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TOOLS Sebastiano Poggi Novoda, Android GDE TRADE OF THE #toolsOfTrade

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1.3 Android Studio

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“How can this be a NPE?” “I wish things were strongly typed, all resource IDs look like any other integer!”

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“How can this be a NPE?” “I wish things were strongly typed, all resource IDs look like any other integer!” “Why isn’t this text R.color.red? It’s showing as black!”

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“How can this be a NPE?” “I wish things were strongly typed, all resource IDs look like any other integer!” “Why isn’t this text R.color.red? It’s showing as black!” “I love Eclipse!”

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“How can this be a NPE?” “I wish things were strongly typed, all resource IDs look like any other integer!” “Why isn’t this text R.color.red? It’s showing as black!” “I love Eclipse!” “What? I thought this was on the

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“How can this be a NPE?” “I wish things were strongly typed, all resource IDs look like any other integer!” “Why isn’t this text R.color.red? It’s showing as black!” “I love Eclipse!” “What? I thought this was on the UI thread, but it’s crashing”

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Great news!*

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Great news!*

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Great news!* Annotations and XML attributes will save the day

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SURPRISE QUESTION Lint

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Lint Born in 1979 for C

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Lint Born in 1979 for C Performs static code analysis

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Lint Born in 1979 for C Performs static code analysis Should be part of your CI builds

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Lint Born in 1979 for C Performs static code analysis Should be part of your CI builds

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tools xmlns:

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tools xmlns: namespac

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tools xmlns: namespace Built into the SDK/Android Studio

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tools namespace Built into the SDK/Android Studio Safe to commit under VCS

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tools namespace Built into the SDK/Android Studio Safe to commit under VCS (Usually)

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tools namespace Built into the SDK/Android Studio Safe to commit under VCS (Usually)

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tools:text="Hello world!"

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Design-time overrides Override any android attribute /> tools:text="Hello world!"

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Tools attributes Lint attributes

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Tools attributes Lint attributes Design attributes

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Tools attributes Lint attributes Design attributes

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Tools attributes Lint attributes Design attributes

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Should explicitly set allowBackup… Lint attribute: ignore Similar to @SuppressWarnings

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/>

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tools:ignore="AllowBackup" tools:ignore="AllowBackup"

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... Lint attribute: targetApi Equivalent to @TargetApi /> <item android:elevation="8dp" tools:targetApi="HONEYCOMB" android:elevation requires API level 21(current min is 19)

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... Lint attribute: targetApi Equivalent to @TargetApi /> <item android:elevation="8dp" tools:targetApi="LOLLIPOP" /> android:elevation requires API level 21(current min is 19)

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... Lint attribute: targetApi Equivalent to @TargetApi <item android:elevation="8dp" tools:targetApi="LOLLIPOP" />

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Helo, I am a typo. > tools:locale="en">

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Helo, I am a typo. tools:locale="en">

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Tools attributes Lint attributes Design attributes

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> tools:context=".map.MapActivity"

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> tools:context=".map.MapActivity"

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>

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> tools:showIn="@layout/activity_main"

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> Design attribute: showIn Shows a merge in its parent layout’s include

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> tools:menu="map"

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> Design attribute: menu Shows a menu in the layout preview

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> tools:actionBarNavMode="tabs"

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> Design attribute: actionBarNavMode Shows navigation in the action bar …in theory

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tools:layout="@layout/fragment_main"

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Design attribute: layout Previews a fragment’s layout

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Design attributes: list* Previews a ListView’s items, header and footer

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Good read Tools of the Trade by Yours Truly https://goo.gl/hZv6S5 https://goo.gl/sia3ms

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Good read Tools attributes http://goo.gl/lzd6YP

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Support annotations Require support-annotations dependency

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Support annotations Require support-annotations dependency Design attributes support-v4 (and thus v7) depends on it

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Support annotations Require support-annotations dependency support-v4 (and thus v7) depends on it

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public static String trim( return what.trim(); Nullability annotations @Nullable and @NonNull String what) { @Nullable }

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Nullability annotations @Nullable and @NonNull String what) { @Nullable public static String trim( return what.trim(); Method invocation may produce NullPointerException }

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public static String trim( if (what == null) {
 return "";
 
 return what.trim();
 Nullability annotations @Nullable and @NonNull String what) { } } @NonNull

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Nullability annotations @Nullable and @NonNull String what) { @NonNull } } public static String trim( if (what == null) {
 return "";
 
 return what.trim();
 Condition 'what == null' is always 'false'

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setMainTextColor(R.color.text_color);
 
 void setMainTextColor(
 textView.setTextColor(getColor(colorId)); Resource ID annotations A lot of @{resType}Res that enforce typing @Nullable Should pass resolved color instead of resource ID } int colorId) {

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setMainTextColor(R.color.text_color);
 
 void setMainTextColor(
 textView.setTextColor(getColor(colorId)); Resource ID annotations A lot of @{resType}Res that enforce typing @Nullable int colorId) { } @ColorRes

