Code to go Android

Compilation tools ■  Technologies: ■  Java, XML, SQLite, OpenGL, embedded development ■  Tools ■  Eclipse (and Android Studio, based on IntelliJ IDE) ■  Android SDK ■  Platform libraries ©2012 Immersion Corporation–Confidential

Using Eclipse ■  Eclipse video tutorials http://eclipsetutorial.sourceforge.net/totalbeginner.html http://www.vogella.de/articles/Eclipse/article.html ■  Eclipse “Perspective” reset Window > Reset Perspective > Yes ©2012 Immersion Corporation–Confidential

What if I did not download any platforms? Then do it now. Download Platform 14, and use that throughout. In Eclipse, click on Window > Android SDK Manager Running your Studio Project Under “Android 4.0 (API 14) Click on “SDK Platform” Then click “Install” These are large 100MB downloads – don’t download more than you need till you are back on your home network ©2012 Immersion Corporation–Confidential

What if I did not put the SDK tools in my path? Take a demerit for Gryffindor, and add the folders now. MacOS – edit file ~/.bash_profile to add these 2 directories to PATH by adding this at the end of the file (use names for your PC!) Running your Studio Project export PATH=$PATH:/Users/plinden/android-sdk-macosx/ tools:/Users/plinden/android-sdk-macosx/platform-tools! Linux – add the SDK two folders, tools and platform-tools, to your PATH in your shell initialization file (file varies with the shell you use). Windows – path environment variable is set somewhere under control panel. Google “Windows 7 set env variable” (windows 8 etc) ©2012 Immersion Corporation–Confidential

Files that make up a Mobile App ■  Java files ■  Resource files ■  Png files for icons (up to 5 different screen resolutions) ■  XML files to specify the GUI layout and controls ■  XML files to hold literal strings ■  A project manifest file in XML ■  Asset files (photos, music, video…, other files not compiled or localized) ©2012 Immersion Corporation–Confidential

Ingredients of an App •  Source code for every Android app has: AndroidManifest.xml describes the app overall, features used, version, etc Java “glue” XML, icons Media, data files, etc •  App binary is an .apk file (zip format) •  contains the compiled version of these files ©2012 Immersion Corporation–Confidential

The “Top 2 folders” – src, res ■  Java files ■  Resource files ■  Png files for icons (1-5 dpi’s) { ■  XML files for GUI layout ■  XML files to hold literal strings ■  A project manifest file in XML ■  Restriction: filenames under res folder must contain only lowercase a-z, 0-9, or _. ©2012 Immersion Corporation–Confidential

GUIs in Android Views (Widgets, Controls) ■  E.g. Button, CheckBox, TextView, ProgressBar, ■  About 70 basic controls Layouts ■  Defines where each View is on a screen ■  One XML file per screen ■  “alternative resources” – diff layout for portrait vs land Event handlers ■  When a user “operates” a View, it fires an event ■  Developer writes event handler code to process it ©2012 Immersion Corporation–Confidential

GUIs in Android - diagram Layout Views Event Handlers open_db(); take_pic(); §  how it looks §  what events it fires §  specified in XML in a layout file §  position on screen §  specified in XML file §  the Activity sets this file as its “content view” (how it looks) ©2012 Immersion Corporation–Confidential §  what happens when view is clicked §  written in Java

Peter’s handy-dandy XML cheat-sheet What it’s called What it looks like Declaration <?xml version="1.0" encoding="utf-8"?> Element <someTagName attributes> nested_elements </someTagName> Element <someTagName attributes /> Attribute someName=“someValue” Comment  Android namespace declaration xmlns:android= "http://schemas.android.com/apk/res/android" Attribute name from android namespace android:layout_width="fill_parent" ©2012 Immersion Corporation–Confidential

Getting into XML §  There is an XML file defining the GUI objects on its screen/ Activity <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent” > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello” /> </LinearLayout> ©2012 Immersion Corporation–Confidential

XML for a View §  Every View must have a value for android:layout_width and _height Tells layout manager how much room you want for the WIDTH and the HEIGHT of the component §  "fill_parent” magic word that says “greedy – as much as possible” “match_parent” is also used. §  "wrap_content” magic word that says “frugal – as little as possible” <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello” /> ©2012 Immersion Corporation–Confidential

Gluing XML names to Java code The XML names in res folder are visible in Java namespace! The glue code is generated for you. Create an ID name for an XML element with this attribute <TextView android:id="@+id/myTV" In Java, get hold of that XML-declared TextView by: TextView tv = (TextView) ﬁndViewById( R.id.myTV ); In XML, get hold of that XML-declared TextView by: <Button android:layout_below=”@id/myTV" ©2012 Immersion Corporation–Confidential

android.widget.TextView ■  Appearance: ■  XML in res/layout/myname.xml <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:background="#0FF" android:text="width is wrap_content" /> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#FF0000" android:text="width is fill_parent" /> ©2012 Immersion Corporation–Confidential

Easy to make mistakes! ■  Appearance: XML in res/layout/myname.xml <TextView android:layout_width="wrap_content" android:layout_height=”fill_parent" android:background="#0FF" android:text="width is wrap_content" /> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:background="#FF0000" android:text="width is fill_parent" /> ©2012 Immersion Corporation–Confidential

Attributes for android.widget.TextView ■  Use the Android Developer Docs ■  http://developer.android.com/reference/android/R.styleable.html#TextView ■  There are about 75 attributes for TextView ©2012 Immersion Corporation–Confidential

android.widget.Button ■  Appearance: disabled enabled ■  XML <Button android:layout_width="fill_parent" android:layout_height="wrap_content” android:text="@string/brew" android:id="@+id/bt" /> ©2012 Immersion Corporation–Confidential pressed

android.widget.EditText ■  Appearance: <EditText a someAttributes /> ■  Subclass of TextView ■  No new attributes of its own ■  Requires the usual layout attribs ■  Click in the field to get keyboard ■  And type away… ©2012 Immersion Corporation–Confidential

android.widget.EditText Event Handler ■  Gives you the contents of entire field for each keypress ■  Implement android.view.View.OnKeyListener ■  Only has 1 method: onKey(View v, int keyCode, KeyEvent event) ■  Register your listener with: myedittext.setOnKeyListener( objOnKeyListener ); ©2012 Immersion Corporation–Confidential

android.widget.EditText key listener public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); final EditText et = (EditText) findViewById(R.id.et); OKL my_okl = new OKL(); et.setOnKeyListener(my_okl); } } class OKL implements OnKeyListener { public boolean onKey(View v, int keyCode, KeyEvent event) { if ((event.getAction() == KeyEvent.ACTION_DOWN) && (keyCode == KeyEvent.KEYCODE_ENTER)) { // Perform action only for "return" key press EditText et = (EditText) v; Log.i("Hi app", et.getText().toString()); return true; // have "consumed event" } return false; // have not consumed event } } ©2012 Immersion Corporation–Confidential

android.widget.Button ■  Gives you an event when clicked ■  Implement android.view.View.OnClickListener ■  Only has 1 method: onClick(View v) ■  Register your listener with code: mybutton.setOnClickListener( objOnClickListener); ■  Or register your listener with XML attribute: <Button … android.onClick=“doAction” /> public void doAction(View v) { … } ©2012 Immersion Corporation–Confidential

android.widget.Button event handler public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); final Button bt = (Button)findViewById(R.id.bt); CL my_cl = new CL(); bt.setOnClickListener(my_cl); } public void doAction(View v) { // button has been pressed Log.i("Hi app", v.toString() + " pressed,doAction called"); } class CL implements OnClickListener { public void onClick(View v) { Log.i("Hi app", v.toString() + " pressed"); } } ©2012 Immersion Corporation–Confidential

Always have “adb logcat” running in a terminal! 01-22 18:31:30.520 11946 11946 W dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x40018560) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: FATAL EXCEPTION: main 01-22 18:31:30.559 11946 11946 E AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hi/ com.example.hi.HiActivity}: android.view.InflateException: Binary XML file line #7: Error inflating class Checkbox 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1696) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1716) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.app.ActivityThread.access$1500(ActivityThread.java:124) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:968) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:99) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.os.Looper.loop(Looper.java:130) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:3806) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at java.lang.reflect.Method.invokeNative(Native Method) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:507) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at dalvik.system.NativeStart.main(Native Method) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class Checkbox 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:581) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.view.LayoutInflater.rInflate(LayoutInflater.java:623) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.view.LayoutInflater.inflate(LayoutInflater.java:408) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.view.LayoutInflater.inflate(LayoutInflater.java:320) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.view.LayoutInflater.inflate(LayoutInflater.java:276) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:256) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.app.Activity.setContentView(Activity.java:1703) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at com.example.hi.HiActivity.onCreate(HiActivity.java:19) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1660) 01-22 18:31:30.559 11946 11946 E AndroidRuntime: ... 11 more 01-22 18:31:30.559 11946 11946 E AndroidRuntime: Caused by: java.lang.ClassNotFoundException: android.view.Checkbox in loader dalvik.system.PathClassLoader[/data/app/com.example.hi-1.apk] ©2012 Immersion Corporation–Confidential

Toast Toast – an easy way to make text “pop up” on screen. Do it when in UI thread in Activity. ! import android.widget.toast;! …! Toast.makeText( this, ! ! ! !“my string”,! ! ! !Toast.LENGTH_LONG ).show();! ! ! this is the toast pop-up ©2012 Immersion Corporation–Confidential

Some great Android resources §  http://developer.android.com §  http://developer.immersion.com §  http://stackoverflow.com §  Web search for keywords “Android notification tutorial” §  Have a great time with this! ©2012 Immersion Corporation–Confidential

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