Build An Application Launcher For Android | Taywils.me

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Build AnBuild AnApplicationApplicationLauncher ForLauncher ForAndroidAndroid

To start off create a new

Android application

project within Eclipse.

Whenever I develop

Android apps I usually

start with the layout of the

application and add

functionality via Java

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classes later. Since our app

will display the users

installed apps within a

ListView widget we have

to first declare a layout to

hold the ListView itself.

Create a new xml layout

for the ListView by right

clicking the res/layout

folder and adding a new

android xml file. Title it

"applauncher.xml" and

then add the code below to

it.

<LinearLayout

xmlns:android="http://schemas.android.com/apk/res/android"

android:id="@+id/applauncher_linearlayout"

android:layout_width

android:layout_height

android:orientation

<ListView

android:id=



<TextView

android:id=



android:text



When using ListViews we

can setup the overall look

of each row by creating an

xml layout with a skeleton

of the widgets that we

want to display in each row

of our ListView. Think of

the row layout as a "row

template". If you look at

the screenshots of the app

you can tell that we only

need two widgets within

our row layout, an

ImageView to hold the

apps icon and a TextView

to display the apps

package name. Create a

new xml layout for the

ListView rows by right

clicking the res/layout

folder and adding a new

android xml file. Title it

"applauncherrow.xml" and

add the code below.

</LinearLayout>



Next we're going to setup

the main activity for the

launcher app and register

the activity in the manifest.

Create a new Java Class

<LinearLayout


android:id="@+id/applauncherrow_imagelinearlayout"



android:padding="6dip"

<ImageView

android:id="@+id/applauncherrow_icon"



android:layout_marginRight

<LinearLayout

android:id="@+id/applauncherrow_namelinearlayout"

android:orientation


android:layout_weight


<TextView

android:id="@+id/applauncherrow_appname"



android:layout_weight

android:gravity

</LinearLayout>

</LinearLayout>

and name it

"AppLauncher.java". Next

open up the manifest file

for your application and

make sure it looks like the

code below.



<manifest


package="org.example.hello"

android:versionCode

android:versionName



<application

android:icon="@drawable/icon"

android:label

android:debuggable

android:description

<activity

android:name

android:label



<intent-filter>

<action

<category

</intent-filter>

</activity>

</application>

<uses-sdk android:minSdkVersion



Ok so now that the layouts

are coded up and the

activity is registered within

the manifest open up

AppLauncher.java and lets

begin. Lets start off with

importing all the necessary

libraries needed for our

app.

</manifest>

//Your package name might differ

package org.example.hello;

import java.util.ArrayList;

import java.util.Collections

import java.util.List;

import android.app.ListActivity

import android.app.ProgressDialog

import android.content.ComponentName

import android.content.Context

import android.content.Intent

import android.content.pm.ActivityInfo

import android.content.pm.PackageInfo

import android.content.pm.PackageManager

import android.content.pm.ResolveInfo

import android.graphics.drawable

import android.os.Bundle;

import android.util.Log;

import android.view.LayoutInflater

import android.view.View;



Our app will extend the

ListActivity class in order

to reduce the boiler plate

needed to build a ListView.

However, due to the

structure of the app we'll

build the classes needed

and stitch them together

so just follow along with a

text editor for now. To

begin we'll need a class to

hold all the useful data we

can obtain from a given

app. We'll call it AppInfo,

its very basic so go ahead

and type it into your editor.

import android.view.ViewGroup

import android.widget.ArrayAdapter

import android.widget.ImageView

import android.widget.ListView

import android.widget.TextView

public class AppLauncher extends

public class AppInfo{

private String

private String

private String

private String



The next class we need is a

class that will be used to

obtain the application info

for the AppInfo class. This

class is the bread and

butter of our AppLauncher

and it together with the

private Integer

private Drawable

public String

return

}

public String

return

}

public String

return

}

public String

return

}

public Integer

return

}

public Drawable

return

}

}



AppInfo class can be

ported to any application

which needs to access

other apps via intents.

For the Applications

constructor we will pass in

the all important

PackageManager from the

main context.

Below are some getter

methods for the package

and activities list. The

difference between the

two is that the package list

contains the info about the

apps data and the activity

public class Applications{

private ArrayList

private List

private Intent

private PackageManager

public Applications(PackageManager

packMan

packageList

activityList

this

}



list contains info about the

intents the app responds

to.

The next method is the

createPackageList method.

All it does is simply extract

a list of all the installed

apps via the

PackageManager that we

passed into the

constructor. Next we

iterate over the list and

copy the info we need into

a AppInfo object and then

shove that object into the

ArrayList<AppInfo> that

will be returned.

public ArrayList getPackageList

return

}

public List

return

}

private ArrayList createPackageList

ArrayList

List packs



Similar to the

createPakageList method,

createActivityList will

return a list with all of the

apps installed intent data

but unlike

createPackageList its only

8 lines of code.

for(int

PackageInfo

if((!