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Resource ID annotations @AnimatorRes @AnimRes @AnyRes @ArrayRes @AttrRes @BoolRes @ColorRes @DimenRes @DrawableRes @FractionRes @IdRes @IntegerRes @InterpolatorRes @LayoutRes @MenuRes @PluralsRes @RawRes @StringRes @StyleableRes @StyleRes @XmlRes

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setTextColor(R.color.text_color);
 
 private void setTextColor(
 ... RGB Color annotation @ColorInt requires color value, not ID } int color) { @ColorInt

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setTextColor(R.color.text_color);
 
 private void setTextColor(
 ... RGB Color annotation @ColorInt requires color value, not ID } @ColorInt int color) { Should pass resolved color instead of resource id here

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setValue(20); 
 void setValue(
 // Value must be in [0, 10] Range annotations @FloatRange and @IntRange } int value) { @IntRange(from=0, to=10)

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setValue(20); 
 void setValue(
 // Value must be in [0, 10] Range annotations @FloatRange and @IntRange } int value) { @IntRange(from=0, to=10) Value must be ≥ 0 and ≤ 10 (was 20)

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Range annotations setCoords(new int[]{42}); 
 void setCoords(
 // Value must be int[2] @Size for arrays, collections and strings } int[] value) { @Size(2) Value must be ≥ 0 and ≤ 10 (was 20)

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Range annotations setCoords(new int[]{42}); 
 void setCoords(
 // Value must be int[2] @Size for arrays, collections and strings } int[] value) { @Size(2) Value must be ≥ 0 and ≤ 10 (was 20) Size must be exactly 2

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int style; TypeDef annotations The issue with avoiding enums @IntRange(from=0, to=10) static final int STYLE_MATERIAL = 0;
 static final int STYLE_HOLOYOLO = 1; style = 21;

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@IntDef(value={STYLE_MATERIAL, STYLE_HOLOYOLO})
 @Retention(RetentionPolicy.SOURCE)
 @interface Style { } TypeDef annotations @interface definition: @IntDef and @StringDef @IntRange(from=0, to=10) static final int STYLE_MATERIAL = 0;
 static final int STYLE_HOLOYOLO = 1;

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style = 21; TypeDef annotations @interface usage @IntRange(from=0, to=10) Must be one of: STYLE_MATERIAL, STYLE_HOLOYOLO static final int STYLE_MATERIAL = 0;
 static final int STYLE_HOLOYOLO = 1; int style; @Style

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static final int STYLE_MATERIAL = 0;
 static final int STYLE_HOLOYOLO = 1; TypeDef annotations @interface usage @IntRange(from=0, to=10) @Style int style; style = 21; Must be one of: STYLE_MATERIAL, STYLE_HOLOYOLO

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Threading annotations Specify thread “affinity” for methods private void test() {
 textView.setText("Oops!"); @WorkerThread }

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Threading annotations Specify thread “affinity” for methods private void test() {
 textView.setText("Oops!"); @WorkerThread Method setText must be called from the UI thread, currently inferred thread is worker }

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Threading annotations Specify thread “affinity” for methods Method setText must be called from the UI thread, currently inferred thread is worker @MainThread @BinderThread @UiThread @WorkerThread

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“Architecture” annotations Contracts for methods invocation and overriding @CallSuper @CheckResult @VisibleForTesting

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Permissions annotations Specifies calling a method requires a permission startBluetoothScan(); @RequiresPermission(Manifest.permission.BLUETOOTH) private void startBluetoothScan() { ... }

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Permissions annotations Specifies calling a method requires a permission @RequiresPermission(Manifest.permission.BLUETOOTH) startBluetoothScan(); private void startBluetoothScan() { ... } Missing permissions required by startBluetoothScan: android.permission.BLUETOOTH

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Proguard annotation Specifies a symbol should be kept by Proguard @Keep private void myMethod() { ... }

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Good read Improving Code Inspection with Annotations https://goo.gl/QLyf10

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Good read Support annotations http://goo.gl/3DTImU

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A & Q

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View debugging BONUS ROUND

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View debugging Built into the SDK since API 1

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View debugging Built into the SDK since API 1 ViewDebug

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View debugging Built into the SDK since API 1 ViewDebug

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public class MyCustomView extends View {
 private int fancyColor; Exported view properties Use @ExportedProperty @Nullable public int getFancyColor() {
 return fancyColor; } @ViewDebug.ExportedProperty

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public class MyCustomView extends View {
 private int fancyColor; Exported view properties Use @ExportedProperty @Nullable @ViewDebug.ExportedProperty public int getFancyColor() {
 return fancyColor; }

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Exported view properties Use @ExportedProperty @Nullable (
 category = "My category"
 ) public int getFancyColor() {
 return fancyColor; } @ViewDebug.ExportedProperty

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Good read ViewDebug JavaDoc http://goo.gl/v54umV

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A & Q (for real this time) (also, tweet questions @seebrock3r)

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Thank you! @seebrock3r +SebastianoPoggi rock3r Sebastiano Poggi Novoda, Android GDE #toolsOfTrade