我在ViewHolder中分配了视图，但是当尝试访问 OnBindViewHolder 中的 Button 或尝试在 OnCreateViewHolder OnClickListerner 时>，应用程序崩溃并说“试图在空对象引用上调用虚拟方法” ...但是另一方面，当尝试在TextView上设置setText时，它会起作用
适配器类
public class DownloadManagerAdapter extends RecyclerView.Adapter<DownloadManagerAdapter.ViewHolder> {
static String TAG = "rrDebug";
private void AskForDelete(final ViewHolder viewHolder) {
new AlertDialog.Builder(MyApplication.getInstance().getContext())
//set message, title, and icon
.setTitle("Delete video")
.setMessage("Are you sure want to proceed ?")
.setIcon(R.drawable.ic_delete)
.setPositiveButton("Delete", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
new File(DownloadManagerActivity.DownloadManager.getImpl().get(viewHolder.position).getPath()).delete();
viewHolder.updateNotDownloaded(FileDownloadStatus.INVALID_STATUS, 0, 0);
dialog.dismiss();
}
})
.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
})
.create();
}
private FileDownloadListener downloadItemListener = new FileDownloadSampleListener() {
private ViewHolder checkCurrentHolder(final BaseDownloadTask task) {
final ViewHolder tag = (ViewHolder) task.getTag();
if (tag.id != task.getId()) {
return null;
}
return tag;
}
@Override
protected void pending(BaseDownloadTask task, int soFarBytes, int totalBytes) {
super.pending(task, soFarBytes, totalBytes);
final ViewHolder tag = checkCurrentHolder(task);
if (tag == null) {
return;
}
tag.updateDownloading(FileDownloadStatus.pending, soFarBytes
, totalBytes);
tag.downloadItemStatus.setText(R.string.dlmng_status_pending);
}
@Override
protected void started(BaseDownloadTask task) {
super.started(task);
final ViewHolder tag = checkCurrentHolder(task);
if (tag == null) {
return;
}
tag.downloadItemStatus.setText(R.string.dlmng_status_started);
}
@Override
protected void connected(BaseDownloadTask task, String etag, boolean isContinue, int soFarBytes, int totalBytes) {
super.connected(task, etag, isContinue, soFarBytes, totalBytes);
final ViewHolder tag = checkCurrentHolder(task);
if (tag == null) {
return;
}
tag.updateDownloading(FileDownloadStatus.connected, soFarBytes
, totalBytes);
tag.downloadItemStatus.setText(R.string.dlmng_status_connected);
}
@Override
protected void progress(BaseDownloadTask task, int soFarBytes, int totalBytes) {
super.progress(task, soFarBytes, totalBytes);
final ViewHolder tag = checkCurrentHolder(task);
if (tag == null) {
return;
}
tag.updateDownloading(FileDownloadStatus.progress, soFarBytes
, totalBytes);
}
@Override
protected void error(BaseDownloadTask task, Throwable e) {
super.error(task, e);
final ViewHolder tag = checkCurrentHolder(task);
if (tag == null) {
return;
}
tag.updateNotDownloaded(FileDownloadStatus.error, task.getLargeFileSoFarBytes()
, task.getLargeFileTotalBytes());
DownloadManagerActivity.DownloadManager.getImpl().removeTaskForViewHolder(task.getId());
}
@Override
protected void paused(BaseDownloadTask task, int soFarBytes, int totalBytes) {
super.paused(task, soFarBytes, totalBytes);
final ViewHolder tag = checkCurrentHolder(task);
if (tag == null) {
return;
}
tag.updateNotDownloaded(FileDownloadStatus.paused, soFarBytes, totalBytes);
tag.downloadItemStatus.setText(R.string.dlmng_status_paused);
DownloadManagerActivity.DownloadManager.getImpl().removeTaskForViewHolder(task.getId());
}
@Override
protected void completed(BaseDownloadTask task) {
super.completed(task);
final ViewHolder tag = checkCurrentHolder(task);
if (tag == null) {
return;
}
tag.updateDownloaded();
DownloadManagerActivity.DownloadManager.getImpl().removeTaskForViewHolder(task.getId());
}
};
private View.OnClickListener fancyButtonClickListeners = new View.OnClickListener() {
@Override
public void onClick(View v) {
if (v.getTag() == null) {
return;
}
ViewHolder holder = (ViewHolder) v.getTag();
switch (v.getId()){
case R.id.dlmng_item_download:
// to start
final DownloadManagerActivity.DownloadManagerModel model = DownloadManagerActivity.DownloadManager.getImpl().get(holder.position);
final BaseDownloadTask task = FileDownloader.getImpl().create(model.getUrl())
