[Android] Set Default Activity (Now investigating to find a way to set a default activity especially for Home)

Here is what I have found during the investigation.

Check is Preferred Activity is set (InstalledAppDetails.java)
------------------------
// Get list of preferred activities
mActivitiesButton = (Button)findViewById(R.id.clear_activities_button);
List prefActList = new ArrayList();
// Intent list cannot be null. so pass empty list
List intentList = new ArrayList();
mPm.getPreferredActivities(intentList, prefActList, packageName);
if(localLOGV) Log.i(TAG, "Have "+prefActList.size()+" number of activities in prefered list");
TextView autoLaunchView = (TextView)findViewById(R.id.auto_launch);
if(prefActList.size() <= 0) {
// Disable clear activities button
autoLaunchView.setText(R.string.auto_launch_disable_text);
mActivitiesButton.setEnabled(false);
} else {
autoLaunchView.setText(R.string.auto_launch_enable_text);
mActivitiesButton.setOnClickListener(this);
}

getPreferredActivities() will return not-zero number for the packageName.
If 'preActList" > 0, it is preferred activity set.


Clear the Preferred (or Default) Activity (InstalledAppDetails.java)
-------------------------------
} else if(v == mActivitiesButton) {
mPm.clearPackagePreferredActivities(packageName);
mActivitiesButton.setEnabled(false);


Set the Preferred Activity
-------------------------------
ResolveInfo ri = mAdapter.resolveInfoForPosition(which);
Intent intent = mAdapter.intentForPosition(which);

if ((mAlwaysCheck != null) && mAlwaysCheck.isChecked()) {
// Build a reasonable intent filter, based on what matched.
IntentFilter filter = new IntentFilter();

if (intent.getAction() != null) {
filter.addAction(intent.getAction());
}
Set categories = intent.getCategories();
if (categories != null) {
for (String cat : categories) {
filter.addCategory(cat);
}
}
filter.addCategory(Intent.CATEGORY_DEFAULT);

int cat = ri.match&IntentFilter.MATCH_CATEGORY_MASK;
Uri data = intent.getData();
if (cat == IntentFilter.MATCH_CATEGORY_TYPE) {
String mimeType = intent.resolveType(this);
if (mimeType != null) {
try {
filter.addDataType(mimeType);
} catch (IntentFilter.MalformedMimeTypeException e) {
Log.w("ResolverActivity", e);
filter = null;
}
}
} else if (data != null && data.getScheme() != null) {
filter.addDataScheme(data.getScheme());

// Look through the resolved filter to determine which part
// of it matched the original Intent.
Iterator aIt = ri.filter.authoritiesIterator();
if (aIt != null) {
while (aIt.hasNext()) {
IntentFilter.AuthorityEntry a = aIt.next();
if (a.match(data) >= 0) {
int port = a.getPort();
filter.addDataAuthority(a.getHost(),
port >= 0 ? Integer.toString(port) : null);
break;
}
}
}
Iterator pIt = ri.filter.pathsIterator();
if (pIt != null) {
String path = data.getPath();
while (path != null && pIt.hasNext()) {
PatternMatcher p = pIt.next();
if (p.match(path)) {
filter.addDataPath(p.getPath(), p.getType());
break;
}
}
}
}

if (filter != null) {
final int N = mAdapter.mList.size();
ComponentName[] set = new ComponentName[N];
int bestMatch = 0;
for (int i=0; i ResolveInfo r = mAdapter.mList.get(i).ri;
set[i] = new ComponentName(r.activityInfo.packageName,
r.activityInfo.name);
if (r.match > bestMatch) bestMatch = r.match;
}
getPackageManager().addPreferredActivity(filter, bestMatch, set,
intent.getComponent());
}
}


There is no way to set a preferred Home on the first boot up of the device.
I am considering 2 methods to do that.
1) Modify startHomeActivity() API in ActivityManagerService.java
2) Add a persistent Service and set preferred home on boot up. (This could be possible. Because all persistent services start before Home activity)