Mobile Software Engineering Crash Course - C04 Android Cont

Mohammad Shaker

FIT of Damascus - AI dept.

MohammadShakerGtr@gmail.com

Mobile SE – August 2012

Mobile

Software

Engineering

L04 – Android Cont.

ActivitiesStarting Another Activity

Intentan object that provides runtime binding between separate

components (such as two activities)

Intentcarry a collection of various data types as key-value pairs

called extras through putExtra()

It’s a good practice..to define keys for intent extras using your app's package name as a prefix.

This ensures they are unique, in case your app interacts with other apps.

Starting Another Activityhttp://developer.android.com/training/basics/firstapp/starting-activity.html#BuildIntent

Project Attached

Starting Another Activity

public final static String EXTRA_MESSAGE = "com.example.intetsample.MESSAGE";

public void sendMessage(View view) {

Intent intent = new Intent(this, DisplayMessageActivity.class);

EditText editText = (EditText) findViewById(R.id.editText1);

String message = editText.getText().toString();

intent.putExtra(EXTRA_MESSAGE, message);

startActivity(intent);

}

AndroidManifest.xml

AndroidManifest.xml<application

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name=".MainActivity"

android:label="@string/title_activity_main" >

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

<activity

android:name=".DisplayMessageActivity"

android:label="@string/title_activity_display_message" >

<meta-data

android:name="android.support.PARENT_ACTIVITY"

android:value="com.example.intetsample.MainActivity" />

</activity>

</application>

Managing the Activity

Life Cycle

Destroy the activityonDestroy()

Destroy the activity

onPasue()

@Override

public void onPause() {

// Always call the superclass method first

super.onPause();

// Release the Camera because

// we don't need it when paused

// and other activities might need to use it.

if (mCamera != null) {

mCamera.release()

mCamera = null;

}

}

onResume()

@Override

public void onResume() {

// Always call the superclass method first

super.onResume();

// Get the Camera instance as the activity

// achieves full user focus

if (mCamera == null) {

// Local method to handle camera init

initializeCamera(); }

}

Recreating activityonSaveInstanceState

Storage – DatabaseSqlite3

Draggable stick project sample attached

OpenGL ES

How can we animate?

'Must Override a Superclass

Method' Errors after importing a

project into Eclipse Problemhttp://stackoverflow.com/questions/1678122/must-override-a-superclass-

method-errors-after-importing-a-project-into-eclips

@Override

public boolean onTouchEvent(MotionEvent e) {

float x = e.getX(); float y = e.getY();

switch (e.getAction()) {

case MotionEvent.ACTION_MOVE:

float dx = x - mPreviousX; float dy = y - mPreviousY;

// reverse direction of rotation above the mid-line

if (y > getHeight() / 2) { dx = dx * -1 ; }

// reverse direction of rotation to left of the mid-line

if (x < getWidth() / 2) { dy = dy * -1 ; }

mRenderer.mAngle += (dx + dy) * TOUCH_SCALE_FACTOR;

// = 180.0f / 320

requestRender();

}

mPreviousX = x; mPreviousY = y;

return true;

}

Let’s get our hands dirty

with code!

Advanced Training• Making Your App Location Aware• Performing Network Operations• Transferring Data Without Draining the Battery• Syncing to the Cloud• Designing for Multiple Screens• Improving Layout Performance• Managing Audio Playback• Optimizing Battery Life• Creating Custom Views• Adding Search Functionality

• Remembering Users• Sharing Content• Capturing Photos• Maintaining Multiple APKs• Creating Backward-Compatible UIs• Developing for Enterprise• Monetizing Your App

• Designing Effective Navigation• Implementing Effective Navigation• Designing for TV• Displaying Bitmaps Efficiently• Implementing Accessibility• Displaying Graphics with OpenGL ES

See you nxt time!