.setPath(model.getPath())
.setCallbackProgressTimes(100)
.setListener(downloadItemListener);
DownloadManagerActivity.DownloadManager.getImpl()
.addTaskForViewHolder(task);
DownloadManagerActivity.DownloadManager.getImpl()
.updateViewHolder(holder.id, holder);
task.start();
break;
case R.id.dlmng_item_pause:
// to pause
FileDownloader.getImpl().pause(holder.id);
break;
case R.id.dlmng_item_view:
Log.i(TAG, "No Player To Play File");
break;
case R.id.dlmng_item_delete:
// to delete
AskForDelete(holder);
//new File(DownloadManagerActivity.DownloadManager.getImpl().get(holder.position).getPath()).delete();
//holder.updateNotDownloaded(FileDownloadStatus.INVALID_STATUS, 0, 0);
break;
}
}
};
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.cell_download_manager, parent, false);
ViewHolder viewHolder = new ViewHolder(v);
// set onClickListener on FancyButtons
Log.d(TAG, "setOnClickListener on FancyButtons");
viewHolder.downloadItemDownloadBtn.setOnClickListener(fancyButtonClickListeners);
viewHolder.downloadItemPauseBtn.setOnClickListener(fancyButtonClickListeners);
viewHolder.downloadItemPlayBtn.setOnClickListener(fancyButtonClickListeners);
viewHolder.downloadItemDeleteBtn.setOnClickListener(fancyButtonClickListeners);
return viewHolder;
}
@Override
public void onBindViewHolder(final ViewHolder viewHolder, int position) {
final DownloadManagerActivity.DownloadManagerModel model = DownloadManagerActivity.DownloadManager.getImpl().get(position);
viewHolder.update(model.getId(), position);
viewHolder.downloadItemName.setText(model.getName());
DownloadManagerActivity.DownloadManager.getImpl()
.updateViewHolder(viewHolder.id, viewHolder);
if (DownloadManagerActivity.DownloadManager.getImpl().isReady()) {
final int status = DownloadManagerActivity.DownloadManager.getImpl().getStatus(model.getId(), model.getPath());
if (status == FileDownloadStatus.pending || status == FileDownloadStatus.started ||
status == FileDownloadStatus.connected) {
// start task, but file not created yet
viewHolder.updateDownloading(status, DownloadManagerActivity.DownloadManager.getImpl().getSoFar(model.getId())
, DownloadManagerActivity.DownloadManager.getImpl().getTotal(model.getId()));
} else if (!new File(model.getPath()).exists() &&
!new File(FileDownloadUtils.getTempPath(model.getPath())).exists()) {
// not exist file
viewHolder.updateNotDownloaded(status, 0, 0);
} else if (DownloadManagerActivity.DownloadManager.getImpl().isDownloaded(status)) {
// already downloaded and exist
viewHolder.updateDownloaded();
} else if (status == FileDownloadStatus.progress) {
// downloading
viewHolder.updateDownloading(status, DownloadManagerActivity.DownloadManager.getImpl().getSoFar(model.getId())
, DownloadManagerActivity.DownloadManager.getImpl().getTotal(model.getId()));
} else {
// not start
viewHolder.updateNotDownloaded(status, DownloadManagerActivity.DownloadManager.getImpl().getSoFar(model.getId())
, DownloadManagerActivity.DownloadManager.getImpl().getTotal(model.getId()));
}
} else {
viewHolder.downloadItemStatus.setText(R.string.dlmng_status_loading);
}
}
@Override
public int getItemCount() {
return DownloadManagerActivity.DownloadManager.getImpl().getTaskCounts();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
private TextView downloadItemName;
private TextView downloadItemStatus;
private TextView downloadItemSize;
private TextView downloadItemSpeed;
private ProgressBar downloadItemProgressBar;
private ImageButton downloadItemPlayBtn;
private ImageButton downloadItemDownloadBtn;
private ImageButton downloadItemPauseBtn;
private ImageButton downloadItemDeleteBtn;
public ViewHolder(View itemView) {
super(itemView);
downloadItemName = (TextView) itemView.findViewById(R.id.dlmng_download_Name);
downloadItemStatus = (TextView) itemView.findViewById(R.id.dlmng_download_status);
downloadItemSize = (TextView) itemView.findViewById(R.id.dlmng_download_size);
downloadItemSpeed = (TextView) itemView.findViewById(R.id.dlmng_download_speed);
