IntelliJ更改了Android Studio中的“导航抽屉”模板“ Activity ”，从而减少了“ Activity ”类中的代码行。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;
}
}
这里最值得注意的变化之一是方法:
onNavigationItemSelected(MenuItem item)此方法的旧导航抽屉模板的定义为:
onNavigationItemSelected(int position, long itemId)您可以通过删除内部
PlaceHolderFragment类，创建自己的片段和布局并执行以下操作来修改旧模板: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(至少据我所知)。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。这可能是由于以下原因导致的:
transaction.replace(R.id.drawer_layout, fragment);
片段应替换为
FrameLayout，旧的导航抽屉布局如下所示:<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"/>
但是新的看起来像这样:
<?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，如何修改新模板以便能够在Fragments之间切换？
最佳答案
因此，基于@ L.L。的答案，我能够解决此问题。
首先，将FrameLayout添加到content_main.xml文件:
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent" android:id="@+id/content_frame"/>
在您的
MainActivity(或您在导航抽屉中命名为Activity的任何名称)中，定义一个名为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);
}
在3个自定义片段之间切换； NewsFragment，EventsFragment和GalleryFragment。
在菜单
activity_main_drawer中，我将内容更改为此:<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
onNavigationItemSelected方法中的Activity类做这个:
@Override
public boolean onNavigationItemSelected(MenuItem item) {
displayView(item.getItemId());
return true;
}
最后，您的onCreate方法中的最后一条语句:
@Override
protected void onCreate(Bundle savedInstanceState) {
....
....
displayView(R.id.nav_news);
}
这是因为我希望用户看到的第一个 View 是“新闻”。将其更改为您选择的任何 View 。
处理返回新闻事件:
就目前而言，如果您从任何Fragments中按返回按钮，该应用程序都会退出。我希望当用户按下Back按钮时，我的应用程序返回到News Fragment(我的家庭片段)。所以我这样做:
声明了一个 bool(boolean) 变量:
private boolean viewIsAtHome;
然后在
displayView()方法中，我这样做: 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()方法的外部创建一个类似于的新方法:@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
}
}
为我工作。