响应 Activity 中的 ViewPager2 片段事件

Question

我有一个主 activity，其中包含一个 ViewPager2 和一个 TabLayout 以容纳一些片段。每个片段都会有按钮，我想在主 activity 中触发这些动作。但是，我没有看到如何设置 buttons/event 处理程序，以便在其中一个片段内按下按钮时通知主 activity 。谢谢！

MenuActivity.kt - ViewPager2/TabLayout 设置

private fun configureMenu() {
        // Create adapter
        val fragmentAdapter = PageAdapter(supportFragmentManager, lifecycle)
        // Add fragments
        fragmentAdapter.addFragment(CameraFragment(), getString(R.string.camera_tab))
        fragmentAdapter.addFragment(DevicesFragment(), getString(R.string.devices_tab))
        fragmentAdapter.addFragment(ConnectionFragment(), getString(R.string.connection_tab))
        // Set up pageviewer
        viewpager_menu.adapter = fragmentAdapter
        TabLayoutMediator(tablayout_main, viewpager_menu) { tab, position ->
            tab.text = fragmentAdapter.getPageTitle(position)
            viewpager_menu.setCurrentItem(tab.position, true)
        }.attach()
}

PageAdapter.kt

class PageAdapter(fm: FragmentManager, lifecycle: Lifecycle): FragmentStateAdapter(fm, lifecycle) {

    private var fragmentList = ArrayList<Fragment>()
    private var fragmentTitleList = ArrayList<String>()

    fun addFragment(fragment: Fragment, title: String) {
        fragmentList.add(fragment)
        fragmentTitleList.add(title)
    }

    override fun onAttachedToRecyclerView(recyclerView: RecyclerView) {
        super.onAttachedToRecyclerView(recyclerView)
    }

    override fun getItemCount(): Int {
        return fragmentList.size
    }

    override fun createFragment(position: Int): Fragment {
        return fragmentList[position]
    }

    fun getPageTitle(position: Int): String {
        return fragmentTitleList[position]
    }
}

CameraFragment.kt


class CameraFragment : Fragment() {

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
        return inflater.inflate(R.layout.fragment_camera, container, false)
    }

}

谢谢！

Answer 1

片段的内部动作

val main = this.activity!! as MainActivity
main.callSomeFunc()

Answer 2

你可以在特定的frament构造函数中传递activity的this对象并使用from fragment来调用activity class方法

例如：

 class MenuActivity : AppCompatActivity(){
    fragmentAdapter.addFragment(CameraFragment(this), getString(R.string.camera_tab))

}

  class CameraFragment : Fragment {
        var mActivity: MenuActivity? = null
        constructor(mActivity: MenuActivity?) {
            this.mActivity = mActivity
        }

        override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
            return inflater.inflate(R.layout.fragment_camera, container, false)
            
            onlick{
                mActivity.callMethodOfMenuActivity()
            }
        }
    }

响应 Activity 中的 ViewPager2 片段事件

Responding to ViewPager2 Fragments Events in Activity

android

android-fragments

kotlin

android-tablayout

android-viewpager2