ExpandSearchViewToEntireActionbar.java

@Override
public boolean onCreateOptionsMenu(final Menu menu) {
    getMenuInflater().inflate(R.menu.menu_main, menu);

    final MenuItem searchItem = menu.findItem(R.id.search);
    SearchView searchView = (android.widget.SearchView) searchItem.getActionView();

    // Detect SearchView icon clicks
    searchView.setOnSearchClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            setItemsVisibility(menu, searchItem, false);
        }
    });
    // Detect SearchView close
    searchView.setOnCloseListener(new SearchView.OnCloseListener() {
        @Override
        public boolean onClose() {
            setItemsVisibility(menu, searchItem, true);
            return false;
        }
    });

    return super.onCreateOptionsMenu(menu);
}

private void setItemsVisibility(Menu menu, MenuItem exception, boolean visible) {
    for (int i=0; i<menu.size(); ++i) {
        MenuItem item = menu.getItem(i);
        if (item != exception) item.setVisible(visible);
    }
}