即使在 Stack Overflow 上看到了很多问题，我也没有得到正确的答案，因此写下了这篇文章。我在 View 寻呼机中创建了一个选项卡布局。
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawer"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<android.support.design.widget.CoordinatorLayout
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout
android:id="@+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
<android.support.design.widget.TabLayout
android:id="@+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabGravity="fill"
app:tabMode="scrollable"
app:tabTextAppearance="@style/TabTextAppearance"/>
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</android.support.design.widget.CoordinatorLayout>
<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/navheader"
app:menu="@menu/menu_navigation" />
</android.support.v4.widget.DrawerLayout>
我已经从 Google Code Lab Material Design 编写了这个代码。我的基本要求:
View 分页器中有六个选项卡或 fragment 。相应的六个选项也会出现在拉动抽屉导航时。当我单击抽屉中的某个项目时说项目编号 4，从当前选项卡或 fragment 到相应的第 4 个选项卡或 fragment 必须有一个沼泽。
我主要 Activity 中的代码:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Adding Toolbar to Main screen
mHandler = new Handler();
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Setting ViewPager for each Tabs
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
// Set Tabs inside Toolbar
TabLayout tabs = (TabLayout) findViewById(R.id.tabs);
tabs.setupWithViewPager(viewPager);
// Create Navigation drawer and inlfate layout
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer);
// Adding menu icon to Toolbar
ActionBar supportActionBar = getSupportActionBar();
if (supportActionBar != null) {
VectorDrawableCompat indicator =
VectorDrawableCompat.create(getResources(), R.drawable.ic_menu, getTheme());
indicator.setTint(ResourcesCompat.getColor(getResources(), R.color.white, getTheme()));
supportActionBar.setHomeAsUpIndicator(indicator);
supportActionBar.setDisplayHomeAsUpEnabled(true);
}
// Set behavior of Navigation drawer
navigationView.setNavigationItemSelectedListener(
new NavigationView.OnNavigationItemSelectedListener() {
// This method will trigger on item Click of navigation menu
// public boolean onNavigationItemSelected(MenuItem menuItem) {
// // Set item in checked state
// menuItem.setChecked(true);
//
// // TODO: handle navigation
//
// // Closing drawer on item click
// mDrawerLayout.closeDrawers();
// return true;
// }
@Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
//Check to see which item was being clicked and perform appropriate action
switch (menuItem.getItemId()) {
//Replacing the main content with ContentFragment Which is our Inbox View;
case R.id.nav_home:
navItemIndex = 0;
CURRENT_TAG = TAG_HOME;
break;
case R.id.nav_history:
navItemIndex = 1;
CURRENT_TAG = TAG_HISTORY;
break;
case R.id.nav_location:
navItemIndex = 2;
CURRENT_TAG = TAG_LOCATION;
break;
case R.id.nav_developments:
navItemIndex = 3;
CURRENT_TAG = TAG_DEVELOPMENTS;
break;
case R.id.nav_donations:
navItemIndex = 4;
CURRENT_TAG = TAG_DONATIONS;
break;
case R.id.nav_resources:
navItemIndex = 5;
CURRENT_TAG = TAG_RESOURCES;
break;
case R.id.nav_feedback:
navItemIndex = 6;
CURRENT_TAG = TAG_FEEDBACK;
break;
case R.id.nav_contactus:
navItemIndex = 7;
CURRENT_TAG = TAG_CONTACTUS;
break;
default:
navItemIndex = 0;
}
//Checking if the item is in checked state or not, if not make it in checked state
if (menuItem.isChecked()) {
menuItem.setChecked(false);
} else {
menuItem.setChecked(true);
}
menuItem.setChecked(true);
loadHomeFragment();
return true;
}
});
// Adding Floating Action Button to bottom right of main view
}
private void loadHomeFragment() {
// if user select the current navigation menu again, don't do anything
// just close the navigation drawer
if (getSupportFragmentManager().findFragmentByTag(CURRENT_TAG) != null) {
mDrawerLayout.closeDrawers();
// show or hide the fab button
return;
}
// Sometimes, when fragment has huge data, screen seems hanging
// when switching between navigation menus
// So using runnable, the fragment is loaded with cross fade effect
// This effect can be seen in GMail app
Runnable mPendingRunnable = new Runnable() {
@Override
public void run() {
// update the main content by replacing fragments
Fragment fragment = getHomeFragment();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.viewpager, fragment, CURRENT_TAG);
fragmentTransaction.commitAllowingStateLoss();
}
};
// If mPendingRunnable is not null, then add to the message queue
if (mPendingRunnable != null) {
mHandler.post(mPendingRunnable);
}
// show or hide the fab button
//Closing drawer on item click
mDrawerLayout.closeDrawers();
}
private Fragment getHomeFragment() {
switch (navItemIndex) {
case 0:
// home
one_main oneMain = new one_main();
return oneMain;
case 1:
// photos
one_fragment oneFragment = new one_fragment();
return oneFragment;
case 2:
// movies fragment
two_location twoLocation = new two_location();
return twoLocation;
case 3:
// notifications fragment
four_future fourFuture = new four_future();
return fourFuture;
case 4:
// settings fragment
three_donation threeDonation = new three_donation();
return threeDonation;
case 5:
// movies fragment
six_download sixDownload = new six_download();
return sixDownload;
case 6:
// notifications fragment
five_feedback fiveFeedback = new five_feedback();
return fiveFeedback;
case 7:
// settings fragment
seven_contact sevenContact = new seven_contact();
return sevenContact;
default:
return new one_main();
}
}
我可以打开我的应用程序。 我能够在选项卡之间导航。 我能够拉出抽屉布局。 但是，当我单击抽屉中的任何项目时，会切换到相应的选项卡。但是选项卡中的所有内容都变空了。如何解决？
或者在Drawer Layout中点击item的fragment switching有什么更好的解决方案吗？如果是，请指出详细教程。
最佳答案
我使用下面的代码解决了这个问题:
viewPager.setCurrentItem(navItemIndex)
在navigationView.setNavigationItemSelectedListener中
关于android - 在抽屉导航中单击项目时在 viewpager 中切换 fragment ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43026175/