两个 oncreate(bundle savedinstancestate) 在同一个活动中？

Question

I'm very new to android development and have ran into an issue that I can't seem to get around or get my head around the resolution.

I'm trying to add a navigation drawer to an activity that has a bottom navigation bar in the java program. I've got the XML looking good and working but the below java is reporting the following error:

'onCreate(Bundle)' is already defined in 'MyApp' 

which I understand and can see but I don't know how to resolve it - is it possible?

public class Dash extends AppCompatActivity {
    private DrawerLayout drawer;

    Button signout;
    ChipNavigationBar chipNavigationBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dash);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        signout=findViewById(R.id.logout);
        signout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                FirebaseAuth.getInstance().signOut();
                startActivity(new Intent(getApplicationContext(),Existing.class));
                finish();
            }
        });

        chipNavigationBar = findViewById(R.id.bottom_nav_menu);
        chipNavigationBar.setItemSelected(R.id.bottom_nav_menu, true);
        getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new NewsFragment()).commit();
        bottomMenu();
    }

    private void bottomMenu() {

        chipNavigationBar.setOnItemSelectedListener(new ChipNavigationBar.OnItemSelectedListener() {
            @Override
            public void onItemSelected(int i) {
                Fragment fragment = null;
                switch (i) {
                    case R.id.bottom_nav_menu:
                        fragment = new HomeFragment();
                        break;

                    case R.id.bottom_nav_news:
                        fragment = new NewsFragment();
                        break;

                    case R.id.bottom_nav_profile:
                        fragment = new ProfileFragment();
                        break;
                }
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, fragment).commit();
            }
        });

    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dash);

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        drawer = findViewById(R.id.drawer_layout);

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar,
                R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();
    }
    @Override public void onBackPressed(){
            if (drawer.isDrawerOpen(GravityCompat.START)) {
                drawer.closeDrawer(GravityCompat.START);
            } else {
                super.onBackPressed();
            }
        }
    }

Answer 1

Remove one OnCreate(....)

Try Below Code:

public class Dash extends AppCompatActivity {
    private DrawerLayout drawer;

    Button signout;
    ChipNavigationBar chipNavigationBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dash);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        signout=findViewById(R.id.logout);
        drawer = findViewById(R.id.drawer_layout);

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar,
                R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();
        signout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                FirebaseAuth.getInstance().signOut();
                startActivity(new Intent(getApplicationContext(),Existing.class));
                finish();
            }
        });

        chipNavigationBar = findViewById(R.id.bottom_nav_menu);
        chipNavigationBar.setItemSelected(R.id.bottom_nav_menu, true);
        getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new NewsFragment()).commit();
        bottomMenu();
    }

    private void bottomMenu() {

        chipNavigationBar.setOnItemSelectedListener(new ChipNavigationBar.OnItemSelectedListener() {
            @Override
            public void onItemSelected(int i) {
                Fragment fragment = null;
                switch (i) {
                    case R.id.bottom_nav_menu:
                        fragment = new HomeFragment();
                        break;

                    case R.id.bottom_nav_news:
                        fragment = new NewsFragment();
                        break;

                    case R.id.bottom_nav_profile:
                        fragment = new ProfileFragment();
                        break;
                }
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, fragment).commit();
            }
        });

    }
 
    @Override public void onBackPressed(){
            if (drawer.isDrawerOpen(GravityCompat.START)) {
                drawer.closeDrawer(GravityCompat.START);
            } else {
                super.onBackPressed();
            }
        }
    }