ViewPager 在单击时不响应选项卡

Question

我试图在我的活动中添加一个带有片段的选项卡，但它没有响应或事件显示。

下面是我的代码。

这是我的主要活动：

private void setupTabLayout() {
    TabLayout tabLayout = findViewById(R.id.tab_layout);
    tabLayout.addTab(tabLayout.newTab().setText("COMMENTS"));
    tabLayout.addTab(tabLayout.newTab().setText("ATTACHMENTS"));
    tabLayout.addTab(tabLayout.newTab().setText("AUDIT TRAIL"));
    tabLayout.addTab(tabLayout.newTab().setText("APPROVERS"));

    final ViewPager viewPager = findViewById(R.id.pager);
    final PagerAdapter adapter = new com.example.android.ontrack.adapters.PagerAdapter(getSupportFragmentManager(),tabLayout.getTabCount());
    viewPager.setAdapter(adapter);
    viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
    tabLayout.addOnTabSelectedListener(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) {

        }
    });
}



Here is my XML code:

 <android.support.v4.widget.NestedScrollView
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginBottom="@dimen/margin"
                android:fillViewport="true">

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <android.support.design.widget.TabLayout
                    android:id="@+id/tab_layout"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginBottom="@dimen/margin"
                    android:paddingLeft="@dimen/padding"
                    android:paddingRight="@dimen/padding"
                    android:background="@color/blue"
                    android:fillViewport="true"
                    app:tabMode="scrollable"
                    app:tabIndicatorColor="@android:color/white"
                    app:tabSelectedTextColor="@android:color/white"
                    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />

                    <android.support.v4.view.ViewPager
                        android:id="@+id/pager"
                        android:layout_width="match_parent"
                        android:layout_height="match_parent" />

            </RelativeLayout>

            </android.support.v4.widget.NestedScrollView>

这是我的 PagerAdapter：

public class PagerAdapter extends  FragmentStatePagerAdapter {
    int mNumOfTabs;

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

    @Override
    public Fragment getItem(int position) {

        switch (position) {
            case 0:
                CommentsFragment tab1 =  new CommentsFragment();
                return tab1;
            case 1:
                AttachmentsFragment tab2 = new AttachmentsFragment();
                return tab2;
            case 2:
                AuditTrailFragment tab3 = new AuditTrailFragment();
                return tab3;
            case 3:
                ApproversFragment tab4 = new ApproversFragment();
                return tab4;
            default:
                return null;
        }
    }

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

Answer 1

From Docs

您只需拨打tabLayout.setupWithViewPager(viewPager);

XML 中似乎存在问题，你 TabLayout 应该在 ViewPager 内

因为

viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

意味着您要更改选项卡并且每个选项卡都托管一个片段。

更新：您已删除添加选项卡的代码，如 github 链接所示，发布在 cmets 中。

// add these lines again
TabLayout tabLayout = findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText("COMMENTS"));
tabLayout.addTab(tabLayout.newTab().setText("ATTACHMENTS"));
tabLayout.addTab(tabLayout.newTab().setText("AUDIT TRAIL"));
tabLayout.addTab(tabLayout.newTab().setText("APPROVERS"));
ViewPager viewPager = (ViewPager)findViewById(R.id.viewPager);
viewPager.setAdapter(new CustomFragmentPagerAdapter(getSupportFragmentManager()));
viewPager.setCurrentItem(2);
tabLayout.setupWithViewPager(viewPager);
//... code of listener etc

Answer 2

这是我的示例。它应该工作。 https://github.com/ElifBon/FragmentAdapterProject

xml：

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

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

    <ViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"></ViewPager>
</LinearLayout>

您的活动：

 TabLayout tabLayout = (TabLayout)findViewById(R.id.tabLayout);
 ViewPager viewPager = (ViewPager)findViewById(R.id.viewPager);
 viewPager.setAdapter(new CustomFragmentPagerAdapter(getSupportFragmentManager()));
 viewPager.setCurrentItem(2);
 tabLayout.setupWithViewPager(viewPager);

 tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
     @Override
     public void onTabSelected(TabLayout.Tab tab) {
         // TODO : Something
     }

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

     }

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

     }
 });

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

    }

    @Override
    public void onPageSelected(int position) {
        // TODO : Something
    }

    @Override
    public void onPageScrollStateChanged(int state) {

    }
});

适配器：

private class CustomFragmentPagerAdapter extends FragmentPagerAdapter{

Fragment1 fragment1;
Fragment2 fragment2;
Fragment3 fragment3;

    public  CustomFragmentPagerAdapter(android.support.v4.app.FragmentManager fm){
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        if(position == 0){
            if(fragment1 == null){
                fragment1 = Fragment1.getInstance();
            }
            return  fragment1;
        }else if(position == 1){
            if(fragment2 == null){
                fragment2 = Fragment2.getInstance();
            }
            return fragment2;
        }else if(position == 2){
            if(fragment3 == null){
                fragment3 = Fragment3.getInstance();
            }
            return fragment3;
        }else{
            return null;
        }
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return "Title - " + String.valueOf(position);
    }

    @Override
    public int getCount() {
        return 3;
    }
}