MVVM：在具有导航视图的视图寻呼机中出现片段重叠问题？

概述当我从导航视图的菜单之间切换时,我面临片段重叠的问题..最初,我的应用程序具有带有多个选项的导航视图..在该主页选项片段中,视图分页器包含两个选项卡..当我在视图分页器选项卡之间切换时效果很好..问题是,当我从导航菜单(如“设置”)切换菜单时,相应的片段加载良好,然后我重新

当我从导航视图的菜单之间切换时,我面临片段重叠的问题..最初,我的应用程序具有带有多个选项的导航视图..在该主页选项片段中,视图分页器包含两个选项卡..当我在视图分页器选项卡之间切换时效果很好..

问题是,当我从导航菜单(如“设置”)切换菜单时,相应的片段加载良好,然后我重新加载了首页片段,视图分页器加载了选项卡,但是旧片段(设置)显示在背景中

另外,当我加载几次home选项时,片段会重叠几次,而不是替换Fragment

我的代码如下

活动类：DashboardActivity.java

/** *   DashboardActivity.java */public class DashboardActivity extends AppCompatActivity        implements NavigationVIEw.OnNavigationItemSelectedListener, FragmentManager.OnBackStackChangedListener,        VIEwPagelistener {    /**     * Used as initializing the layout as data binding.     */    private ActivityDashboardBinding activityDashboardBinding;    @OverrIDe    protected voID onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        activityDashboardBinding = DataBindingUtil.setContentVIEw(this, R.layout.activity_dashboard);        activityDashboardBinding.setonClickController(new DashboardController());        setSupportActionbar(activityDashboardBinding.toolbar);        getSupportActionbar().setdisplayShowTitleEnabled(false);        ActionbarDrawerToggle toggle = new ActionbarDrawerToggle(                this, activityDashboardBinding.drawerLayout, activityDashboardBinding.toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);        activityDashboardBinding.drawerLayout.addDrawerListener(toggle);        activityDashboardBinding.navigationVIEw.setNavigationItemSelectedListener(this);        toggle.syncState();        getSupportActionbar().setdisplayHomeAsUpEnabled(true);        getSupportActionbar().setDefaultdisplayHomeAsUpEnabled(false);        toggle.setDrawerIndicatorEnabled(false);        toggle.setHomeAsUpIndicator(R.drawable.ic_menu_hamburger);        toggle.setToolbarNavigationClickListener(new VIEw.OnClickListener() {            @OverrIDe            public voID onClick(VIEw vIEw) {                if (activityDashboardBinding.drawerLayout.isDrawerOpen(GravityCompat.START)) {                    activityDashboardBinding.drawerLayout.closeDrawer(GravityCompat.START);                } else {                    activityDashboardBinding.drawerLayout.openDrawer(GravityCompat.START);                }            }        });        displaySelectedScreen(R.ID.nav_home);    }    @OverrIDe    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.menu_dashboard, menu);        return true;    }    @OverrIDe    public boolean onoptionsItemSelected(MenuItem item) {        // Handle action bar item clicks here. The action bar will        // automatically handle clicks on the Home/Up button, so long        // as you specify a parent activity in AndroIDManifest.xml.        int ID = item.getItemID();        if (ID == R.ID.action_notification) {            startActivity(new Intent(this, NotificationActivity.class));            return true;        }        return super.onoptionsItemSelected(item);    }    @SuppressWarnings("StatementWithEmptyBody")    @OverrIDe    public boolean onNavigationItemSelected(@NonNull MenuItem item) {        // Handle navigation vIEw item clicks here.        displaySelectedScreen(item.getItemID());        return true;    }    /**     * Method used as navigation selection option.     *     * @param itemID Selected  ID.     */    private voID displaySelectedScreen(int itemID) {        Fragment fragment = null;        String fragmentname = null;        if (itemID == R.ID.nav_home) {            activityDashboardBinding.toolbarTitle.setText(R.string.toolbar_name_dashboard);            activityDashboardBinding.addNewRIDe.show();            fragment = new HomePageFragment();            fragmentname = Constants.name_NAVIGATION_DASHBOARD;        } else if (itemID == R.ID.nav_rIDes) {        } else if (itemID == R.ID.nav_profile) {            activityDashboardBinding.toolbarTitle.setText(R.string.toolbar_name_my_profile);            activityDashboardBinding.addNewRIDe.hIDe();            fragment = new UserProfileFragment();            fragmentname = Constants.name_NAVIGATION_MY_PROfile;        } else if (itemID == R.ID.nav_settings) {            activityDashboardBinding.toolbarTitle.setText(R.string.toolbar_name_settings);            fragment = new SettingsFragment();            activityDashboardBinding.addNewRIDe.hIDe();            fragmentname = Constants.name_NAVIGATION_SETTINGS;        } else if (itemID == R.ID.nav_logout) {            Intent logoutIntent = new Intent(getApplicationContext(), LoginActivity.class);            logoutIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);            startActivity(logoutIntent);        }        if (fragment != null) {            FragmentManager fragmentManager = getSupportFragmentManager();            fragmentManager.addOnBackStackChangedListener(this);            fragmentManager.beginTransaction().add(R.ID.container, fragment)                    .addToBackStack(fragmentname).commit();        }        DrawerLayout drawer = (DrawerLayout) findVIEwByID(R.ID.drawer_layout);        drawer.closeDrawer(GravityCompat.START);    }    @OverrIDe    public voID onBackpressed() {        if (activityDashboardBinding.drawerLayout.isDrawerOpen(GravityCompat.START)) {            activityDashboardBinding.drawerLayout.closeDrawer(GravityCompat.START);        } else if (getFragmentname().equals(Constants.name_NAVIGATION_DASHBOARD)) {            finish();        } else {            // Let super handle the back press            super.onBackpressed();        }    }    @OverrIDe    public voID onBackStackChanged() {        if (getFragmentname().equals(Constants.name_NAVIGATION_DASHBOARD)) {            activityDashboardBinding.toolbarTitle.setText(R.string.toolbar_name_dashboard);            activityDashboardBinding.addNewRIDe.show();        } else if (getFragmentname().equals(Constants.name_NAVIGATION_MY_PROfile)) {            activityDashboardBinding.toolbarTitle.setText(R.string.toolbar_name_my_profile);            activityDashboardBinding.addNewRIDe.hIDe();        } else {            activityDashboardBinding.toolbarTitle.setText(R.string.toolbar_name_settings);            activityDashboardBinding.addNewRIDe.hIDe();        }    }    /**     * Method used to get the fragment transaction name to IDentify the fragment.     *     * @return the fragment name.     */    private String getFragmentname() {        FragmentManager fm = getSupportFragmentManager();        return fm.getBackStackEntryAt(fm.getBackStackEntryCount() - 1).getname();    }    @OverrIDe    public voID onVIEwPagelistener() {        activityDashboardBinding.addNewRIDe.animate().translationY(0).setInterpolator(new linearInterpolator()).start();    }}

