两个oncreate（bundle savedinstancestate）在同一个activity？

Question

我是android开发的新手，遇到了一个问题，我似乎无法绕开，也无法让我的脑袋去解决这个问题。

我正在尝试添加一个导航抽屉的activity有一个底部导航栏在Java程序。我得到了xml看起来很好和工作，但下面的Java报告了以下错误。“'on create（Bundle)'已经在'myapp'中定义了”，我理解并且可以看到，但我不知道如何解决它--这可能吗？

公共类Dash扩展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

删除一个oncreate（。。。。）

请尝试以下代码:

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();
            }
        }
    }