在新的导航抽屉活动模板中使用onNavigationItemSelected在片段之间切换（Android Studio 1.4以后）

Question

IntelliJ在Android Studio中对Navigation Drawer模板Activity进行了更改，Activity类中的代码行更少。 新的Activity类如下所示：

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    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();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);
}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}


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

    if (id == R.id.nav_camara) {
        // Handle the camera action
    } else if (id == R.id.nav_gallery) {

    } else if (id == R.id.nav_slideshow) {

    } else if (id == R.id.nav_manage) {

    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_send) {

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}
}

这里最显着的变化之一是方法：

onNavigationItemSelected(MenuItem item)

旧的Navigation Drawer模板对此方法的定义是：

onNavigationItemSelected(int position, long itemId)

您可以通过删除内部PlaceHolderFragment类来修改该旧模板，创建自己的片段和布局，并执行以下操作：

Fragment fragment = null;
switch (position) {
    case 0:
        fragment = new FragmentA();
        break;
    case 1:
        fragment = new FragmentB();
        break;
    default:
        break;
}

if (fragment != null) {
    FragmentManager fragmentManager = getSupportFragmentManager();
    fragmentManager.beginTransaction()
            .replace(R.id.frame_container, fragment).commit();

}

但这不适用于新模板（至少不是我的小知识）。 我试过了：

 public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();
    Snackbar snackbar = Snackbar.make(findViewById(android.R.id.content), item.getTitle() + " clicked", Snackbar.LENGTH_SHORT);
    Fragment fragment = null;
    switch (id) {
        case R.id.nav_home:
            fragment = HomeFragment.getFragInstance();
            break;

        case R.id.nav_news:

            fragment = NewsFragment.getFragInstance();
            break;


        default:
            break;
    }

    if (fragment != null) {
        FragmentTransaction transaction = fragmentManager.beginTransaction();
        transaction.addToBackStack(null);
        transaction.replace(R.id.drawer_layout, fragment);
        transaction.commit();


        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);

    }
    return true;
}

但是home布局的布局也显示在news布局中。 这可能是因为这条线：

transaction.replace(R.id.drawer_layout, fragment);

片段应该在FrameLayout替换，旧的Navigation Drawer布局如下所示：

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

<!-- Framelayout to display Fragments -->
<FrameLayout
    android:id="@+id/frame_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<!-- Listview to display slider menu -->


<ListView
    android:id="@+id/list_sliderMenu"
    android:layout_width="240dp"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:choiceMode="singleChoice"
    android:divider="@color/white"
    android:dividerHeight="1dp"
    android:listSelector="@drawable/list_selector"
    android:background="@color/list_background"/>

但新的看起来像这样：

 <?xml version="1.0" encoding="utf-8"?>
  <android.support.v4.widget.DrawerLayout      
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:id="@+id/drawer_layout"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:fitsSystemWindows="true"
   tools:openDrawer="start">

<include
    layout="@layout/app_bar_base"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<android.support.design.widget.NavigationView
    android:id="@+id/nav_view"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:fitsSystemWindows="true"
    app:headerLayout="@layout/nav_header_base"
    app:menu="@menu/activity_base_drawer" />

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

长话短说，如何修改新模板才能在片段之间切换？

Answer 1

所以，基于@LL的答案，我能够解决这个问题。

首先，将FrameLayout添加到content_main.xml文件中：

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

在MainActivity （或者您使用导航抽屉命名Activity的任何内容）定义名为displayView的方法

 public void displayView(int viewId) {

    Fragment fragment = null;
    String title = getString(R.string.app_name);

    switch (viewId) {
        case R.id.nav_news:
            fragment = new NewsFragment();
            title  = "News";

            break;
        case R.id.nav_events:
            fragment = new EventsFragment();
            title = "Events";
            break;

    }

    if (fragment != null) {
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.content_frame, fragment);
        ft.commit();
    }

    // set the toolbar title
    if (getSupportActionBar() != null) {
        getSupportActionBar().setTitle(title);
    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);

}

我在3个自定义碎片之间切换; NewsFragment，EventsFragment和GalleryFragment。

在我的菜单activity_main_drawer我已将内容更改为：

<menu xmlns:android="http://schemas.android.com/apk/res/android">

<group android:checkableBehavior="single">
    <item android:id="@+id/nav_news"  
        android:icon="@android:drawable/ic_menu_news"
        android:title="News" />
    <item android:id="@+id/nav_events" 
        android:icon="@android:drawable/ic_menu_events"
        android:title="Events" />
    <item android:id="@+id/nav_gallery" 
        android:icon="@android:drawable/ic_menu_gallery"
        android:title="Gallery" />
  </group>
</menu>

