Question

I would like to dynamically change the “home” icon in the ActionBar. This is easily done in v14 with ActionBar.setIcon(…), but I can’t find anyway to accomplish this in previous versions.

Answer 1

If you are using the ActionbarCompat code provided by google, you can access the home icon via the ActionBarHelperBase.java class for API v4 onwards.

    //code snippet from ActionBarHelperBase.java
    ...
    private void setupActionBar() {
    final ViewGroup actionBarCompat = getActionBarCompat();
    if (actionBarCompat == null) {
        return;
    }

    LinearLayout.LayoutParams springLayoutParams = new LinearLayout.LayoutParams(
            0, ViewGroup.LayoutParams.MATCH_PARENT);
    springLayoutParams.weight = 1;

    // Add Home button
    SimpleMenu tempMenu = new SimpleMenu(mActivity);
    SimpleMenuItem homeItem = new SimpleMenuItem(tempMenu,
            android.R.id.home, 0, mActivity.getString(R.string.app_name));
    homeItem.setIcon(R.drawable.ic_home_ftn);
    addActionItemCompatFromMenuItem(homeItem);

    // Add title text
    TextView titleText = new TextView(mActivity, null,
            R.attr.actionbarCompatTitleStyle);
    titleText.setLayoutParams(springLayoutParams);
    titleText.setText(mActivity.getTitle());
    actionBarCompat.addView(titleText);
}
...

You should be able to modify the code to the home button accessible to the activities that extend ActionBarActivity and change it that way.

Honeycomb seems a little harder and it doesn’t seem to give such easy access. At a guess, its id should also be android.R.id.home so you may be able to pull that from the view in ActionBarHelperHoneycomb.java