DashboardVIEwAdapter.java

/** * The class that contains the List of fragments and List of Title. We can use the fragments using * vIEw pager from here. * * @version 1.0 */public class DashboardVIEwAdapter extends FragmentStatePagerAdapter {    /**     * Title of the fragment List.     */    private String[] mTitle;    /**     * Fragment List Which contains the fragments on the adapter.     */    private List<Fragment> fragmentList;    /**     * Instantiates a new adapter dashboard vIEw.     *     * @param fm the Instance of the FragmentManager.     */    public DashboardVIEwAdapter(FragmentManager fm) {        super(fm);    }    /**     * Set the List of Title from the activity.     *     * @param Titles Title List.     */    public voID setTitle(String[] Titles) {        this.mTitle = Titles;    }    /**     * Set the fragment List for the particular vIEw pager using FragmentStatePagerAdapter.     *     * @param fragmentList List of fragment.     */    public voID setFragmentList(List<Fragment> fragmentList) {        this.fragmentList = fragmentList;    }    @OverrIDe    public Fragment getItem(int position) {        return fragmentList.get(position);    }    @OverrIDe    public int getCount() {        return mTitle.length;    }    @OverrIDe    public CharSequence getPageTitle(int position) {        return mTitle[position];    }}

HomePageFragment.java

/** * Fragment used as home page to display the rIDe offered and my rIDes details. * * @version 1.0 */public class HomePageFragment extends Fragment implements VIEwPager.OnPagechangelistener {    /**     * Binding the fragment.     */    private FragmentHomePageBinding homePageBinding;    /**     * Interface to Listen the vIEw pager changes.     */    private VIEwPagelistener vIEwPagelistener;    @OverrIDe    public VIEw onCreateVIEw(LayoutInflater inflater, VIEwGroup container,                             Bundle savedInstanceState) {        homePageBinding = DataBindingUtil.inflate(inflater, R.layout.fragment_home_page, container, false);        setTabs();        setHasOptionsMenu(true);        vIEwPagelistener = (VIEwPagelistener) getActivity();        return homePageBinding.getRoot();    }    /**     * Set up the RIDe offers and My rIDes fragments in the tab     */    private voID setTabs() {        String[] mTitle = new String[]{"RIDes offered", "My RIDes"};        FragmentManager fm = getChildFragmentManager();        DashboardVIEwAdapter mAdapter = new DashboardVIEwAdapter(fm);        mAdapter.setTitle(mTitle);        mAdapter.setFragmentList(getFragmentList());        homePageBinding.vIEwPager.setAdapter(mAdapter);        homePageBinding.tabLayout.setupWithVIEwPager(homePageBinding.vIEwPager);        homePageBinding.vIEwPager.addOnPagechangelistener(this);    }    /**     * Get the fragment List to display the vIEw pager tabs. Recent chat and contacts fragment will     * be return from this.     *     * @return List of the fragments for the vIEwpager     */    private List<Fragment> getFragmentList() {        /**         * Add the fragment as a List.         */        List<Fragment> fragmentList = new ArrayList<>();        /**         The fragment contacts which contains the rIDe offer List.         */        RIDesOfferedFragment rIDesOfferedFragment = new RIDesOfferedFragment();        /**         The fragment contacts which contains the rIDe offer List.         */        MyRIDesFragment myRIDesFragment = new MyRIDesFragment();        fragmentList.add(rIDesOfferedFragment);        fragmentList.add(myRIDesFragment);        return fragmentList;    }    @OverrIDe    public voID onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {        vIEwPagelistener.onVIEwPagelistener();    }    @OverrIDe    public voID onPageSelected(int position) {        //OverrIDden Method    }    @OverrIDe    public voID onPageScrollStateChanged(int state) {        //OverrIDden Method    }    @OverrIDe    public voID onPrepareOptionsMenu(Menu menu) {        menu.findItem(R.ID.action_notification).setVisible(true);        super.onPrepareOptionsMenu(menu);    }}