回到Activity类，在onNavigationItemSelected方法中执行以下操作：

@Override
public boolean onNavigationItemSelected(MenuItem item) {
    displayView(item.getItemId());
    return true;
}

最后，你的onCreate方法中的最后一个语句：

 @Override
protected void onCreate(Bundle savedInstanceState) {
    ....
    ....
    displayView(R.id.nav_news);
}

这是因为我希望我的用户看到的第一个视图是News.Change它为您选择的任何内容。

处理新闻事件：

就目前而言，如果您按下任何片段中的后退按钮，应用程序将退出。当用户按下后退按钮时，我希望我的应用程序返回到新闻片段（我的主片段）。 所以我这样做了：

声明了一个布尔变量：

private boolean viewIsAtHome;

然后在displayView()方法中我这样做了：

 public void displayView(int viewId){
    Fragment fragment = null;
    String title = getString(R.string.app_name);

    switch (viewId) {
        case R.id.nav_news:
            fragment = new NewsFragment();
            title  = getString(R.string.news_title);
            viewIsAtHome = true;

            break;
        case R.id.nav_events:
            fragment = new EventsFragment();
            title = getString(R.string.events_title);
            viewIsAtHome = false;
            break;

        case R.id.nav_gallery:
            fragment = new GalleryFragment();
            title = getString(R.string.gallery_title);
            viewIsAtHome = false;
            break;

最后，删除旧的onBackPressed方法并在onCreate()方法之外创建一个这样的新方法：

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    }
    if (!viewIsAtHome) { //if the current view is not the News fragment
        displayView(R.id.nav_news); //display the News fragment
    } else {
        moveTaskToBack(true);  //If view is in News fragment, exit application
    }
}

适合我。

Answer 2

您不应该更改DrawerLayout ，只需要在“content_main.xml”中添加一个框架。

请按照以下步骤操作：

1. 打开位于“layout”文件夹中的“content_main.xml”文件。

2. 使用以下代码：

    <?xml version="1.0" encoding="utf-8"?> <RelativeLayout 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" app:layout_behavior="@string/appbar_scrolling_view_behavior" tools:showIn="@layout/app_bar_main" tools:context=".MainActivity"> <FrameLayout android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/mainFrame"> </FrameLayout> </RelativeLayout> 

3. 转到onNavigationItemSelected方法：

    public boolean onNavigationItemSelected(MenuItem item) { int id = item.getItemId(); Fragment fragment; if (id == R.id.nav_camara) { fragment = new YourFragment(); FragmentTransaction ft = getSupportFragmentManager().beginTransaction(); ft.replace(R.id.mainFrame, fragment); ft.commit(); } else if (id == R.id.nav_gallery) { } else if (id == R.id.nav_slideshow) { } else if (id == R.id.nav_manage) { } else if (id == R.id.nav_share) { } else if (id == R.id.nav_send) { } DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); drawer.closeDrawer(GravityCompat.START); return true; } 

Answer 3

另一种方式是：

public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    Fragment fragment;
    int id = item.getItemId();

    if (id == R.id.nav_camera) {
        // Handle the camera action
        fragment = new BlankFragment();
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.container_new, fragment);
        ft.commit();
    } else if (id == R.id.nav_gallery) {
        fragment = new HorizontalView();
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.container_new,fragment);
        ft.commit();
    } else if (id == R.id.nav_slideshow) {
        fragment = new FragmentVerticleView();
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.container_new,fragment);
        ft.commit();

    } else if (id == R.id.nav_manage) {

    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_send) {

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

然后，您需要将所有片段实现到您的活动中。 就我而言，它是

MainActivity.java

    public class MainActivity extends AppCompatActivity
    implements BlankFragment.OnFragmentInteractionListener, HorizontalView.OnFragmentInteractionListener,FragmentVerticleView.OnFragmentInteractionListener,OnNavigationItemSelectedListener
     { 
    //coding stuff
    }

并处理片段java文件中抛出的异常

    "must implement OnFragmentInteractionListener"

