viewPager嵌套fragmen通用adapter

viewPager嵌套fragment很常用，來一個封裝好的通用adapter。

先建立一個FragmentInstancePagerAdapter，代碼如下：

import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentManager
import androidx.fragment.app.FragmentStatePagerAdapter

/**
 * 為每個類型 Fragment 都隻出現一個的 ViewPager 準備的 Adapter
 *
 * @author 
 * @date 
 */
class FragmentInstancePagerAdapter(
        fm: FragmentManager
) : FragmentStatePagerAdapter(fm) {
    private val list = mutableListOf<AdapterFragmentPager<*>>()

    inline fun <reified T : Fragment> append(title: CharSequence?,
                                             noinline creator: () -> T) {
        append(T::class.java, title, creator)
    }

    /**
     * 追加一個Fragment
     * @param clazz   Fragment類型的Class
     * @param title   标題
     * @param creator 建立該Fragment執行個體
     */
    fun <T : Fragment> append(clazz: Class<T>,
                              title: CharSequence?,
                              creator: () -> T) {
        list.add(AdapterFragmentPager(clazz, title, creator))
        notifyDataSetChanged()
    }

    inline fun <reified T : Fragment> indexOfType(): Int {
        return indexOfType(T::class.java)
    }

    /**
     * 擷取指定類型Fragment的下标
     */
    fun <T : Fragment> indexOfType(clazz: Class<T>): Int {
        return list.indexOfFirst { it.clazz == clazz }
    }

    inline fun <reified T : Fragment> removeByType() {
        removeByType(T::class.java)
    }

    /**
     * 移除指定類型的Fragment
     */
    fun <T : Fragment> removeByType(clazz: Class<T>) {
        list.removeAll { it.clazz == clazz }
        notifyDataSetChanged()
    }

    override fun getItem(position: Int): Fragment {
        return list[position].creator()
    }

    override fun getCount(): Int {
        return list.size
    }

    override fun getPageTitle(position: Int): CharSequence? {
        return list[position].title
    }

    override fun getItemPosition(pageFragment: Any): Int {
        return list.indexOfFirst {
            it.clazz.isInstance(pageFragment)
        }
    }

    private class AdapterFragmentPager<T : Fragment>(
            val clazz: Class<T>,
            val title: CharSequence?,
            val creator: () -> T
    )
}

           

下面是在activity中的使用方法

FragmentInstancePagerAdapter adapter = new FragmentInstancePagerAdapter(getSupportFragmentManager());
        adapter.append(ListSpeechFragment.class, "",
                () -> ListSpeechFragment.newInstance(detailInfo));
        adapter.append(BaseTikTokFragment.class, "",
                () -> new MainTikTokFragment());
mViewPager.setAdapter(adapter);
           

建立fragment，并且可以傳參的工廠方法

public static ListSpeechFragment newInstance(LiveDetailInfo detailInfo) {
        ListSpeechFragment f = new ListSpeechFragment();
        Bundle bundle = new Bundle();
        bundle.putParcelable(KEY_LIVE_DETAIL, detailInfo);
        f.setArguments(bundle);
        return f;
}
           

到此結束，簡單好用。