如何在 oncreate 活动上设置默认的 naviagationdrawer 片段

Question

我尝试了很多片段事务方式，但我的默认片段在打开 navigationdrawer 活动时没有启动。

     public class MainActivity extends AppCompatActivity{
    private DrawerLayout drawerLayout;
    private NavigationView navigationView;
    private int mSelectedId;

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


        Toolbar toolbar = (Toolbar)findViewById(R.id.tool_bar);
        toolbar.setNavigationIcon(R.drawable.nav_icon);
        setSupportActionBar(toolbar);

        drawerLayout = (DrawerLayout)findViewById(R.id.drawer_layout);
        navigationView = (NavigationView)findViewById(R.id.nvView);
        setupDrawerContent(navigationView);

        mSelectedId = R.id.home;
        selectDrawerItem(mSelectedId);



    }


    private void setupDrawerContent(NavigationView navigationView) {
        navigationView.setNavigationItemSelectedListener(
                new NavigationView.OnNavigationItemSelectedListener() {
                    @Override
                    public boolean onNavigationItemSelected(MenuItem menuItem) {
                        selectDrawerItem(menuItem.getItemId());
                        return true;
                    }
                });
    }
//    @Override
//    public boolean onCreateOptionsMenu(Menu menu) {
//        // Inflate the menu; this adds items to the action bar if it is present.
//        getMenuInflater().inflate(R.menu.menu_main, menu);
//        return true;
//    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        switch (item.getItemId()) {
            case android.R.id.home:
                drawerLayout.openDrawer(GravityCompat.START);
                return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
    }

    public void selectDrawerItem(int mSelectedId) {
        // Create a new fragment and specify the planet to show based on
        // position
        Fragment fragment = null;

        Class fragmentClass;
        switch(mSelectedId) {
            case R.id.home:
                fragmentClass = Main.class;
                break;
            case R.id.orderhistory:
                fragmentClass = Order_history.class;
                break;
            case R.id.profile:
                fragmentClass = Profile.class;
                break;
            case R.id.contact:
                fragmentClass = Contact.class;
                break;
            case R.id.polices:
                fragmentClass = polices.class;
                break;
            default:
                fragmentClass = Main.class;
        }

        try {
            fragment = (Fragment) fragmentClass.newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }

        // Insert the fragment by replacing any existing fragment
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.flContent, fragment);
        fragmentTransaction.commit();

        // Highlight the selected item, update the title, and close the drawer
//        menuItem.setChecked(true);
//        setTitle(menuItem.getTitle());
        drawerLayout.closeDrawers();
    }
}

它在启动时仍然首先显示活动。请传递建议，以便我可以继续前进。

Activity_main.xml

    <android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/drawer_layout"
    tools:context="in.co.blogspot.mellow.mellow.MainActivity">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <include
        android:id= "@+id/tool_bar"
        layout= "@layout/tool_bar"></include>

    <FrameLayout
        android:id="@+id/flContent"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

    <android.support.design.widget.NavigationView
        android:id="@+id/nvView"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@android:color/white"
        app:menu="@menu/drawer_view" />

</android.support.v4.widget.DrawerLayout>

主类

public class Main extends Fragment {
    public static TabLayout tabLayout;
    public static ViewPager viewPager;
    public static int int_items = 3 ;

    public Main() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main,null);
        tabLayout = (TabLayout) rootView.findViewById(R.id.tabs);
        viewPager = (ViewPager) rootView.findViewById(R.id.viewpager);

        /**
         *Set an Apater for the View Pager
         */
        viewPager.setAdapter(new MyAdapter(getChildFragmentManager()));

        /**
         * Now , this is a workaround ,
         * The setupWithViewPager dose't works without the runnable .
         * Maybe a Support Library Bug .
         */

        tabLayout.post(new Runnable() {
            @Override
            public void run() {
                tabLayout.setupWithViewPager(viewPager);
            }
        });

        // Inflate the layout for this fragment
        return rootView;
    }

    class MyAdapter extends FragmentPagerAdapter {

        public MyAdapter(FragmentManager fm) {
            super(fm);
        }

        /**
         * Return fragment with respect to Position .
         */

        @Override
        public Fragment getItem(int position)
        {
            switch (position){
                case 0 : return new p1();
                case 1 : return new p2();
                case 2 : return new p3();
            }
            return null;
        }

        @Override
        public int getCount() {

            return int_items;

        }

Answer 1

我认为您可以更改一些代码。

以这种方式 selectDrawerItem(int mSelectedId) 更改您的方法 selectDrawerItem 以便您可以接收 菜单的 ID 而不是菜单，因此在 onCreate() 方法中您可以执行类似的操作

主活动

public class MainActivity extends AppCompatActivity {

    private DrawerLayout drawerLayout;
    private NavigationView navigationView;
    private int mSelectedId;

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

        drawerLayout = (DrawerLayout)findViewById(R.id.drawer_layout);
        navigationView = (NavigationView)findViewById(R.id.nvView);
        setupDrawerContent(navigationView);

        mSelectedId = R.id.orderhistory;
        selectDrawerItem(mSelectedId);

    }


    private void setupDrawerContent(NavigationView navigationView) {
        navigationView.setNavigationItemSelectedListener(
                new NavigationView.OnNavigationItemSelectedListener() {
                    @Override
                    public boolean onNavigationItemSelected(MenuItem menuItem) {
                        selectDrawerItem(menuItem.getItemId());
                        return true;
                    }
                });
    }
//    @Override
//    public boolean onCreateOptionsMenu(Menu menu) {
//        // Inflate the menu; this adds items to the action bar if it is present.
//        getMenuInflater().inflate(R.menu.menu_main, menu);
//        return true;
//    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        switch (item.getItemId()) {
            case android.R.id.home:
                drawerLayout.openDrawer(GravityCompat.START);
                return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
    }

    public void selectDrawerItem(int mSelectedId) {
        // Create a new fragment and specify the planet to show based on
        // position
        Fragment fragment = null;

        Class fragmentClass;
        switch(mSelectedId) {
            case R.id.home:
                fragmentClass = Main.class;
                break;
            case R.id.orderhistory:
                fragmentClass = Order_history.class;
                break;
            default:
                fragmentClass = Main.class;
        }

        try {
            fragment = (Fragment) fragmentClass.newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }

        // Insert the fragment by replacing any existing fragment
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.flContent, fragment);
        fragmentTransaction.commit();

        // Highlight the selected item, update the title, and close the drawer
//        menuItem.setChecked(true);
//        setTitle(menuItem.getTitle());
        drawerLayout.closeDrawers();
    }
}

activity_main.xml

<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/drawer_layout">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <FrameLayout
            android:id="@+id/flContent"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

    </LinearLayout>

    <android.support.design.widget.NavigationView
        android:id="@+id/nvView"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@android:color/white"
        app:menu="@menu/drawer_view" />

</android.support.v4.widget.DrawerLayout>

drawer_view.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/home"
        android:title="Home"
        />

    <item
        android:id="@+id/orderhistory"
        android:title="Cursos"
        />
</menu>

Order_history.java

public class Order_history extends Fragment {


    public Order_history() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_order_history, container, false);
    }

}

fragment_order_history.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.enterprise.prueba.Order_history">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment" />

</FrameLayout>

Main.Java

public class Main extends Fragment {

    public Main() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, null);


        // Inflate the layout for this fragment
        return rootView;
    }
}

fragment_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="I'm a fragment"/>

</LinearLayout>

已编辑

这很奇怪，现在我用相同的代码创建了一个新项目，这是我在 Oncreate() 中选择订单历史时的结果。

我更新我的代码以显示所有文件