Android intents-3 www.j2program.blogspot.com

© 2012 Marty Hall

Intents, Intent Filters,
and Invoking Activities:
Part III: Using Tabs
Originals of Slides and Source Code for Examples:
http://www.coreservlets.com/android-tutorial/
Customized Java EE Training: http://courses.coreservlets.com/
Java, JSF 2, PrimeFaces, Servlets, JSP, Ajax, jQuery, Spring, Hibernate, RESTful Web Services, Hadoop, Android.

Developed and taught by well-known author and developer. At public venues or onsite at your location.

© 2012 Marty Hall

For live Android training, please see courses
at http://courses.coreservlets.com/.
Taught by the author of Core Servlets and JSP, More
Servlets and JSP, and this Android tutorial. Available at
public venues, or customized versions can be held
on-site at your organization.
• Courses developed and taught by Marty Hall
– JSF 2, PrimeFaces, servlets/JSP, Ajax, jQuery, Android development, Java 6 or 7 programming, custom mix of topics
– Ajax courses can concentrate on 1EE Training: http://courses.coreservlets.com/several
Customized Java library (jQuery, Prototype/Scriptaculous, Ext-JS, Dojo, etc.) or survey

• Courses developed and taught by coreservlets.com experts (edited by Marty)

Java, JSF 2, PrimeFaces, Servlets, JSP, Ajax, jQuery, Spring,and RESTful Web Services Services, Hadoop, Android.
Hibernate, RESTful Web
– Spring, Hibernate/JPA, EJB3, GWT, Hadoop, SOAP-based
Contact hall@coreservlets.com for details

Topics in This Section
• Part I
– Invoking Activities by class name
– Defining dimensions in res/values
– Sending data via the “extras” Bundle

• Part II
– Invoking Activities with a URI
– Sending data via parameters in the URI

• Part III
– Invoking Activities with tabbed windows
– Defining two-image icons in res/drawable

5

© 2012 Marty Hall

Overview



Summary of Options
• Invoke Activity by class name (Part I)
– Exactly one Activity can match
– New Activity must be in same project as original
– Can send data via an “extras” Bundle

• Invoke Activity by URI (Part II)
– More than one Activity could match
– New Activity need not be in the same project as original
– Can send data via URI parameters or “extras” Bundle

• Switch Activities via tabs (Part III)
– Can use class name or URI to specify Activity
– New Activity must be in same project as original
– Can send data via URI parameters or “extras” Bundle
7

© 2012 Marty Hall

Invoking Activities with
Tabbed Windows


Summary
• Idea
– Make tabbed windows. Each tab invokes a different Activity,
or an Activity with different data.
• Can use either specific-class approach or URI approach
• Can send data either with an extras Bundle or in URI
• Tab window Activity and new Activities must be in same project
– Due to security reasons

• Syntax
– Java
• Extends TabActivity. Uses TabHost and TabSpec
– Details on next slide

– XML (AndroidManifest.xml)
• Same as shown earlier
9

Using TabActivity: Outline
public class SomeActivity extends TabActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Resources resources = getResources();
TabHost host = getTabHost();
Intent intent1= ...;
Drawable tabIcon =
resources.getDrawable(R.drawable.icon_name);
TabSpec tab1Spec =
host.newTabSpec("Tab One")
.setIndicator("Some Text", tabIcon)
.setContent(intent1);
host.addTab(tab1Spec);
// Repeat for other tabs
}
Note that the setter methods for TabSpec return the TabSpec so that you can do chained assignments.
}
Note also that there is no layout file when using this approach.
10

Defining Tab Icons
• Idea
– Although it is legal to call setIndicator(someString), the
resultant tab looks bad because of blank space at top. So,
more common to do setIndicator(someString, someIcon).
• You can also do setIndicator(someView) for fancy tabs

• Icon option 1
– Use a single image for the icon
• Same image used when the tab is or is not selected

• Icon option 2
– Use 2 similar but differently colored images for the icon
• One for when selected, one for when not

11

Option 1: A Single Image
• Pros
– Simpler
– Text color and background color of the tab already
change on selection, so not confusing if icon stays same.