downloadItemProgressBar = (ProgressBar) itemView.findViewById(R.id.dlmng_progress_bar);
downloadItemPlayBtn = (ImageButton) itemView.findViewById(R.id.dlmng_item_view);
downloadItemPlayBtn = (ImageButton) itemView.findViewById(R.id.dlmng_item_download);
downloadItemPauseBtn = (ImageButton) itemView.findViewById(R.id.dlmng_item_pause);
downloadItemDeleteBtn = (ImageButton) itemView.findViewById(R.id.dlmng_item_delete);
}
/**
* viewHolder position
*/
private int position;
/**
* download id
*/
private int id;
public void update(final int id, final int position) {
this.id = id;
this.position = position;
}
public void updateDownloaded() {
downloadItemProgressBar.setMax(1);
downloadItemProgressBar.setProgress(1);
downloadItemStatus.setText(R.string.dlmng_status_completed);
// Play Button Visible
Log.d(TAG, "play button visible as item downloaded");
downloadItemDownloadBtn.setVisibility(View.GONE);
downloadItemPauseBtn.setVisibility(View.GONE);
downloadItemPlayBtn.setVisibility(View.VISIBLE);
}
public void updateNotDownloaded(final int status, final long sofar, final long total) {
if (sofar > 0 && total > 0) {
final float percent = sofar
/ (float) total;
downloadItemProgressBar.setMax(100);
downloadItemProgressBar.setProgress((int) (percent * 100));
} else {
downloadItemProgressBar.setMax(1);
downloadItemProgressBar.setProgress(0);
}
switch (status) {
case FileDownloadStatus.error:
downloadItemStatus.setText(R.string.dlmng_status_error);
break;
case FileDownloadStatus.paused:
downloadItemStatus.setText(R.string.dlmng_status_paused);
break;
default:
downloadItemStatus.setText(R.string.dlmng_status_not_downloaded);
break;
}
// Play Button Visible
Log.d(TAG, "download button visible as item not downloaded");
downloadItemDownloadBtn.setVisibility(View.VISIBLE);;
downloadItemPauseBtn.setVisibility(View.GONE);
downloadItemPlayBtn.setVisibility(View.GONE);
}
public void updateDownloading(final int status, final long sofar, final long total) {
final float percent = sofar
/ (float) total;
downloadItemProgressBar.setMax(100);
downloadItemProgressBar.setProgress((int) (percent * 100));
switch (status) {
case FileDownloadStatus.pending:
downloadItemStatus.setText(R.string.dlmng_status_pending);
break;
case FileDownloadStatus.started:
downloadItemStatus.setText(R.string.dlmng_status_started);
break;
case FileDownloadStatus.connected:
downloadItemStatus.setText(R.string.dlmng_status_connected);
break;
case FileDownloadStatus.progress:
downloadItemStatus.setText(R.string.dlmng_status_progress);
break;
default:
downloadItemStatus.setText(MyApplication.getInstance().getContext().getString(
R.string.dlmng_status_downloading, status));
break;
}
// Pause Button Visible
Log.d(TAG, "pause button visible as item is currently downloading");
downloadItemDownloadBtn.setVisibility(View.GONE);
downloadItemPauseBtn.setVisibility(View.VISIBLE);
downloadItemPlayBtn.setVisibility(View.GONE);
}
} }
cell_download_manager.xml
<LinearLayout ... android:background="@drawable/cell_download_manager" ... > <LinearLayout ... > <TextView android:id="@+id/dlmng_download_Name" ... /> <TextView android:id="@+id/dlmng_download_status" ... /> <LinearLayout ... > <TextView android:id="@+id/dlmng_download_size" ... /> <TextView android:id="@+id/dlmng_download_speed" ... /> </LinearLayout> <ProgressBar android:id="@+id/dlmng_progress_bar" ... /> </LinearLayout> <ImageButton android:id="@+id/dlmng_item_download" ... /> <ImageButton android:id="@+id/dlmng_item_pause" ... /> <ImageButton android:id="@+id/dlmng_item_view" ... /> <ImageButton android:id="@+id/dlmng_item_delete" ... /> </LinearLayout>
更新pastebin中的第1部分目录 https://pastebin.com/D4wLVAMT
更新第2部分-> DownloadManagerActivity.class https://pastebin.com/i3bZDcB3
对不起，对于PASTEBIN，但问题长度有限制
答案 0 :(得分：0)
问题直截了当
您正在onCreateViewHolder内设置fancyButtonClickListeners
onClickMethod中没有单击的项目引用
您没有与单击的项目相对应的数据
请将clickListener操作移至onBindViewHolder。这将解决问题。最好使用新的OnClickListener（）{}代替fancyButtonClickListeners变量
答案 1 :(得分：0)
最后我得到了一个包含以下代码的解决方案.....分别分配了clickListener，然后在onBindViewHolder中使用它们
这就是我所做的
UserModule