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

问题描述

所以我试图在我的主要导航栏下方设置一个标签栏和布局来处理我的主要活动.

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

我似乎无法让 ViewPager/TabLayout(不确定哪个是问题的原因，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 1 个以上的教程，以查看我是否正确地执行此操作，并且似乎我正在做与他们相同的事情...

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 看到选项卡正确更改，并且在 OnTabSelected 我调用 viewPager.setCurrentItem(tab.getPosition()) 尝试设置我的 viewpagers 项目，但它仍然无法正常工作.第一次加载时，它加载第一个和第二个选项卡(我可以通过片段 onCreate 方法发送的 API 请求看到)，当我单击其他选项卡时，它始终加载错误的片段，有时甚至根本不加载！

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!

不确定这是否相关，但我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:BlankFragment3 的片段状态{efddbec #2 id=0x7f0c007b android:switcher:218714292 未更新排队;预期状态 3 找到 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>

根据多个教程，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);
}

如果有人发现这有什么问题，请告诉我，我这辈子都无法让这些该死的标签加载正确的片段.

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.

提前致谢！

推荐答案

试试这个代码伙伴 :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;
      } 
   }

以及我在 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) {

        }
    });

希望你能解决你的问题:)

hope you can solve your issue :)

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