Viewpager 片段中的 Textview 无法正确更新

Question

我创建了一个布局，并根据收到的数据动态添加选项卡。我对动态更新文本视图的片段做同样的事情。虽然当布局加载时，如果我浏览片段或查看寻呼机（对不起，我对所有这些都不熟悉，希望我的术语是正确的）它们更新得很好（这意味着更新有时会出现延迟，问题不大）并且正确数据。虽然，如果在新鲜的情况下我打开布局并单击选项卡以更改我的片段，我没有得到数据或错误的数据。 示例：- 第一次加载布局时，我的第一个和第三个标签加载正常。如果我单击第二个选项卡（不是滑动而是一直触摸顶部的选项卡），我的第二个选项卡的片段中没有任何数据。在这里和那里随机选择选项卡时，第一个选项卡会加载第二个选项卡数据，但第二个选项卡从不加载任何内容。如果我加载新页面或第一次滑动，它就不一样了。 让我知道我在哪里做错了。谢谢。

这是我的代码：-

布局文件 - show_score.xml

<android.support.design.widget.CoordinatorLayout 
    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"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.lp.activity.ShowScorePassagesActivity">
    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/children_school"
        android:scaleType="centerCrop"
        android:alpha="0.5"
        android:layout_below="@+id/appBackBar"/>

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/appbar_padding_top"
        android:theme="@style/AppTheme.AppBarOverlay">

        <include android:id="@+id/appBackBar"
            layout="@layout/detail_appbar"/>

        <android.support.design.widget.TabLayout
            android:id="@+id/passagetabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

        </android.support.design.widget.TabLayout>
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</android.support.design.widget.CoordinatorLayout>

片段文件 - fragment_show_score_passage.xml

   <android.support.constraint.ConstraintLayout 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"
    android:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.lp.activity.ShowScorePassagesActivity$PlaceholderFragment">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <!-- TODO: Update blank fragment layout -->
        <android.support.v7.widget.CardView
            android:id="@+id/cardView4"
            android:layout_width="match_parent"
            android:layout_height="200dp"
            app:cardElevation="5dp"
            android:scaleType="fitXY"
            android:layout_margin="5dp">
            <ScrollView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                style="@style/scrollbar_shape_style">
                <TextView
                    android:id="@+id/showScore"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:textSize="18dp"
                    android:scaleType="fitXY"
                    android:text="TextView"
                    android:autoLink="web"
                    android:linksClickable="true"
                    android:padding="20dp"
                    android:clipToPadding="false"/>
            </ScrollView>
        </android.support.v7.widget.CardView>

        <android.support.v7.widget.CardView
            android:id="@+id/cardView5"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:cardElevation="5dp"
            android:layout_below="@+id/cardView4"
            android:layout_marginLeft="5dp"
            android:layout_marginRight="5dp"
            android:layout_marginTop="5dp">
            <ScrollView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                style="@style/scrollbar_shape_style">
                <GridView
                    android:id="@+id/fluencyAudioGrid"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:numColumns="auto_fit"
                    android:horizontalSpacing="2dp"
                    android:verticalSpacing="5dp"
                    android:columnWidth="120dp"
                    android:paddingTop="10dp"
                    android:paddingBottom="10dp"
                    android:clipToPadding="false"
                    android:stretchMode="spacingWidthUniform"
                    layout="@layout/icons_for_dashboard"
                    android:scrollbarThumbVertical="@drawable/scroolbar_style"
          android:scrollbarTrackVertical="@drawable/scroolbar_style_background">
                </GridView>
            </ScrollView>
        </android.support.v7.widget.CardView>
    </RelativeLayout>

</android.support.constraint.ConstraintLayout>

还有发生魔法的主要 Java 文件 - ShowScorePassageActivity.java

    public class ShowScorePassagesActivity extends AppCompatActivity {

    private SectionsPagerAdapter mSectionsPagerAdapter;
    private ViewPager mViewPager;
    public GridView gridView;
    public ArrayList<String> gridItems = new ArrayList<String>();
    public static TextView fragTextView;
    static String fragNewTextView = "";
    public static ArrayList<String> fluencyMarksList = new ArrayList<>();
    public TabLayout tabLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.show_score_passages);

        Intent in = getIntent();
        String intentData = in.getStringExtra("intentData");
        String fluencyMarks = in.getStringExtra("fluencyMarks");
        tabLayout = (TabLayout) findViewById(R.id.passagetabs);
        String mFluencyMarkList []= fluencyMarks.split("@");
        fluencyMarksList = new ArrayList<String>(Arrays.asList(mFluencyMarkList));
        int count = 1;
        int counts=fluencyMarksList.size();
        for(int i = 0; i < counts; i++){
            tabLayout.addTab(tabLayout.newTab().setText("Passage "+count));
            count=count+1;
        }
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
        mViewPager = (ViewPager) findViewById(R.id.container);
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
        mViewPager.setAdapter(mSectionsPagerAdapter);
        mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                mViewPager.setCurrentItem(tab.getPosition());
                int position =  tab.getPosition();
                if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {
                    if (position ==0){
                        fragTextView.setText(Html.fromHtml(fluencyMarksList.get(0), Html.FROM_HTML_MODE_COMPACT));
                    }
                    else if (position ==1){
                        fragTextView.setText(Html.fromHtml(fluencyMarksList.get(1) , Html.FROM_HTML_MODE_COMPACT));
                    }
                    else if (position ==2){
                        fragTextView.setText(Html.fromHtml(fluencyMarksList.get(2) , Html.FROM_HTML_MODE_COMPACT));
                    }
                } else {
                    if (position ==0){
                        fragTextView.setText(Html.fromHtml(fluencyMarksList.get(0)));
                    }
                    else if (position ==1){
                        fragTextView.setText(Html.fromHtml(fluencyMarksList.get(1)));
                    }
                    else if (position ==2){
                        fragTextView.setText(Html.fromHtml(fluencyMarksList.get(2)));
                    }
                }
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) {
                fragTextView.setText("");
            }
            @Override
            public void onTabReselected(TabLayout.Tab tab) {
            }
        });
    }
    @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_show_score_passages, 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();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";

        public PlaceholderFragment() {
        }

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }
        @RequiresApi(api = Build.VERSION_CODES.N)
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_show_score_passages, container, false);
            fragTextView = (TextView) rootView.findViewById(R.id.showScore);
            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {

                fragTextView.setText(Html.fromHtml(fluencyMarksList.get(0) , Html.FROM_HTML_MODE_COMPACT));
            } else {

                fragTextView.setText(Html.fromHtml(fluencyMarksList.get(0)));
            }
            return rootView;
        }
        @Override
        public void onActivityCreated(Bundle savedInstanceState) {
            super.onActivityCreated(savedInstanceState);
        }
    }
    public class SectionsPagerAdapter extends FragmentPagerAdapter {
        int mNumOfTabs;
        Fragment fragment = null;

        public SectionsPagerAdapter(FragmentManager fm, int NumOfTabs) {
            super(fm);
            this.mNumOfTabs=NumOfTabs;

        }

        @Override
        public Fragment getItem(int position) {
            return PlaceholderFragment.newInstance(position + 1);
        }

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

Answer 1

这就是我所做的：

这只是对我有用的一个例子，希望能帮助你

在OnCreate:

ViewPager mViewPager = (ViewPager) findViewById(R.id.container);
this.addPages(mViewPager);
mViewPager.setOffscreenPageLimit(3);

TabLayout tabLayout = (TabLayout) findViewById(R.id.mTab_ID);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
tabLayout.setupWithViewPager(mViewPager);
tabLayout.addOnTabSelectedListener(listener(mViewPager));

然后通过执行以下操作将片段添加到TabLayout：

//ADD ALL PAGES TO TABLAYOUT
private void addPages(ViewPager pager) {
    adapter = new MyFragPagerAdapter(getSupportFragmentManager());
    adapter.addPage(new FragmentAdapter1());
    adapter.addPage(new FragmentAdapter2());
    adapter.addPage(new FragmentAdapter3());

    //SET ADAPTER TO PAGER
    pager.setAdapter(adapter);
}

然后实现TabLayout点击事件OnTabSelectedListener做：

//TabLayout Click Events
private TabLayout.OnTabSelectedListener listener(final ViewPager pager) {
    return new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            pager.setCurrentItem(tab.getPosition());
        }

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

        }

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

        }
    };
}