Android Coding. Dr. J.P.E. Hodgson. August 23, Dr. J.P.E. Hodgson () Android Coding August 23, / 27

Transcription

1 Android Coding Dr. J.P.E. Hodgson August 23, 2010 Dr. J.P.E. Hodgson () Android Coding August 23, / 27

2 Outline Starting a Project 1 Starting a Project 2 Making Buttons Dr. J.P.E. Hodgson () Android Coding August 23, / 27

3 Starting a Project A New Project 1 File -> New -> Android Project 2 Then select/enter: Project name: Choose the name Build Target: Android 2.2 Application name: Chhose ag0ain Package name: edu.sju.projectname Create Activity: Name Min SDK Version: 8 Dr. J.P.E. Hodgson () Android Coding August 23, / 27

4 Starting a Project Using existing Project Code 1 File -> New -> Android Project 2 Select Create project from Existing Source 3 Browse to the code. All the Demo code is zipped together on the code page of the web. 4 Start the Android emulator before you do anything else! (Fast it ain t!) Dr. J.P.E. Hodgson () Android Coding August 23, / 27

5 Outline 1 Starting a Project 2 Making Buttons Dr. J.P.E. Hodgson () Android Coding August 23, / 27

6 Making Buttons JPEH Demo This version produces a initial menu. About Exit Both of these are functional. Dr. J.P.E. Hodgson () Android Coding August 23, / 27

7 Making Buttons Background Color and Menu JPEHDemo/values/colors.xml JPEHDemo/res/layout/main.xml If you just use this you get the menu but nothing else. Dr. J.P.E. Hodgson () Android Coding August 23, / 27

8 Implementing the About box Three choices 1 Define a New Activity and start it; 2 Use the AlertDialog class, and show it; 3 Subclass Android s Dialog Class, and show that. Dr. J.P.E. Hodgson () Android Coding August 23, / 27

9 Layout file for the activity JPEHDemo/res/layout/about.xml Works equally well in landscape mode. Add to JPEHDemo/res/values/strings.xml Dr. J.P.E. Hodgson () Android Coding August 23, / 27

10 strings.xml addition for about box <?xml version="1.0" encoding="utf-8"?> <resources> <string name="main_title">jpeh Android Demo</string> <string name="app_name">jpehdemo</string> <string name="about_label">about</string> <string name="exit_label">exit</string> <string name="about_title"> About JPEH Android Demo</strin <string name="about_text">\ This is a simple App to Demonstrate some of the code required to create Android Apps. </string> </resources> Dr. J.P.E. Hodgson () Android Coding August 23, / 27

11 The About activity 1 File -> New -> Class 2 JPEHDemo/src/edu/sju/JPEHDemo/About.java 3 You need to say that it extends android.app.activity there is an box for this. Dr. J.P.E. Hodgson () Android Coding August 23, / 27

12 package edu.sju.jpehdemo; import android.app.activity; import android.os.bundle; public class About extends Activity protected void oncreate(bundle savedinstancestate){ super.oncreate(savedinstancestate); setcontentview(r.layout.about); } } Dr. J.P.E. Hodgson () Android Coding August 23, / 27

13 Wiring this into the Main App: JPEHDemo.java The Import statements import android.app.activity; import android.app.alertdialog; import android.content.dialoginterface; import android.content.intent; import android.os.bundle; import android.util.log; import android.view.view; import android.view.view.onclicklistener; Dr. J.P.E. Hodgson () Android Coding August 23, / 27

14 oncreate public class JPEHDemo extends Activity implements OnClickListe /** Called when the activity is first created. public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.main); View aboutbutton = findviewbyid(r.id.about_button); aboutbutton.setonclicklistener(this); View exitbutton = findviewbyid(r.id.exit_button); exitbutton.setonclicklistener(this); } Dr. J.P.E. Hodgson () Android Coding August 23, / 27

15 The app needs to be an OnClickListener public void onclick(view v){ switch(v.getid()) { case R.id.about_button: Intent i = new Intent(this, About.class); startactivity(i); break; case R.id.exit_button: finish(); break; } } Dr. J.P.E. Hodgson () Android Coding August 23, / 27

16 Add the activity to the manifest Very Important!! <activity android:name=".about" </activity> Dr. J.P.E. Hodgson () Android Coding August 23, / 27

17 Getting the menu at the bottom of the screen The file menu.xml <?xml version="1.0" encoding="utf-8"?> <menu xmlns:android=" <item /> </menu> Dr. J.P.E. Hodgson () Android Coding August 23, / 27

18 strings.xml <string name="settings_label"> Settings...</string> <string name="settings_title"> JPEH Demo Settings</string> <string name="sound_title">sounds</string> <string name="sound_summary">play Action Sounds</string> <string name="color_title">colors</string> <string name="color_summary">choose Colors</string> Dr. J.P.E. Hodgson () Android Coding August 23, / 27

19 In public boolean onoptionsitemselected(menuitem item){ switch(item.getitemid()) { case R.id.settings: startactivity(new Intent(this, Prefs.class)); return true; } return false; } Dr. J.P.E. Hodgson () Android Coding August 23, / 27

20 The Prefs class package edu.sju.jpehdemo; import android.os.bundle; import android.preference.preferenceactivity; public class Prefs extends PreferenceActivity protected void oncreate(bundle savedinstancestate){ super.oncreate(savedinstancestate); addpreferencesfromresource(r.xml.settings); } } Dr. J.P.E. Hodgson () Android Coding August 23, / 27

21 Add to the Manifest <activity android:name=".prefs" </activity> Dr. J.P.E. Hodgson () Android Coding August 23, / 27

22 A pop up menu 1 Add the button to the layout; 2 Add to the strings the items 3 Create the array of item values (next slide) Dr. J.P.E. Hodgson () Android Coding August 23, / 27

23 arrays.xml <?xml version="1.0" encoding="utf-8"?> <resources> <array name="item_choices"> </array> </resources> Dr. J.P.E. Hodgson () Android Coding August 23, / 27

24 Make sure that the view of the button is linked into the Main program. // For each button do the next two lines View itemsbutton = findviewbyid(r.id.jpeh_button); itemsbutton.setonclicklistener(this); Dr. J.P.E. Hodgson () Android Coding August 23, / 27

25 Tell the clicklistener what to do switch(v.getid()) { case R.id.jpeh_button: Log.d(TAG, "Button clicked"); openitemdialog(); break; Dr. J.P.E. Hodgson () Android Coding August 23, / 27

26 The Dialog private void openitemdialog(){ new AlertDialog.Builder(this).setTitle(R.string.item_dialog_title).setItems(R.array.item_choices, new DialogInterface.OnClickListener() { public void onclick(dialoginterface dialog, int which) { doit(which);}).show(); } Dr. J.P.E. Hodgson () Android Coding August 23, / 27

27 Debugging 1 Add to the manifest <application android:icon="@drawable/icon" android:label=" android:debuggable="true"> 2 Use Log.d() for debugging Log.d(TAG, "clicked on " + i); Dr. J.P.E. Hodgson () Android Coding August 23, / 27