Question

我有一个ListView使用TaskView填充了TaskAdapter个对象（扩展了ArrayAdapter<Task>。每个TaskView都附带了TextView 3}}和两个AsyncTask用于状态更新。

我还有onProgressUpdate()的子类，其职责是监视正在进行的任务的进度。每当收到进度通知时，它都会将其传递给onProgressUpdate()方法。 TaskEvent方法应该根据它收到的TaskView更新列表中的视图。

我无法获得与使用列表Task添加的TaskAdapter对象相对应的public class ProgressMonitor extends AsyncTask<Void, TaskEvent, Void> { private Task task; private TaskView view; private ListView list; public ProgressMonitor(Task task, ListView list) { this.task = task; // I know leaving unchecked casts are a bad practice, but this was a temporary fix ArrayAdapter<Task> adapter = (ArrayAdapter<Task>) list.getAdapter(); adapter.add(task); this.view = // get view from adapter that corresponds to task } @Override protected Void doInBackground(Void... params) { // do stuff in background, send progress using publishProgress(TaskEvent) return null; } @Override protected void onProgressUpdate(TaskEvent... values) { TaskEvent e = values[0]; switch (e.getAction()) { case SOME_STATUS: // update view, but view is null break; case DIFFERENT_STATUS: // update view in a different way, but view is still null break; // etc. default: Log.w(TAG, "No action for " + e.getAction()); } } }。

以下是相关课程：

Task task = // ...
new ProgressMonitor(task, list).execute();

该类的使用方式如下：

{{1}}

Answer 1

每当您更改显示的数据时，您可能需要添加adapter.notifyDatasetChanged()。

Answer 2

for getting views of list you have to assign ListView list to your local object that is list
like this and set adapter to listview object then u will be abe to refresh the list in progress update
 public ProgressMonitor(Task task, ListView list) {
this.list = list; 
//you have to set apater to list view
list.setAdapter(Adptr);
}

@Override
    protected void onProgressUpdate(TaskEvent... values) {
        TaskEvent e = values[0];

        switch (e.getAction()) {
            case SOME_STATUS:
                // update view, but view is null

                adapter.notifyDataSetChanged();
                break;
            case DIFFERENT_STATUS:
                // update view in a different way, but view is still null
                break;
            // etc.
            default:
                Log.w(TAG, "No action for " + e.getAction());
        }
    }

从AsyncTask更新ListView的子项

2 个答案: