Android: Can't Change Navigationicon Of V7 Support Toolbar

I'm developing an Activity using SDK v22 (I use targetSDKVersion 22 e minSdkVersion 18 for backward compatibility). My activity uses a navigationbar called by the AppBar. I would

Solution 1:

Try to move your setNavigationIcon code below toggle.syncState(),like this:

    ...    
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();
    toolbar.setNavigationIcon(R.drawable.icon_nav);

Reference here.