as intent URI. Receiving app could edit it & send a canceled result [Ref Link]

• Use http:// as scheme for app deeplinks, they are more universal & when app not installed drive users to a domain you own [Ref Link]

• Use below to display your app launch time [Ref Link]

  adb shell am start -W <packagename>/. <activityname>

• 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")
  }

• Use activity-alias or your launcher icons will disappear when renaming/moving your MainActivity

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]

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

• 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

About Me

• Github: https://github.com/thanhtoan1196
• Facebook: https://www.facebook.com/thanhtoan1196
• Email: [email protected]

License

Copyright 2017 Toan Tran

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.