• Cons
– Doesn’t look quite as good as with two images

• Approach
– Put image file in res/drawable/some_icon.png
– Refer to image with
• Drawable tabIcon =
resources.getDrawable(R.drawable.some_icon);

– Put icon in tab label with
12

• tabSpec.setIndicator("Some Text", tabIcon);

Option 2: Two Images
(Normal and Selected)
• Pros
– Looks better

• Cons
– More work

• Approach
– Put image files in
• res/drawable/some_icon_normal.png
and
• res/drawable/some_icon_selected.png

– Make XML file (next page)
• res/drawable/some_icon.xml

– Refer to XML file with
• Drawable tabIcon =
resources.getDrawable(R.drawable.some_icon);

– Put icon in tab label with
• tabSpec.setIndicator("Some Text", tabIcon);
13

XML Code for Dual-Image Icon
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://...">

<item android:drawable="@drawable/some_icon_selected"
android:state_selected="true" />

<item android:drawable="@drawable/some_icon_normal" />
</selector>

The file names of the two images are arbitrary. They need not end in _selected and _normal, although
this can be a useful convention so that you know what the images are for.
14

© 2012 Marty Hall

Example:
Invoking Loan Calculator
(Each Tab Sends
Different Data)


Example: Overview
• Initial Activity
– Has tabs that, when pressed, invoke the
loan calculator with different data
• Activity specified either with class name or URI
– But either way, initial Activity must be in same project as new one

• Data sent via either in extras Bundle or in URI

• Approach
– Intents and data created in same way as before
– Intent associated with tab via tabHost.setContent
– Put entry for LoanCalculatorActivity in manifest
• Same as shown previously

16

XML: Icon File
(res/drawable/calculator.xml)
<selector xmlns:android="http://schemas.android.com/apk/res/android">


<item android:drawable="@drawable/calculator_white"

<item android:drawable="@drawable/calculator_black" />
</selector>

17

XML: Manifest File
Action Declaration
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.coreservlets.intentfilter1"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="8" />
<application android:icon="@drawable/icon"
android:label="@string/app_name">
... 
<activity android:name=".LoanCalculatorActivity"
android:label="@string/loan_calculator_app_name">
<intent-filter>
<action android:name="android.intent.action.VIEW" />
<category android:name="android.intent.category.DEFAULT" />
<data android:scheme="loan" android:host="coreservlets.com" />
</intent-filter>
</activity>
...
</application>
Unchanged from previous examples.
</manifest>

18

Java
(TabbedActivity: Tab 1)
public class TabbedActivity extends TabActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Resources resources = getResources();
Intent intent1 =
new Intent(this, LoanCalculatorActivity.class);
Bundle loanBundle1 =
LoanBundler.makeLoanInfoBundle(100000, 7.5, 120);
intent1.putExtras(loanBundle1);
Drawable tabIcon =
resources.getDrawable(R.drawable.calculator);
TabSpec tab1Spec = host.newTabSpec("Tab One")
.setIndicator("10 Year", tabIcon)

19

This first tab uses an Intent that specifies the Activity by class name.
It sends data via an extras Bundle. Reminder: there is no layout file when using TabActivity.

Java
Uri uriTwentyYear =
Uri.parse("loan://coreservlets.com/calc");
Intent intent2 =
new Intent(Intent.ACTION_VIEW, uriTwentyYear);
Bundle loanBundle2 =
LoanBundler.makeLoanInfoBundle(100000, 7.5, 240);
intent2.putExtras(loanBundle2);
tabIcon = resources.getDrawable(R.drawable.calculator);
TabSpec tab2Spec = host.newTabSpec("Tab Two")

20

This second tab uses an Intent that specifies the Activity with a URI.
It sends data via an extras Bundle.

Java
String baseAddress = "loan://coreservlets.com/calc";
String address =
String.format("%s?%s&%s&%s",
baseAddress,
"loanAmount=100000",
"annualInterestRateInPercent=7.5",
"loanPeriodInMonths=360");
Uri uriThirtyYear = Uri.parse(address);
Intent intent3 =
new Intent(Intent.ACTION_VIEW, uriThirtyYear);
tabIcon = resources.getDrawable(R.drawable.calculator);
TabSpec tab3Spec = host.newTabSpec("Tab Three")

21

This second tab uses an Intent that specifies the Activity with a URI.
It sends data via parameters embedded in the URI.

Example: Results

22

© 2012 Marty Hall

Wrap-Up


Summary
• Java (extends TabActivity)
Intent intent1= ...; // Refers to Activity in same project
Drawable tabIcon = resources.getDrawable(R.drawable.some_icon);
TabSpec tab1Spec = host.newTabSpec("Tab One")
.setIndicator("Some Text", tabIcon)
// Repeat for other tabs

• Icon (res/drawable/some_icon.xml)

24

<selector xmlns:android="http://...">
<item android:drawable="@drawable/some_icon_selected"
<item android:drawable="@drawable/some_icon_normal" />
</selector>

© 2012 Marty Hall

Questions?
JSF 2, PrimeFaces, Java 7, Ajax, jQuery, Hadoop, RESTful Web Services, Android, Spring, Hibernate, Servlets, JSP, GWT, and other Java EE training.



Android intents-3 www.j2program.blogspot.com

Recommended

More Related Content

What's hot (20)

Viewers also liked (7)

Similar to Android intents-3 www.j2program.blogspot.com (20)

Recently uploaded (20)

Android intents-3 www.j2program.blogspot.com