ActionBar - Back Button

// 1
    getActionBar().setDisplayHomeAsUpEnabled(true);
// 2
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
            switch (item.getItemId()) {
            case android.R.id.home:
                onBackPressed();
                return true;
            }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onBackPressed() {
        super.onBackPressed();
    }