Programming Tips & Tricks on Android platform by Sebastian Świerczek - presentation shown during meet.mobile Szczecin in September 2015.

1. Tips & Tricks
Android
Sebastian Świerczek

2. Tips & Tricks list
#1 Gradle libraries versions
#2 Android Support Annotations
#3 Dependencies conflicts resolving
#4 StrictMode
#5 Tools Attributes

3. Gradle libraries
versions
#1

4. Versions for single module
def libVersion = [
support : "23.0.1",
supportTest: "0.4"
]
dependencies {
compile "com.android.support:appcompat-v7:${libVersion.support}"
compile "com.android.support:recyclerview-v7:${libVersion.support}"
androidTestCompile "com.android.support.test:runner:${libVersion.supportTest}"
androidTestCompile "com.android.support.test:rules:${libVersion.supportTest}"
}
#1 Gradle libraries versions
root
> appModule
> build.gradle
> module2
> build.gradle
> build.gradle

5. Versions for all modules
ext {
libVersion = [
support : "23.0.1",
supportTest: "0.4"
]
libDependencies = [
recyclerView : "com.android.support:recyclerview-v7:${libVersion.support}",
appCompat : "com.android.support:appcompat-v7:${libVersion.support}",
supportTestRunner : "com.android.support.test:runner:${libVersion.supportTest}",
supportTestRules : "com.android.support.test:rules:${libVersion.supportTest}"
]
}
#1 Gradle libraries versions
root
> appModule
> build.gradle
> module2
> build.gradle
> build.gradle

6. Versions for all modules
dependencies {
compile libDependencies.recyclerView
compile libDependencies.appCompat
androidTestCompile libDependencies.supportTestRunner
androidTestCompile libDependencies.supportTestRules
}
#1 Gradle libraries versions
root
> appModule
> build.gradle
> module2
> build.gradle
> build.gradle

7. Android Support
Annotations
#2

8. #2 Android Support Annotations
Resource Type Annotations
public void passStringResource(@StringRes int stringResId){...}
public void passColorResource(@ColorRes int colorResId){...}
public void passDrawable(@DrawableRes int drawableResId){...}
public void passColorRgbInt(@ColorInt int rgbColor){...}
public void passStringOrColor(@StringRes @ColorRes int
stringOrColorResId){...}

9. #2 Android Support Annotations
Resource Type Annotations
passStringResource(R.string.app_name);
passStringResource(R.color.black);
passStringResource(1234);

10. #2 Android Support Annotations
Resource Type Annotations
passStringOrColorResource(R.string.app_name);
passStringOrColorResource(android.R.color.white);
passStringOrColorResource(R.drawable.ic_launcher);

11. #2 Android Support Annotations
Resource Type Annotations
passColorRgbInt(resources.getColor(R.color.white));
passColorRgbInt(0xFFFFFFFF);
passColorRgbInt(R.color.white);

12. #2 Android Support Annotations
Typedef Annotations
@IntDef ({
DOWNLOAD_IDLE,
DOWNLOAD_IN_PROGRESS})
public @interface DownloadStatus {}
public static final int DOWNLOAD_IDLE = 0;
public static final int DOWNLOAD_IN_PROGRESS = 1;

13. #2 Android Support Annotations
Typedef Annotations
public void setDownloadStatus(@DownloadStatus int status)
{...}

14. #2 Android Support Annotations
Typedef Annotations
setDownloadStatus(DOWNLOAD_IDLE);
setDownloadStatus(DOWNLOAD_IN_PROGRESS);
setDownloadStatus(1234);

15. Dependencies
conflicts resolving
#3

16. #3 Dependencies conflicts resolving
Google Play Services dependencies conflict
Error:Execution failed for task ':app:processDebugResources'.
> Error: more than one library with package name
'com.google.android.gms'
You can temporarily disable this error with
android.enforceUniquePackageName=false
However, this is temporary and will be enforced in 1.0

17. #3 Dependencies conflicts resolving
Dependencies
compile 'com.google.android.gms:play-services-maps:8.1.0'
compile 'co.realtime:messaging-android:2.1.52'

18. #3 Dependencies conflicts resolving
androidDependencies task to the rescue
./gradlew androidDependencies

19. #3 Dependencies conflicts resolving
androidDependencies task to the rescue
+--- com.google.android.gms:play-services-maps:8.1.0
| --- com.google.android.gms:play-services-base:8.1.0
| --- com.google.android.gms:play-services-basement:8.1.0
| --- com.android.support:support-v4:23.0.1
| --- LOCAL: internal_impl-23.0.1.jar
+--- co.realtime:messaging-android:2.1.52
| +--- LOCAL: json_simple-1.1.jar
| +--- LOCAL: httpcore-4.2.4.jar
| +--- com.google.android.gms:play-services:6.1.71

20. #3 Dependencies conflicts resolving
Fix the issue
compile 'com.google.android.gms:play-services:8.1.0'
compile 'co.realtime:messaging-android:2.1.52'

21. StrictMode
#4

22. #4 StrictMode
Detect UI Thread operations
if (DEBUG) {
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectAll()
.penaltyLog()
.build());
StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder()
.detectAll()
.penaltyLog()
.build());
}

23. #4 StrictMode
Example output
StrictMode policy violation; ~duration=6193 ms:
android.os.StrictMode$StrictModeDiskReadViolation:
policy=31 violation=2
at (…) onReadFromDisk(StrictMode.java:1137)
(…)
at (…) (MainActivity.java:36)

24. Tools Attributes
#5

25. #5 Tools Attributes
Tools Layout Attributes
View in designer.
<FrameLayout (...)
xmlns:tools="http://schemas.android.com/tools">
<TextView (...)
android:text="@string/hello_world"
tools:text="@string/long_text" />
<Button
android:id="@+id/youCanSeeMeAtRuntime"(...)
android:visibility="visible"
tools:visibility="gone" />
</FrameLayout>

26. #5 Tools Attributes
Tools Layout Attributes
View at runtime.

27. #5 Tools Attributes
Tools Layout Pointer
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="@+id/my_fragment"
android:name="com.example.user.exampleapp.MyFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout="@layout/my_fragment_layout" />
</FrameLayout>

28. #5 Tools Attributes
Tools Layout Pointer
Without: With: