Android ViewPager加载不正确的片段 [英] Android ViewPager Loading incorrect fragments

问题描述

因此，我正在尝试在主导航栏下面获取一个标签栏和布局，以进行主要活动.

So I'm trying to get a tab bar and layout underneath my main navigation bar working on my main activity.

我似乎无法获得ViewPager/TabLayout(不确定这是问题的原因，这是新的)来加载正确的片段.我已经阅读了大量文档，并检查了不止一个教程，以查看我是否正确地执行了此操作，并且看来我正在做的事情与它们相同...

I can't seem to get the ViewPager/TabLayout (unsure which is the cause of the problem, new to this) to load the correct fragment. I've read through a ton of documentation and checked more than 1 tutorial to see if I was doing this correctly and it seems that I'm doing the same thing they are...

我的TabLayout的OnTabSelectedListener看到选项卡已正确更改，并且在OnTabSelected中，我正在调用viewPager.setCurrentItem(tab.getPosition())尝试设置我的viewpagers项，但它仍然无法正常工作.第一次加载时，它会加载第一个和第二个选项卡(我可以通过onCreate方法中的片段通过已发送的API请求看到)，并且当我单击其他选项卡时，它始终会加载错误的片段，有时甚至根本不会加载一个片段！

The OnTabSelectedListener for my TabLayout is seeing the tab changes properly, and in OnTabSelected Im calling viewPager.setCurrentItem(tab.getPosition()) to attempt to set my viewpagers item, but it's still not working. Upon first load, it loads the first and second tabs (I can see via a sent API request from the fragments onCreate methods), and when I click on the other tabs, it consistently loads the wrong fragment, sometimes not even loading one at all!

不确定是否与此相关，但是在切换标签页时收到此警告:

Not sure if this is related but I'm getting this warning as I switch tabs:

03-03 16:24:22.940 16967-16967/com.sampleapp.app W/FragmentManager: moveToState: Fragment state for BlankFragment3{efddbec #2 id=0x7f0c007b android:switcher:2131492987:2} not updated inline; expected state 3 found 2

我正在使用构建工具版本23.0.2和以下依赖项:

I'm using build tools version 23.0.2 and the following dependencies:

compile 'com.android.support:appcompat-v7:23.1.1'
compile 'com.android.support:design:23.1.1'
compile 'com.android.support:support-v4:23.1.1'

这是我的主导航栏的布局代码:

This is my layout code for my main nav bar:

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar1"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:popupTheme="@style/AppTheme.PopupOverlay" />

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar2"
        android:layout_width="match_parent"
        android:layout_height="10dp"
        android:background="?attr/colorPrimary"
        app:layout_scrollFlags="scroll|enterAlways"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

    <android.support.design.widget.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabMode="fixed"
        app:tabGravity="fill"/>

</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.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="@dimen/fab_margin"
    android:src="@android:drawable/ic_input_add" />

</android.support.design.widget.CoordinatorLayout>

根据不止一个教程，这是我用于适配器的代码

As per more than one tutorial, here is the code I'm using for my adapter

public class TabsAdapter extends FragmentPagerAdapter{
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public TabsAdapter(FragmentManager fm) {
        super(fm);
    }

    public void addFrag(Fragment fragment, String title){
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
}

这是我设置Viewpager和TabLayout的方法

And here is how I set up my viewpager and tablayout

MainActivity的onCreate:

MainActivity's onCreate:

    ViewPager = (ViewPager) findViewById(R.id.viewpager);
    setupViewPager(mViewPager); // Method defined below

    TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
    tabLayout.setupWithViewPager(mViewPager);
    tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            mViewPager.setCurrentItem(tab.getPosition());
            Log.w("Tab Selection", String.valueOf(tab.getPosition()));
        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {

        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {

        }
    });

最后，我的setupViewPager方法:

And finally, my setupViewPager method:

private void setupViewPager(ViewPager viewPager) {
    TabsAdapter adapter = new TabsAdapter(getSupportFragmentManager());
    adapter.addFrag(new BlankFragment1(), "One");
    adapter.addFrag(new BlankFragment2(), "Two");
    adapter.addFrag(new BlankFragment3(), "Three");
    viewPager.setAdapter(adapter);
}

如果有人发现任何问题，请告诉我，我一生都无法获得这些darn标签来加载适当的片段.

If anyone sees anything wrong with this please let me know, I cannot for the life of me get these darn tabs to load the proper fragment.

提前谢谢！

推荐答案

尝试使用此代码伴侣:D

Try with this code mate :D

ViewPager适配器

ViewPager adapter

public class PageAdapter extends FragmentStatePagerAdapter {
int mNumOfTabs;

public PageAdapter(FragmentManager fm,int numTabs) {
    super(fm);
    this.mNumOfTabs = numTabs;
}

@Override
public Fragment getItem(int position) {
    switch (position) {
        case 0:
            RemindsTab remindsTab = new RemindsTab();
            return remindsTab;
        case 1:
            TasksTab tasksTab = new TasksTab();
            return tasksTab;
        case 2:
            QuicklyNotesTab quicklyNotesTab = new QuicklyNotesTab();
            return quicklyNotesTab;
        default:
            return null;
    }
}

@Override
public int getCount() {
    return mNumOfTabs;
      } 
   }

和我在 MainActivity 中针对这些标签的代码:

and my code in MainActivity for those tabs:

 final TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
    tabLayout.addTab(tabLayout.newTab().setText("Recordatorios"));
    tabLayout.addTab(tabLayout.newTab().setText("Tareas"));
    tabLayout.addTab(tabLayout.newTab().setText("Notas Rapidas"));
    tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);

     final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
     final PagerAdapter adapter = new PageAdapter(getSupportFragmentManager(),tabLayout.getTabCount());
     viewPager.setAdapter(adapter);
     viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
    tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            viewPager.setCurrentItem(tab.getPosition());
        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {

        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {

        }
    });

希望您能解决您的问题:)

hope you can solve your issue :)

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