Previous fragment visible under the new fragment issue

[Pavlex4]

I have created android application with navigation drawer and when I click item from navigation drawer old fragment is not replaced,I can still see the old fragment under the new fragment.How to fix this issue?

private void displaySelectedScreen(int id)
{
Fragment fragment = null;

        switch (id)
        {
            case R.id.home:
                fragment = new Main();
                break;
            case R.id.settings:
                Intent intent = new Intent(this, Settings.class);
                startActivity(intent);
                break;
            case R.id.about:
                Intent intent1 = new Intent(this, About.class);
                startActivity(intent1);
                break;
            case R.id.share:
                try
                {
                    Intent i = new Intent(Intent.ACTION\_SEND);
                    i.setType("text/plain");
                    i.putExtra(Intent.EXTRA\_SUBJECT, "Audiophileradio");
                    String sAux = "\\nLet me recommend you this application\\n\\n";
                    sAux = sAux + "https://play.google.com/store/apps/details?id=Orion.Soft \\n\\n";
                    i.putExtra(Intent.EXTRA\_TEXT, sAux);
                    startActivity(Intent.createChooser(i, "choose one"));
                }
                catch(Exception e)
                {
                    //e.toString();
                }
                break;
            case R.id.send:
                fragment = new Feedback();
                break;
        }
        if (fragment != null)
        {
            FragmentManager fragmentManager = getSupportFragmentManager();
            fragmentManager.beginTransaction()
                    .replace(R.id.contentFrame, fragment).commit();
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer\_layout);
        drawer.closeDrawer(GravityCompat.START);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item)
    {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        displaySelectedScreen(id);

        return true;
    }

content_main.xml

[David Crow]

See here.

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