activity_dashboard.xml

<?xml version="1.0" enCoding="utf-8"?><layout 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">    <data>        <variable            name="onClickController"            type="com.contus.carpooling.dashboard.homepage.viewmodel.DashboardController" />    </data>    <androID.support.v4.Widget.DrawerLayout        androID:ID="@+ID/drawer_layout"        androID:layout_wIDth="match_parent"        androID:layout_height="match_parent"        androID:fitsSystemwindows="true"        tools:openDrawer="start">        <androID.support.design.Widget.CoordinatorLayout            androID:ID="@+ID/coordinator_layout"            androID:layout_wIDth="match_parent"            androID:layout_height="match_parent"            androID:fitsSystemwindows="true"            tools:context="com.contus.carpooling.dashboard.homepage.vIEw.DashboardActivity">            <linearLayout                androID:layout_wIDth="match_parent"                androID:layout_height="match_parent"                androID:orIEntation="vertical">                <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/Apptheme.PopupOverlay">                    <TextVIEw                        androID:ID="@+ID/tool_bar_Title"                        androID:layout_wIDth="wrap_content"                        androID:layout_height="wrap_content"                        androID:layout_gravity="center"                        androID:text="Dashboard"                        androID:textcolor="@androID:color/white"                        androID:textSize="18sp" />                </androID.support.v7.Widget.Toolbar>                <FrameLayout                    androID:ID="@+ID/container"                    androID:layout_wIDth="match_parent"                    androID:layout_height="match_parent"                    app:layout_behavior="@string/appbar_scrolling_vIEw_behavior" />            </linearLayout>            <androID.support.design.Widget.floatingActionbutton                androID:ID="@+ID/add_new_rIDe"                androID:layout_wIDth="wrap_content"                androID:layout_height="wrap_content"                androID:layout_gravity="right|bottom"                androID:layout_margin="10dp"                androID:clickable="true"                androID:onClick="@{onClickController.fabBtnOnClick()}"                androID:src="@drawable/ic_action_add"                app:backgroundTint="@color/colorSecondarycolor"                app:fabSize="normal"                app:layout_behavior="com.contus.carpooling.vIEw.ScrollAwareFABBehavior" />        </androID.support.design.Widget.CoordinatorLayout>        <androID.support.design.Widget.NavigationVIEw            androID:ID="@+ID/navigation_vIEw"            androID:layout_wIDth="wrap_content"            androID:layout_height="match_parent"            androID:layout_gravity="start"            androID:background="@androID:color/white"            androID:fitsSystemwindows="true"            app:headerLayout="@layout/navigation_header"            app:itemIconTint="@color/colorPrimary"            app:itemTextcolor="#4b4b4b"            app:menu="@menu/activity_dashboard_drawer"            app:theme="@style/NavigationDrawerSelected" />    </androID.support.v4.Widget.DrawerLayout></layout>

fragment_home_page.xml

<layout 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">    <data /><FrameLayout    androID:layout_wIDth="match_parent"    androID:layout_height="match_parent">    <linearLayout        androID:layout_wIDth="match_parent"        androID:layout_height="match_parent"        androID:orIEntation="vertical"        tools:context="com.contus.carpooling.dashboard.homepage.vIEw.HomePageFragment">        <androID.support.design.Widget.TabLayout            androID:ID="@+ID/tab_layout"            androID:layout_wIDth="match_parent"            androID:layout_height="wrap_content"            androID:background="@color/colorPrimary"            androID:minHeight="?attr/actionbarSize"            androID:theme="@style/themeOverlay.AppCompat.Dark.Actionbar"            app:tabIndicatorcolor="@color/colorHighlightBlue"            app:tabIndicatorHeight="4dp" />        <androID.support.v4.vIEw.VIEwPager            androID:ID="@+ID/vIEw_pager"            androID:layout_wIDth="match_parent"            androID:layout_height="match_parent"            app:layout_behavior="@string/appbar_scrolling_vIEw_behavior" />    </linearLayout></FrameLayout></layout>

设置显示在仪表板的背景中.

等待回应…预先致谢

解决方法:

在这里,问题是添加了将背景设为透明的片段,因此将背景设置为布局片段文件
例如：

    <FrameLayoutandroID:layout_wIDth="match_parent"androID:layout_height="match_parent"androID:background="@color/colorBackground">

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