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Programming with Android:Introduction

Engr. Julius S. Cansino

Programming with Android:Layouts

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Views: outline

Main difference between a Drawable and a Viewreaction to events

Could be declared in an XML file

Could also be declared inside an Activity

Every view has a unique ID Use findViewById(int id) to get it

Views can be customized

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Some useful methods

getLeft()

getTop() getMeasuredWidth()

getMeasuredHeight()

getWidth() getHeight()

requestLayout()

invalidate()

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ViewGroup and layout

ViewGroup is a view container

It is responsible for placing other views on the

display

Every layout must extend a ViewGroup

Every view needs to specify: android:layout_height

android:layout_width

A dimension or one ofmatch_parent orwrap_conte

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Layouts

Some layouts are pre-defined by Android

Some of these are

LinearLayout

RelativeLayout

TableLayout

FrameLayout

AbsoluteLayout

A layout could be declared inside another layou

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LinearLayout

Dispose views on a single row or column, depen

on android:layout_orientation The orientation could also be declared via

setOrientation(int orientation)

orientation is one ofHORIZONTAL orVERTICAL

Has two other attributes: gravity

weight

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LinearLayout

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LinearLayout

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LinearLayout

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LinearLayout

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LinearLayout weight

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LinearLayout weight

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LinearLayout gravity

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LinearLayout gravity

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LinearLayout problem

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RelativeLayout

Disposes views according to the container or

according to other views The gravity attribute indicates what views are m

important to define the layout

Useful to align views

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RelativeLayout

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RelativeLayout

l i

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RelativeLayout

T bl L

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TableLayout

As the name say, similar to a Table

Has some attributes to customize the layout:

android:layout_column

android:layout_span

android:stretchColumns

android:shrinkColumns

android:collapseColumns

Each row is inside a element

T bl L t

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TableLayout

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TableLayout

T bl L t

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TableLayout

FrameLayout and AbsoluteLayout

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FrameLayout and AbsoluteLayout

FrameLayout

Adds an attribute, android:visibility

Makes the user able to define layouts managing the

visibility of views

AbsoluteLayout

Deprecated

Specify position with x and y

Pay attention to different resolutions

Adapters

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Adapters

Used to visualize data

Make a ViewGroup to interact with data

Some methods:

isEmpty()

getItem(int position)

getCount()

getView()

AdapterView

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AdapterView

A ViewGroup subclass

Its subchilds are determined by an Adapter

Some subclasses:

ListView

GridView

Spinner

Gallery

ListView example

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ListView example

public class HelloAndroidActivity extends Activity {

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.list);

String[] data = {"First", "Second", "Third"};

ListView lv = (ListView)findViewById(R.id.list);

lv.setAdapter(new ArrayAdapter(this, android.R.layout.simple_list_item_1, data));

}

}

ListView

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ListView

Other views/adapters

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Other views/adapters

Spinner, selection of multiple items

Gallery, images

ExpandableListView, list with hidden values

TabWidget, tabbed layouts