【发布时间】：2017-03-26 07:23:56
【问题描述】：
即使在 Stack Overflow 上看到很多问题后，我也没有得到正确的答案，因此写了这篇文章。我在 View Pager 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>
我是从 Google Code Lab Material Design 编写的。我的基本要求：
视图分页器中有六个选项卡或片段。拉动导航抽屉时也会出现相应的六个选项。当我单击抽屉中的项目时说项目编号 4，从当前选项卡或片段到相应的第 4 个选项卡或片段必须有一个沼泽。
我的主要活动中的代码：
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为空。如何解决？
或者对于在抽屉布局中单击的项目进行片段切换有更好的解决方案吗？如果是，请指出详细的教程。
【问题讨论】：
-
我理解迈克的问题。我是材料设计的初学者。你能帮我更新代码吗？那真的很有帮助
-
我尝试使用本教程 androidhive.info/2013/11/… 进行编码。但是，在我单击抽屉中的任何项目（例如第 4 个项目）的情况下，它会转到第四个片段或选项卡，但该选项卡中的所有内容都保持为空。相邻的两到三个选项卡也会变为空。
-
迈克问题解决了。请把你的评论作为答案。我会接受的。只是另一件事，即使在下面的代码中，我是否应该像之前所做的那样 replce loadHomeFragment？
-
public void onBackPressed() { // 此代码在按下返回键时加载主页片段 // 当用户位于主页以外的其他片段时 if (shouldLoadHomeFragOnBackPress) { // 检查用户是否在其他导航上menu // 而不是 home if (navItemIndex != 0) { navItemIndex = 0; CURRENT_TAG = TAG_HOME； loadHomeFragment();返回; } } super.onBackPressed(); }
-
我还面临另一个问题。如您所知，在选项卡布局中，应用程序的名称显示在顶部。例如在下图中androidhive.info/wp-content/uploads/2015/09/…，它的客户视图图标和文本。有时当我导航到不同的片段时，这个应用程序名称会消失，只有我看到标签标题。为什么会出现这个问题？
标签： android android-layout android-fragments tabs navigation-drawer