}

AppInfo

newInfo

getPackageManager

newInfo

newInfo

newInfo

newInfo

getPackageManager

pList

}

return pList

}

private List createActivityList

List



The next two methods are

purely for dubugging

purposes and can actually

be left out but we'll include

them for completeness or

in case you use this class in

another application.

Collections

return

}

private void packageDebug(){

if(

}

for

packageList

packageList

packageList

packageList

packageList

}

}

private void

if(

}



The next method is needed

only because in order to

launch an app you need

both its package name and

its intent name that

connects to the main class

of the app. However, if you

only use the packageList

you'll lack the intent data,

so the last method of the

Application class adds the

class name(intent data) to

the packageList making it

such that client of the class

can have everything

bundled up nicely in the

packageList instead of

having to rely on using

both the activity and

for

i

}

}



packageList in unison. For

the method

addClassNameToPackageList

we'll iterate over the

packageList and for each

packageName we'll find its

match within the

activityList by

packageName and then

extract the className

from the activityList.

private void addClassNamesToPackageList

if(null

}

String

for(int

tempName

j

packageList

j

}

}

}



Below is the complete

Application class


private ArrayList

private List

private Intent


public Applications

packMan

packageList

activityList

this

}

public ArrayList

return

}

public List

return

}

private ArrayList

ArrayList

List packs

for(int

PackageInfo

if((!

}

AppInfo



newInfo

getPackageManager

newInfo

newInfo

newInfo

newInfo

getPackageManager

pList

}

return pList

}

private List

List

Collections

return

}

private void

if(

}

for

packageList

packageList

packageList

packageList

packageList

}

}



Remember the AppInfo

class that we made and the

private void

if(

}

for

i

}

}

private void

if(

}

String

for

tempName

j

packageList

j

}

}

}



applauncherrow.xml

layout. Well, now we'll

utilize both within the

custom ArrayAdapter

extension we'll use to

populate the data of our

List. ArrayAdapters are

used to fill in the data fields

of a ListView widget by

storing a layout(android

uses the term inflate)

holding data into a single

row of the list.

The constructor for our

ArrayAdapter extension...

Being an ArrayAdapter

extension means that we

have to override the

getView method, this is

public class ApplicationAdapter

private ArrayList

public ApplicationAdapter(Context

super(context, textViewResourceId

this.items = items;

}



where the applauncherrow

layout is populated with

data and is used to

represent each row of the

ListView. To start we'll

reference the

applauncherrow layout

and inflate it to become a

view.

Now that the view is

inflated with the

applauncherrow.xml

layout we can now match

the ImageView and

TextView with the

contents of a AppInfo

object in preparation for

moving it into the ListView.

@Override

public View getView

ViewGroup

View

if(

view

}



Here is the complete

ApplicationAdapter class,

you should add it to your

text file.

AppInfo appInfo = items.get

if(

R

R

appName

appIcon

}

return

}

}


private ArrayList

public ApplicationAdapter


this.items = items

}

@Override

public View getView

ViewGroup



We are done with the

utility classes so the next

step is to add some

methods to the

AppLauncher class itself.

The first one we're going

to add is a method called

getApps() which stores the

View

if(

view

}

AppInfo

if(

R

R

appName

appIcon

}

return

}

}



pacakageList from an

Applications object and

passes it off to Java

Runnable to be ran on a

thread.

If you look at the getApps()

method the last line before

the class ends is a method

called

this.runOnUiThread(returnRes),

now what this means is

that the main thread will

be locked while we pump

AppInfo objects into our

ListView via the

ArrayAdapter. If you are

experienced with

concurrent programming

private void getApps(){

try{

myApps

packageList

}

catch(Exception

Log

}

this.runOnUiThread

}



you might be wondering

why lock the

mainUIThread, the answer

is because our app can't do

anything until all objects

have been added to the

list. If we by chance were

dynamically loading things

from the Internet via

HTTP requests then we

would opt instead for a

lazy loader which spawns a

thread for each view

object pumped into the

ListVIew and the list would

slowly populate as each

item was fetched live from

the web. So anyways here

is our Runnable method

that checks first that the

packageList exists and

then uses an object from

our ApplicationAdapter to

fill up our ListView widget.

private Runnable returnRes

public void

if(



We're almost done so now

open up your Eclipse IDE

to the AppLauncher

project and click on the

AppLauncher.java class. If

you remember from earlier

where we left off go ahead

and add the data members

below to the AppLauncher

class; notice the line

numbers for reference.

For the onCreate() method

there are some things you

sould notice. First since

appAdapter

appAdapter

}

progressDialog

appAdapter

}

};

ApplicationAdapter appAdapter

ProgressDialog progressDialog

Runnable viewApps =

ArrayList packageList

Applications myApps



AppLauncher is a

ListActivity extension it

inherits the

setListAdapter() method.

Second we'll initialize the

viewApps Runnable to call

our getApps() within its

run(). This means that any

thread created with the

viewApps as it's runnable

will load up our packages

into the ListView. In

addition since getApps()

locks the mainUIThread

users of this app won't be

able to do anything until

the thread finishes.

public void onCreate(Bundle

super.onCreate

this.setContentView

packageList

appAdapter

packageList

this.setListAdapter

viewApps =

public



Now that the thread has

started and the app has

been officially locked, how

do we notify the user? The

answer is with the

android.app.ProgressDialog

widget. Remember those

loading screen from

popular video games,

that's all ProgressDialogs

do.

