解决 Android ViewPager2 意外跳转：精确控制页面导航

class ViewActivity : BaseActivity() {

   private lateinit var binding: ActivityView
   private lateinit var adapter: ViewAdapter // 假设这是 ViewPager2 的适配器

   override fun onCreate(savedInstanceState: Bundle?){
      super.onCreate(savedInstanceState)
      // ... 初始化 binding ...

      adapterViewPager()
      goToNextPage() // 问题所在：在 onCreate 中无条件调用
      goToBackPage() // 问题所在：在 onCreate 中无条件调用
   }

   private fun goToNextPage(){
      binding.viewPager.setCurrentItem(binding.viewPager.currentItem + 1)
   }

   private fun goToBackPage(){
      binding.viewPager.setCurrentItem(binding.viewPager.currentItem - 1)
   }
}

class TakePictureFragment : Fragment() {

   private lateinit var binding : FragmentTakePicture

   override fun onViewCreated(view: View, savedInstanceState: Bundle?){
      super.onViewCreated(view, savedInstanceState)

      next() // 封装了一个按钮监听器
   }

   private fun next(){
      binding.buttonNext.setOnClickListener {
         // 假设 parent.goToNextPage() 是 ViewActivity 中的导航方法
         (activity as? ViewActivity)?.goToNextPage()
      }
   }
}

class ViewActivity : BaseActivity() {

   private lateinit var binding: ActivityViewBinding // 假设使用 ViewBinding
   private lateinit var adapter: ViewAdapter

   override fun onCreate(savedInstanceState: Bundle?){
      super.onCreate(savedInstanceState)
      binding = ActivityViewBinding.inflate(layoutInflater) // 初始化 ViewBinding
      setContentView(binding.root)

      setupViewPager() // 仅初始化 ViewPager 适配器
      // 移除 goToNextPage() 和 goToBackPage() 在 onCreate 中的直接调用
      // 导航操作应通过其他方式（如按钮点击）触发
   }

   private fun setupViewPager(){
      adapter = ViewAdapter(supportFragmentManager, lifecycle)

      adapter.addFragment(HelloWordFragment())
      adapter.addFragment(TakePictureFragment())
      adapter.addFragment(LoginFragment())
      adapter.addFragment(ConfirmEmailFragment())

      binding.viewPager.adapter = adapter
   }

   // 这些方法应由用户交互触发，例如按钮点击
   fun goToNextPage(){
      binding.viewPager.setCurrentItem(binding.viewPager.currentItem + 1, true) // 增加平滑滚动
   }

   fun goToBackPage(){
      binding.viewPager.setCurrentItem(binding.viewPager.currentItem - 1, true) // 增加平滑滚动
   }
}

class TakePictureFragment : Fragment() {

   private var _binding: FragmentTakePictureBinding? = null // 使用可空属性，防止内存泄漏
   private val binding get() = _binding!! // 非空断言，确保在 onViewCreated 之后访问

   override fun onCreateView(
      inflater: LayoutInflater, container: ViewGroup?,
      savedInstanceState: Bundle?
   ): View {
      _binding = FragmentTakePictureBinding.inflate(inflater, container, false)
      return binding.root
   }

   override fun onViewCreated(view: View, savedInstanceState: Bundle?){
      super.onViewCreated(view, savedInstanceState)

      // 直接设置按钮监听器，通过 Activity 接口调用导航
      binding.buttonNext.setOnClickListener {
         (activity as? ViewActivity)?.goToNextPage()
      }
      // ... 其他逻辑，如触发相机或权限请求 ...
   }

   override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
      super.onActivityResult(requestCode, resultCode, data)
      if (resultCode == Activity.RESULT_OK) { // 使用 Activity.RESULT_OK
            when (requestCode) {
                REQUEST_IMAGE_CAPTURE -> {
                    // 处理拍照结果，更新 UI，但不在此处触发页面跳转
                    // 例如：显示拍摄的照片
                }
                REQUEST_GALLERY_IMAGE -> {
                    // 处理相册选择结果
                }
            }
      }
      // 在 onActivityResult 中处理完结果后，不应自动跳转。
      // 如果需要跳转，应等待用户点击“下一步”按钮。
   }

   override fun onDestroyView() {
      super.onDestroyView()
      _binding = null // 清除 binding 引用，避免内存泄漏
   }

   companion object {
       const val REQUEST_IMAGE_CAPTURE = 1
       const val REQUEST_GALLERY_IMAGE = 2
   }
}