你只需添加以下方法

      public void    onFragmentInteraction(Uri uri){
    //We can keep this empty
}

你去吧！ 搞定

感谢这个教程打击这个

Answer 4

不确定我是否能够提供帮助，但是如果你想修改NavigationDrawer Activity的布局模板，你可以在<Path\\to\\Program_Files>\\Android\\Android Studio\\plugins\\android\\lib\\templates\\activities\\NavigationDrawerActivity\\root\\res\\layout找到它<Path\\to\\Program_Files>\\Android\\Android Studio\\plugins\\android\\lib\\templates\\activities\\NavigationDrawerActivity\\root\\res\\layout

我相信，最好有一个类似于以下的布局 -

<!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
<android.support.v4.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${relativePackage}.${activityClass}">

    <!-- As the main content view, the view below consumes the entire
         space available using match_parent in both dimensions. -->
    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <!-- android:layout_gravity="start" tells DrawerLayout to treat
         this as a sliding drawer on the left side for left-to-right
         languages and on the right side for right-to-left languages.
         If you're not building against API 17 or higher, use
         android:layout_gravity="left" instead. -->
    <!-- The drawer is given a fixed width in dp and extends the full height of
         the container. -->
    <NavigationView android:id="@+id/navigation_drawer"
        android:layout_width="@dimen/navigation_drawer_width"
        android:layout_height="match_parent"
        android:layout_gravity="<#if buildApi gte 17>start<#else>left</#if>" />

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

这将与您之前更换R.id.container的Fragment的方式一起R.id.container 。

Answer 5

我使用了Android Studio 1.4自动创建的模板，我遇到了和你一样的困难。

首先，我更改了activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools" android:id="@+id/drawer_layout"
android:layout_width="match_parent" android:layout_height="match_parent"
android:fitsSystemWindows="true" tools:openDrawer="start">

<!--Main-->
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <!-- The ActionBar -->
    <include
        layout="@layout/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <FrameLayout
        android:id="@+id/content"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </FrameLayout>
</LinearLayout>

<!--Drawer-->
<android.support.design.widget.NavigationView
    android:id="@+id/nav_view"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:fitsSystemWindows="true"
    app:headerLayout="@layout/nav_header"
    app:menu="@menu/drawer" /></android.support.v4.widget.DrawerLayout>

DrawerLayout包含两部分：

1. 主屏幕（ LinearLayout ）
2. 抽屉（ NavigationView ）

主屏幕包含ActionBar，FrameLayout（ R.id.content ）将被片段替换。 抽屉包含标题和菜单。

因此，我们现在覆盖onNavigationItemSelected并用片段替换R.id.content 。

这是我的MainActivity代码：

    @Override
public boolean onNavigationItemSelected(MenuItem item) {
    Fragment fragment;
    FragmentTransaction ft = getFragmentManager().beginTransaction();
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_A) {
        fragment = new AFragment();
        ft.replace(R.id.content, fragment).commit();        
    } else if (id == R.id.nav_B){
        fragment = new BFragment();
        ft.replace(R.id.content, fragment).commit();
    } else if (id == R.id.nav_settings) {
        Intent intent = new Intent(MainActivity.this, SettingsActivity.class);
        startActivity(intent);
    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

主页也是一个片段。 我在onCreate方法中设置主页，虽然我不确定是否有更好的方法来设置主页面。

//MainPageFragment
    FragmentTransaction ft = getFragmentManager().beginTransaction();
    ft.replace(R.id.content, new MainPageFragment()).commit();

PS。 这是toolbar.xml ，ActionBar

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:fitsSystemWindows="true"
tools:context="jean.yang.MainActivity">
<android.support.design.widget.AppBarLayout android:layout_height="wrap_content"
    android:layout_width="match_parent" android:theme="@style/AppTheme.AppBarOverlay">
    <android.support.v7.widget.Toolbar android:id="@+id/toolbar"
        android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
</android.support.design.widget.CoordinatorLayout>

Answer 6

尝试删除以前的片段或删除所有历史记录而不是添加新片段。

//Here we are clearing back stack fragment entries
int backStackEntry = getSupportFragmentManager().getBackStackEntryCount();
if (backStackEntry > 0) {
    for (int i = 0; i < backStackEntry; i++) {
        getSupportFragmentManager().popBackStackImmediate();
    }
}

//Here we are removing all the fragment that are shown here
if (getSupportFragmentManager().getFragments() != null && getSupportFragmentManager().getFragments().size() > 0) {
    for (int i = 0; i < getSupportFragmentManager().getFragments().size(); i++) {
        Fragment mFragment = getSupportFragmentManager().getFragments().get(i);
        if (mFragment != null) {
            getSupportFragmentManager().beginTransaction().remove(mFragment).commit();
        }
    }
}

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