The document discusses several Java concepts including packages, access modifiers, encapsulation, getters and setters, and anonymous classes. It provides the following key points: 1. Packages provide a mechanism for grouping related types together in a unique namespace and common conventions for naming packages include using the domain name reversed plus the program name. 2. Access modifiers like private, default, protected, and public control the visibility of declarations. Private is most restrictive while public allows access from anywhere. 3. Encapsulation is the idea that an object should not reveal details it does not intend to support. Getters and setters are a common example of encapsulation in Java. 4. Anonymous classes provide a

1. More Java: Encapsulation, Getters, Setters,
Anonymous Class
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2. Java Packages
 Provide a mechanism for grouping related
types together in a universally unique
namespace.
 java.lang
 Java.util
 How to name a package?
 Domain name reversed
 Ex. domain android.com will be package com.android
 Plus name of the program
 Ex. com.android.notepad
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3. Access Modifiers
 Keywords that modify the visibility of the
declarations to which they are applied
 Private: most restrictive. Not visible outside the
block that contains it.
 Default or package access: next most restrictive.
Visible only from other classes in package.
 Protected: permits all default access rights plus
access from within any subtype.
 Public: allows access from anywhere.
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4. Encapsulation
 The idea that an object should never reveal
details about itself that it does not intend to
support.
 Getters and Setters:
 Common example of encapsulation in Java
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5. Getters and Setters example
 Create a class Contact that extends
Comparable<Contact>:
 Fields: name, age, email
 Create constructor with arguments: name, age,
email
 Create getters and setters for all three fields
 Create method compareTo to sort contacts by e-
mail
 Test
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6. Anonymous Class
 Callback: your code needs to be notified
when something in the UI changes.
 Ex. a button is pushed and we need to change
state, new data has arrived from the network and
it needs to be displayed
 Java provides idiom to pass blocks in code
 Anonymous classes are a handy tool for
expressing many kinds of code blocks.
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7. 7
Without anonymous class With anonymous class
public class myDataModel{
//Callback class
private class keyHandler implements
View.onKeyListener {
public boolean onKey(View v,
int keyCode, KeyEvent event) {
handleKey(v, keyCode,
event);
}
}
/* @param view in the view we model */
public myDataModel(View view){
view.setOnKeyListener(new
KeyHandler())
}
/** Handle a key event **/
void handleKey(View v, int keyCode,
KeyEvent event){
// key handling code goes here …
}
}
public class myDataModel{
/* @param view in the view we model */
public myDataModel(View view) {
view.setOnKeyListener(
// this is an anonymous class!!
new View.OnKeyListener() {
public boolean onKey(View v, int
keyCode, KeyEvent event) {
handleKey(v, keyCode,
event);
}
} );
/** Handle a key event **/
void handleKey(View v, int keyCode,
KeyEvent event){
// key handling code goes here …
}
}
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8. References
 Programming Android by Zigurd Mednieks,
Laird Dornin, G. Blake Meike, Masumi
Nakamura
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9. Install ADT and AVD
 http://developer.android.com/sdk/index.html#d
ownload
 If you already have eclipse use an Existing IDE
option
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10. Install notes
 Don’t forget to configure the ADT (Eclipse,
Window, Preferences, Android)
 Do not forget to set an AVD target (run
configuration)
 Do not forget to assign SD memory
 Check devices: use the proper one
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11. Hello Android!!
 New android project
 Delete activity_main.xml
 Right click layout -> create new xml. Choose
relative layout
 Configure resolution: samsung nexus 4 inch
screen, 480-by-800
 Create AVD
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12. Hello Android!!
 Drawables:
 Hdpi: high density
 Mdpi: medium density
 Ldpi: low density
 Xhdpi: extra high
 Change ID property for relative layout
 +: create new variable with name
 Change BG property
 RGB color map
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13. Hello Android!!
 Add a TextView
 Configure text property: create a new string
resource (good practice)
 R.String: name
 String: content
 Configure text size:
 Dp: density independent pixel
 Configure layout margin top
 Text color: #00F
 Text Style: bold
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14. Hello Android!!
 Add image view
 Create new drawable: be careful with names! No
hyphens allowed
 Change:
 Id
 Layout below: put it under your textview
 Layout center horizontal
 Src: do not forget to add your image in a drawable
directory
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