Create Application Launcher as a list

This is how Google Android default Application screen looks like:

Default Android Application Launcher

It’s a grid view and when you click on one of those, the corresponding activity is launched.

Ok, so now I’ll guide you how to create a similar one but in a list view. Here the screenshot:

Application Viewer

A – What Does It Do?

- All the installed application on the machine is displayed with their icons, label names and package names.

- When an item is clicked the corresponding activity is launched.

- If the item does not exist, a small message notification will display. (it might not happen, lol)

- If the item exist, but current user does not have the permission to launch, well, just do nothing. (it’s kinda fun on slow emulator )

B – Create the Project

Project Name: Application Viewer

Build Target: Android 2.3.3 (the latest one at this time, well, I like it though)

Application Name: Application Viewer

Package Name: pete.android.study

Create Activity: MainActivity

Min SDK: 10

C – Sketch the Layout

Like old times (my previous post), we need two layouts:

+ one layout for each item in the list view

+ one layout for main list view display

1. List Item Layout (/res/layout/layout_appinfo.xml)

- You may want to refer to my previous tutorial on creating a PhoneBook, because the layout is much alike. I’m feeling lazy to describe it again…zzz

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="?android:attr/listPreferredItemHeight"
  android:padding="5dip"  
  >
  
  <ImageView
      android:id="@+id/ivIcon"
      android:layout_width="wrap_content"
      android:layout_height="fill_parent"
      android:layout_marginRight="5dip"
      android:scaleType="center"
  />
  
  <LinearLayout
      android:orientation="vertical"
      android:layout_width="0dip"
      android:layout_height="fill_parent" 
      android:layout_weight="1"     
  >
  
      <TextView
          android:id="@+id/tvName"
          android:layout_width="fill_parent"
          android:layout_height="0dip"
          android:layout_weight="1"
          android:gravity="center_vertical"          
      />
      
      <TextView
          android:id="@+id/tvPack"
          android:layout_width="fill_parent"
          android:layout_height="0dip"
          android:layout_weight="1"
          android:singleLine="true"
          android:ellipsize="marquee"          
      />
  
  </LinearLayout>
  
  
</LinearLayout>

2. Main Layout (/res/layout/layout_main.xml)

- Just one single list view to apply.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >

	<ListView
		android:id="@+id/lvApps"
		android:layout_width="fill_parent"
		android:layout_height="wrap_content"		
	/>

</LinearLayout>

D – Class Design: On the Idea

This is a quite complicated shit of class diagram. I’m just thinking of making it more details.

Application Viewer - Class Diagram

MainActivity: the entry of the program, we will load list view here, create and set adapter to list view, and handle OnItemClickListener (which is from AdapterView) in list view.

AppInfoAdapter: the adapter inherits from BaseAdapter to handle list item, we need to handle things in getView() (loading controls from resources, set them appropriate values,  get application info meta data..).

Utilities: to support

+ get installed application list.

+ launch an activity.

E – From Design to Coding (w/ Passion)

1. AppInfoAdapter: (AppInfoAdapter.java)

package pete.android.study;

import java.util.List;

import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class AppInfoAdapter extends BaseAdapter {
	private Context mContext;
	private List mListAppInfo;
	private PackageManager mPackManager;

	public AppInfoAdapter(Context c, List list, PackageManager pm) {
		mContext = c;
		mListAppInfo = list;
		mPackManager = pm;
	}

	@Override
	public int getCount() {
		return mListAppInfo.size();
	}

	@Override
	public Object getItem(int position) {
		return mListAppInfo.get(position);
	}

	@Override
	public long getItemId(int position) {
		return position;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		// get the selected entry
		ApplicationInfo entry = mListAppInfo.get(position);

		// reference to convertView
		View v = convertView;

		// inflate new layout if null
		if(v == null) {
			LayoutInflater inflater = LayoutInflater.from(mContext);
			v = inflater.inflate(R.layout.layout_appinfo, null);
		}

		// load controls from layout resources
		ImageView ivAppIcon = (ImageView)v.findViewById(R.id.ivIcon);
		TextView tvAppName = (TextView)v.findViewById(R.id.tvName);
		TextView tvPkgName = (TextView)v.findViewById(R.id.tvPack);

		// set data to display
		ivAppIcon.setImageDrawable(entry.loadIcon(mPackManager));
		tvAppName.setText(entry.loadLabel(mPackManager));
		tvPkgName.setText(entry.packageName);

		// return view
		return v;
	}
}

2. Utilities: (Utilities.java)

package pete.android.study;

import java.util.List;

import android.content.ActivityNotFoundException;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.widget.Toast;

public class Utilities {

	/*
	 * Get all installed application on mobile and return a list
	 * @param	c	Context of application
	 * @return	list of installed applications
	 */
	public static List getInstalledApplication(Context c) {
		return c.getPackageManager().getInstalledApplications(PackageManager.GET_META_DATA);
	}

	/*
	 * Launch an application
	 * @param	c	Context of application
	 * @param	pm	the related package manager of the context
	 * @param	pkgName	Name of the package to run
	 */
	public static boolean launchApp(Context c, PackageManager pm, String pkgName) {
		// query the intent for lauching
		Intent intent = pm.getLaunchIntentForPackage(pkgName);
		// if intent is available
		if(intent != null) {
			try {
				// launch application
				c.startActivity(intent);
				// if succeed
				return true;

			// if fail
			} catch(ActivityNotFoundException ex) {
				// quick message notification
				Toast toast = Toast.makeText(c, "Application Not Found", Toast.LENGTH_LONG);
				// display message
				toast.show();
			}
		}
		// by default, fail to launch
		return false;
	}
}

3. MainActivity: (MainActivity.java)

package pete.android.study;

import android.app.Activity;
import android.content.pm.ApplicationInfo;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.AdapterView.OnItemClickListener;

public class MainActivity extends Activity {
    private ListView mListAppInfo;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // set layout for the main screen
        setContentView(R.layout.layout_main);

        // load list application
        mListAppInfo = (ListView)findViewById(R.id.lvApps);
        // create new adapter
        AppInfoAdapter adapter = new AppInfoAdapter(this, Utilities.getInstalledApplication(this), getPackageManager());
        // set adapter to list view
        mListAppInfo.setAdapter(adapter);
        // implement event when an item on list view is selected
        mListAppInfo.setOnItemClickListener(new OnItemClickListener() {
        	@Override
        	public void onItemClick(AdapterView parent, View view, int pos, long id) {
        		// get the list adapter
        		AppInfoAdapter appInfoAdapter = (AppInfoAdapter)parent.getAdapter();
        		// get selected item on the list
        		ApplicationInfo appInfo = (ApplicationInfo)appInfoAdapter.getItem(pos);
        		// launch the selected application
        		Utilities.launchApp(parent.getContext(), getPackageManager(), appInfo.packageName);
        	}
		});
    }
}

F – Note

- Using the tip of retrieving the list of installed application.

- Using the tip of launching an activity from another.

- Performance is not so good , of course. You can think of better solution than mine!

- The code is toooo simple, I guess!

G – Get the Sample Project by Pete

Pick your favorite file hosting server: Mediafire | Rapidshare | Megaupload

H – Final Words

- Have you learned something?

- Is it easy to understand?

- Make sure you practice day by day with me , it’s fun, isn’t it?

- Hope you enjoy it!

Cheers,

Pete Houston

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