我试图在从设备库读取后在 recyclerview 中显示所有图像，但 recyclerview 未显示任何图像。
主要活动：
class MainActivity : AppCompatActivity() {
private lateinit var imageAdapter: ImageAdapter
private lateinit var binding: ActivityMainBinding
private val REQUEST = 112
@RequiresApi(Build.VERSION_CODES.TIRAMISU)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(R.layout.activity_main)
imageAdapter = ImageAdapter()
checkPermission()
val format = SimpleDateFormat("dd-MM-yyyy")
val strDate = format.format(Date())
binding.btnDate.text = strDate
val imgList = getImagesPath(this, strDate)
prepareRecyclerView()
setImageList(imgList)
}
private fun setImageList(imgList: ArrayList<String?>) {
imageAdapter.setImageList(imgList as ArrayList<String>)
}
fun funclick(view: View) {
pickDateTime()
}
private fun prepareRecyclerView() {
binding.recyclerView.apply {
layoutManager = GridLayoutManager(context, 2, GridLayoutManager.VERTICAL, false)
adapter = imageAdapter
}
}
private fun checkPermission() {
if (ContextCompat.checkSelfPermission(
this,
Manifest.permission.READ_EXTERNAL_STORAGE
)
!= PackageManager.PERMISSION_GRANTED
)
ActivityCompat.requestPermissions(
this,
arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE),
REQUEST
)
}
private fun pickDateTime() {
val currentDateTime = Calendar.getInstance()
val startYear = currentDateTime.get(Calendar.YEAR)
val startMonth = currentDateTime.get(Calendar.MONTH)
val startDay = currentDateTime.get(Calendar.DAY_OF_MONTH)
DatePickerDialog(
this,
DatePickerDialog.OnDateSetListener { picker, year, month, day ->
val calendar = Calendar.getInstance()
calendar.set(Calendar.YEAR, picker.year)
calendar.set(Calendar.MONTH, picker.month)
calendar.set(Calendar.DATE, picker.dayOfMonth)
val format = SimpleDateFormat("dd-MM-yyyy")
val strDate = format.format(calendar.getTime())
val imgList: ArrayList<String?> = getImagesPath(this, strDate)
setImageList(imgList)
},
startYear,
startMonth,
startDay
).show()
}
fun getImagesPath(activity: Activity, strDate: String): ArrayList<String?> {
val listOfAllImages = ArrayList<String?>()
val cursor: Cursor?
val column_index_folder_name: Int
var PathOfImage: String? = null
val uri: Uri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI
val projection = arrayOf<String>(
MediaStore.MediaColumns.DATA,
MediaStore.Images.Media.BUCKET_DISPLAY_NAME
)
cursor = activity.contentResolver.query(
uri, projection, null,
null, null
)
val column_index_data: Int = cursor!!.getColumnIndexOrThrow(MediaStore.MediaColumns.DATA)
column_index_folder_name = cursor
.getColumnIndexOrThrow(MediaStore.Images.Media.BUCKET_DISPLAY_NAME)
while (cursor.moveToNext()) {
PathOfImage = cursor.getString(column_index_data)
val file: File = File(PathOfImage)
if (file.exists()) {
val date = file.lastModified()
val yourDate = Date(date)
val formatter: DateFormat = SimpleDateFormat("dd-MM-yyyy")
val formattedDate: String = formatter.format(yourDate)
if (strDate.equals(formattedDate)) listOfAllImages.add(PathOfImage)
}
// listOfAllImages.add(PathOfImage)
}
return listOfAllImages
}
}
ImageAdapter:
class ImageAdapter : RecyclerView.Adapter<ImageAdapter.ImageViewHolder>() {
private var imgList: List<String> = ArrayList()
// var actionMenu: (String) -> Unit = {}
fun setImageList(imgCount: List<String>) {
this.imgList = imgCount
notifyDataSetChanged()
}
inner class ImageViewHolder(val binding: ImageCardBinding) :
RecyclerView.ViewHolder(binding.root) {
init {
binding.imgCategory.setOnClickListener {
// actionMenu.invoke(categoryList[position].strCategory)
}
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ImageViewHolder {
println("called1")
return ImageViewHolder(ImageCardBinding.inflate(LayoutInflater.from(parent.context)))
}
override fun onBindViewHolder(holder: ImageViewHolder, position: Int) {
println("called1")
holder.binding.apply {
text1.text = "sadasda"
// imgCategory.setImageBitmap(BitmapFactory.decodeFile(imgList[position]))
Glide.with(holder.itemView)
.load(R.drawable.ic_launcher_background)
.centerCrop()
.into(imgCategory)
}
}
override fun getItemCount(): Int {
return imgList.size
}
}
activity_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<com.google.android.material.button.MaterialButton
android:id="@+id/btn_date"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="50dp"
android:onClick="funclick"
android:text="@string/lbl_select_date"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
android:layout_marginStart="@dimen/value_6"
android:scrollbars="none"
app:layout_constraintTop_toBottomOf="@id/btn_date" />
</androidx.constraintlayout.widget.ConstraintLayout>
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="190dp"
android:layout_height="150dp"
android:layout_marginTop="10dp"
android:layout_marginEnd="@dimen/value_10"
android:layout_marginStart="@dimen/value_10">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center">
<androidx.cardview.widget.CardView
android:id="@+id/cardview"
android:layout_width="180dp"
android:layout_height="match_parent"
app:layout_constraintStart_toStartOf="parent"
android:elevation="10dp"
app:cardCornerRadius="8dp">
<ImageView
android:id="@+id/img_category"
android:layout_width="180dp"
android:layout_height="150dp"
android:scaleType="fitCenter"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/text1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="10dp"
android:text="asdsad"
android:layout_gravity="bottom"/>
</androidx.cardview.widget.CardView>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
MainActivity 正在将图像列表发送到 ImageAdapter。我看到图像发送到适配器，但不知何故 recyclerview 适配器没有显示。在 ImageAdapter 中，onBindViewHolder 中，getItemCount 没有被调用。
您面临的问题可能与
onCreateMainActivitybindingbindingonCreate@RequiresApi(Build.VERSION_CODES.TIRAMISU)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root) // Use binding.root to set the content view
imageAdapter = ImageAdapter()
checkPermission()
val format = SimpleDateFormat("dd-MM-yyyy")
val strDate = format.format(Date())
binding.btnDate.text = strDate
val imgList = getImagesPath(this, strDate)
prepareRecyclerView()
setImageList(imgList)
}
此更改可确保您的活动的内容视图正确设置为绑定对象的膨胀布局。
此外，请确保
ImageAdapterRecyclerViewactivity_main.xmlapp:layoutManager"androidx.recyclerview.widget.LinearLayoutManager"如果
onBindViewHoldergetItemCountRecyclerViewprepareRecyclerViewsetImageList如果您已经验证了这些要点但仍然遇到问题，请检查 logcat 中是否有任何错误消息，这些消息可能会提供有关问题所在的更多信息。