Android Market Optimization

This subject also known as App Store Optimization (ASO). Few people started to write posts on this subject for Android, this post is an on-going work to collect links to those posts:

• There's a series of posts on Droid-Blog blog: Keyworks & Description, Icons, Graphics & Videos
• A post called Hacking the app stores

Android promotion: pay per install

I tried looking for ways to promote Android apps. It was hard. Why companies aren't saying: we're doing Pay-Per-Install campaigns? (alternative names include: Cost-Per-Install, CPI, Cost-Per-Action, CPA)

Here's a list of pay-per-install for Android I've found so far (on going work, please correct me if there's something wrong here):

• AppBrain - Free apps only, Minimum bid: 0.20$, minimal daily budget: 25$, minimal campaign budget: 100$. See more details here. No SDK integration required,
• TapJoy - Pay-per-install plus optional pay-per-action (which probably cost much more). Minimum bid: 0.10$ for rewarded install. SDK integration required. Does not accept PayPal.
• Flurry AppCircle - Free & paid apps. Minimum bid: 0.75$
• Everbadge - Free & paid apps. Minimum bid: 0.15$. SDK integration required,
• AppRedeem - Free & paid apps. Minimum bid: 0.50$ (paid apps), 0.15$ (free apps)
• PlayMobs - Minimum bid: 0.10$ for rewarded install. No SDK integration required.

Possible Pay Per Install, not sure:

• HeyZap - ???
• RadiumOne - ???
• W3I - ???
• Appia - ???
• Zedge - ???

References:

• https://groups.google.com/forum/#!msg/android-discuss/tlYilbiPhDc/nxKsnze59tEJ
• User comment: updated Everbadge minimum bid.

Downloading Android source code on Windows

Here's the short-short version:

1. Download and install command line Git client: msysgit.
2. Download the root Android project using Git.exe (located in /bin folder of msysgit)
   git clone https://android.googlesource.com/platform/manifest
3. In the target folder you'll find few XML files. Open default.xml. You can see multiple tags . Choose the project you want to download. You need the name attribute of the project. Write the following line to download:
   git clone https://android.googlesource.com/

Example:
To download the most interesting project (IMHO) frameworks/base, the GIT command is:
git clone https://android.googlesource.com/platform/frameworks/base

Projects of interest:

• packages/apps/XXXX - The project names of the apps that comes bundled with Android (excluding proprietry Google apps such as the Android Market) such as the Gallery, Camera etc.
• external/XXXX - 3rd party software (ping, bzip, etc).
• frameworks/base - The sources of the Java system.
  

Android (Java) object pool

There are many ways to implement an object pool. Here's the way it's implemented in some classes in Android (Message, MotionEvent, Parcel, VelocityTracker):

private MyObjectName mNext;
private static Object gPoolSync = new Object();
private static MyObjectName gPool;
private static int gPoolSize = 0;
private static final int MAX_POOL_SIZE = 10;

public static MyObjectName obtain() {
  synchronized (gPoolSync) {
    if (gPool != null) {
      MyObjectName m = gPool;
      gPool = m.mNext;
      m.mNext = null;
      gPoolSize--;
      return m;
    }
  }
  return new MyObjectName();
}

public void recycle() {
  synchronized (gPoolSync) {
    if (gPoolSize < MAX_POOL_SIZE) {
      // Perform object data cleaning and data releasing before recycling
      clearForRecycle();
                
      mNext = gPool;
      gPool = this;
      gPoolSize++;
    }
  }
}

Reducing ArrayList add()/remove() memory re-allocation/shifts

This post is Android related, but probably goes to all java systems.

Reason: ArrayList implementation is based on an array, with a pointers to the start and end of the array.
(1) When you remove the first or last items, the pointers are moved. If you remove and items from the middle all the items after the removed location are shifted.
(2) After many removes/adds the start pointer is set so high the ArrayList is forced to shift all the items.

Solution: when removing item - swap the item with the last item, and remove the last item. Drawback - you lose the order of the items in the ArrayList.

import java.util.ArrayList;
import java.util.ArrayList;
import java.util.Collection;

public class SwapArrayList extends ArrayList {
 private static final long serialVersionUID = 2995040970224168173L;

 public SwapArrayList() {
        this(0);
    }

    public SwapArrayList(int capacity) {
     super(capacity);
    }

    public SwapArrayList(Collection collection) {
     super(collection);
    }
    
    @Override
    public boolean remove(Object object) {
        int index = indexOf(object);
        if (index >= 0) {
         int size = this.size();
         if (index < size - 1) {
          // Swap the last item with the item to be removed
       E tmp = this.get(size - 1);
       this.set(size - 1, this.get(index));
       this.set(index, tmp);
       index = size - 1;
         }
         
            remove(index);
            return true;
        }
        return false;
    }
    
    @Override
    public E remove(int location) {
     int size = this.size();
     if (0 <= location && location < size) {
      if (location < size - 1) {
       // Swap the last item with the item to be removed
       E tmp = this.get(size - 1);
       this.set(size - 1, this.get(location));
       this.set(location, tmp);
       location = size - 1;
      }
     } else {
      throw new IndexOutOfBoundsException();
     }
     
     return super.remove(location);
    }
}

onKeyDown/onKeyUp/onTrackballEvent does not fire in a View

When trying to get keypad events in a view, the view does not get those events unless explicitly sent by the Activity, so to fix this add the following code in the Activity:

@Override
public boolean onTrackballEvent(MotionEvent event) {
    if (mView.dispatchTrackballEvent(event) == true)
        return true;
       
    return super.onTrackballEvent(event);
}

Finding table by column name in a database

From time to time I need to find a table in a database which I know the column name but I have to search for the table.

Here's how to do it in Oracle:
SELECT TABLE_NAME, COLUMN_NAME
FROM USER_TAB_COLUMNS -- COLS,
WHERE COLUMN_NAME = 'ColumnNameHere'
GROUP BY TABLE_NAME, COLUMN_NAME;

Here's how to do it in SQL Server:
SELECT obj.Name, col.Name
FROM sysobjects obj, syscolumns col
WHERE obj.id = col.id
AND col.Name = 'ColumnNameHere'