IntelliJ 对 Android Studio 中的 Navigation Drawer 模板 Activity 进行了更改,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
类来修改旧模板,创建自己的 fragment 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(至少据我所知不是)。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 home
布局的布局也显示在 news
布局中。
这可能是因为以下行:
transaction.replace(R.id.drawer_layout, fragment);
fragment 应该在 FrameLayout
中被替换,旧的 Navigation Drawer 布局看起来像这样:
<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 fragment 之间切换?
最佳答案
所以,根据@L.L. 的回答,我能够解决这个问题。
首先,将你的 FrameLayout 添加到你的 content_main.xml
文件中:
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent" android:id="@+id/content_frame"/>
在你的 MainActivity
(或任何你用抽屉导航命名的 Activity )定义一个名为 displayView
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 fragment 之间切换; NewsFragment、EventsFragment 和 GalleryFragment。
在我的菜单activity_main_drawer
我已经把内容改成了这样:
<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,在您的 onNavigationItemSelected
方法中
这样做:
@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);
}
这是因为我希望我的用户看到的第一个 View 是新闻。将其更改为您选择的任何内容。
处理后按事件:
就目前而言,如果您按下任何 fragment 的后退按钮,应用程序将退出。我希望我的应用程序在用户按下后退按钮时返回新闻 fragment (我的主页 fragment )。所以我这样做了:
声明一个 bool 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()
方法之外创建一个类似 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。
关于android - 在新的 Navigation Drawer Activity 模板中使用 onNavigationItemSelected 在 Fragments 之间切换(Android Studio 1.4 及更高版本),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/32944798/