标签文本随viewpager消失

Question

一个非常简单的例子.我想大多数人都是以这种方式实现一个标签.但标签文本只是缺失.

设计支持lib的版本是最新的24.2.0.

这是我的布局代码:

<android.support.design.widget.TabLayout
    android:id="@+id/tabs"
    app:tabTextColor="@android:color/darker_gray"
    app:tabSelectedTextColor="@android:color/white"
    android:background="@color/colorPrimary"
    android:minHeight="?attr/actionBarSize"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <android.support.design.widget.TabItem
        android:text="@string/tab_domain"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <android.support.design.widget.TabItem
        android:text="@string/tab_upload"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <android.support.design.widget.TabItem
        android:text="@string/tab_download"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

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

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

我正在使用ButterKnife 8.2.1来绑定视图对象.这是我在onCreate()中的活动代码:

    final DiagnosePagerAdapter adapter = new DiagnosePagerAdapter(getSupportFragmentManager(),
            tabs.getTabCount());
    tabs.setupWithViewPager(pager);
    pager.setAdapter(adapter);
    pager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabs));

这是我的适配器:

    class DiagnosePagerAdapter extends FragmentStatePagerAdapter {
    int mNumOfTabs;
    List<Fragment> fragments = new ArrayList<>();

    public DiagnosePagerAdapter(FragmentManager fm, int numberOfTabs) {
        super(fm);
        this.mNumOfTabs = numberOfTabs;
        fragments.add(new DomainFragment());
        fragments.add(new UploadFragment());
        fragments.add(new DownloadFragment());
    }

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

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

我在这里看到了类似的问题:在Fragment中使用TabLayout; 标签文字不可见

该问题的答案说这已在23.0.0中修复,并且我的手机上没有任何解决方法,包括小米HM 2A和华为设备.

Answer 1

您必须覆盖getPageTitle()如下(我认为这将解决您的问题):

@Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return "Domain";
            case 1:
                return "Upload";
            case 2:
                return "Download";
        }
        return null;
    }

此外,由于您有固定数量的选项卡,您应该使用FragmentPagerAdapter而不是FragmentStatePagerAdapter.然后更改您的xml布局如下:

<android.support.design.widget.TabLayout
    android:id="@+id/tabs"
    app:tabTextColor="@android:color/darker_gray"
    app:tabSelectedTextColor="@android:color/white"
    android:background="@color/colorPrimary"
    android:minHeight="?attr/actionBarSize"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

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

更改您的适配器如下:

class DiagnosePagerAdapter extends FragmentPagerAdapter {

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

    @Override
    public Fragment getItem(int position) {
        Fragment fragment = null;
        switch (position) {
            case 0:
                fragment = new DomainFragment();
                break;
            case 1:
                fragment = new UploadFragment();
                break;
            case 2:
                fragment = new DownloadFragment();
                break;
        }
        return fragment;
    }

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

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return "Domain";
            case 1:
                return "Upload";
            case 2:
                return "Download";
        }
        return null;
    }

}

并改变你的onCreate()如下:

final DiagnosePagerAdapter adapter = new DiagnosePagerAdapter(getSupportFragmentManager());
pager.setAdapter(adapter);//call setAdapter() before setupWithViewPager()
tabs.setupWithViewPager(pager);