Right now our app can

successfully load up a list

of Icons and application

names but how then do we

launch the apps the user

touches from our list? The

answer is via starting a

getApps

}

};

Thread appLoaderThread

appLoaderThread

progressDialog = ProgressDialog

}



new intent by overriding

the onListItemClick

method. So go open up

your text file that contains

the utility classes and

methods and add the

onListItemClick() method

to it.

Before you run the

AppLauncher, be sure to

copy and paste the classes

and methods into the

AppLauncher class so it

@Override

protected void onListItemClick

long

super.onListItemClick

AppInfo rowClicked

position

Intent startApp

ComponentName

rowClicked

rowClicked

startApp.setComponent

startApp.setAction

startActivity

}



resembles the complete

file below.

org.example.hello;

java.util.ArrayList;

java.util.Collections;

java.util.List;

android.app.ListActivity;

android.app.ProgressDialog;

android.content.ComponentName

android.content.Context;

android.content.Intent;

android.content.pm.ActivityInfo

android.content.pm.PackageInfo

android.content.pm.PackageManager

android.content.pm.ResolveInfo

android.graphics.drawable.Drawable

android.os.Bundle;

android.util.Log;

android.view.LayoutInflater;

android.view.View;

android.view.ViewGroup;

android.widget.ArrayAdapter;

android.widget.ImageView;

android.widget.ListView;

android.widget.TextView;

class AppLauncher extends ListActivity

ApplicationAdapter appAdapter

ProgressDialog progressDialog

Runnable viewApps = null;

ArrayList packageList = null

Applications myApps = null;

public void onCreate(Bundle savedInstanceState

super.onCreate(savedInstanceState



this.setContentView(

packageList = new ArrayList

appAdapter = new ApplicationAdapter

packageList

this.setListAdapter(

viewApps = new Runnable

public void run

getApps

}

};

Thread appLoaderThread

"AppLoaderThread"

appLoaderThread.start

progressDialog = ProgressDialog

"Hold on..."

}


private ArrayList packageList

private List activityList

private Intent mainIntent


public Applications(

packMan = packManager

packageList

activityList

this.addClassNamesToPackageList

}

public ArrayList getPackageList

return packageList



}

public List getActivityList

return activityList

}

private ArrayList createPackageList

ArrayList pList

List packs = getPackageManager

).getInstalledPackages

for(int i = 0; i

PackageInfo packInfo

if((!getSysPackages

continue

}

AppInfo newInfo

newInfo.appName

getPackageManager

newInfo.packageName

newInfo.versionName

newInfo.versionCode

newInfo.icon

getPackageManager

pList.add(newInfo

}

return pList;

}

private List createActivityList

List aList =

Collections.



return aList

}

private void packageDebug

if(null == packageList

return

}

for(int i =

Log.

packageList

packageList

packageList

packageList

packageList

}

}

private void activityDebug

if(null == activityList

return

}

for(int i =

ActivityInfo

i

Log.

}

}

private void addClassNamesToPackageList

if(null == activityList

return



}

String tempName

for(int i =

tempName

for(

j

packageList

j

}

}

}

}

public class AppInfo{

private String appName

private String packageName

private String className

private String versionName

private Integer versionCode

private Drawable icon

public String getAppName

return appName

}

public String getPackageName

return packageName

}

public String getClassName

return className

}



public String getVersionName

return versionName

}

public Integer getVersionCode

return versionCode

}

public Drawable getIcon

return icon;

}

}


private ArrayList items

public ApplicationAdapter

ArrayList


this.items = items;

}

@Override

public View getView(int position

ViewGroup parent

View view = convertView

if(view == null

LayoutInflater

view

}

AppInfo appInfo

if(appInfo !=

TextView

R

ImageView



R

if(appName

appName

}

if(appIcon

appIcon

}

}

return view;

}

}

private void getApps(){

try{

myApps = new

packageList

}

catch(Exception exception

Log.e("BACKGROUND PROC:"

}

this.runOnUiThread(returnRes

}

private Runnable returnRes =

public void run(){

if(packageList

appAdapter

for(

appAdapter

}

}

progressDialog

appAdapter.notifyDataSetChanged

}

};



Enjoy your AppLauncher.

@Override

protected void onListItemClick

long id){

super.onListItemClick

AppInfo rowClicked =

position

Intent startApp = new

ComponentName component

rowClicked

rowClicked

startApp.setComponent

startApp.setAction(Intent

startActivity(startApp

}



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• Reply •

felipetio • 6 months ago

Have a project source? Thx 13

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Paul Marcellana• 3 months ago

May you please provide aproject source. I need itbadly. Thanks

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• Reply •

Sagara S.Dev• 2 months ago

for PackageInfo packInfo =packs.get(i); i am gettingType Mismatch: can notconvert from object toPackage info error. anysuggetions?

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