更新
感谢@EmanuelSeibold，我能够确定更新Recyclerview的问题。 AsyncTask在后台工作正常，只有recyclerview的适配器更新冻结了UI。
UPDATE2
我发现这确实是我的布局设置。我忘了删除RecyclerView周围的nestedScrollView。这似乎导致渲染冲突。
我在这里挖掘了答案和博客文章，但似乎无法找到解决方案。
我对Android开发很新，并试图了解多线程。
场景：我有一个应用程序，它包含一个带有课程数据的SQLite数据库，并实现了一个查询该数据库的搜索功能。这会阻止UI线程约3秒钟。 因此，我实现了AsyncTask以保持UI响应，但在搜索过程中我的UI仍然被阻止。
提前致谢！
这里是代码：
搜索活动
public class Activity_Search extends Activity_Base {
private RecyclerView rv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search);
setActionBarTitle(R.string.title_search);
findViewById(R.id.searchCourseTitle).setOnKeyListener(new View.OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
switch(keyCode) {
case KeyEvent.KEYCODE_ENTER:
startSearch();
break;
default:
return false;
}
return true;
}
});
rv = (RecyclerView) findViewById(R.id.searchRecycler);
Adapter_Search adapter = new Adapter_Search(this, null);
rv.setAdapter(adapter);
rv.setLayoutManager(new LinearLayoutManager(this));
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.search_FAB);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startSearch();
}
});
}
private void startSearch() {
findViewById(R.id.searchCourseTitle).clearFocus();
if (this.getCurrentFocus() != null) {
InputMethodManager imm =
(InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(this.getCurrentFocus().getWindowToken(), 0);
}
{getting input}
String[] columns = {...};
String selection = {formatting input};
Async_Search search = new Async_Search(this);
search.execute(columns, new String[]{selection});
}
public void onSearchCompleted(Cursor results) {
((Adapter_Search) rv.getAdapter()).changeCursor(results);
}
}
的AsyncTask
public class Async_Search extends AsyncTask<String[], Void, Cursor> {
private Activity activity;
public Async_Search (Activity activity) {
this.activity = activity;
}
@Override
protected Cursor doInBackground(String[]... params) {
SQLiteDatabase db = SQL_Database.getInstance(activity).getWritableDatabase();
String[] columns = params[0];
String selection = params[1][0];
return db.query(...)
}
@Override
protected void onPostExecute(Cursor results) {
((Activity_Search) activity).onSearchCompleted(results);
}
}
Recycler adapter
public class Adapter_Search extends RecyclerCursorAdapter<Adapter_Search.ViewHolder>{
public static class ViewHolder extends RecyclerView.ViewHolder {
public TextView name, ects, studipCode, termYear, lecturers, fields;
public ViewHolder (View view) {
super(view);
{id lookups}
}
}
public Adapter_Search(Context context, Cursor cursor) {
super(context, cursor);
}
@Override
public ViewHolder onCreateViewHolder (ViewGroup parent, int ViewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.search_list_entry, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
@Override
public void onBindViewHolder (ViewHolder viewHolder, Cursor cursor) {
TextView name, ects, studipCode, termYear, lecturers, fields;
name = viewHolder.name;
ects = viewHolder.ects;
studipCode = viewHolder.studipCode;
termYear = viewHolder.termYear;
lecturers = viewHolder.lecturers;
fields = viewHolder.fields;
String termandyear = cursor.getString(cursor.getColumnIndexOrThrow(SQL_Database.COURSE_COLUMN_TERM)) +
String.format("%.2s",cursor.getString(cursor.getColumnIndexOrThrow(SQL_Database.COURSE_COLUMN_YEAR)));
name.setText(cursor.getString(cursor.getColumnIndexOrThrow(SQL_Database.COURSE_COLUMN_COURSE)));
String credits = cursor.getString(cursor.getColumnIndexOrThrow(SQL_Database.COURSE_COLUMN_ECTS)) + " ECTS";
ects.setText(credits);
{and so on}
}
}
基础适配器类
public abstract class RecyclerCursorAdapter <ViewHolder extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<ViewHolder> {
private Context mContext;
private Cursor mCursor;
private boolean mDataValid;
private int mRowIdColumn;
private DataSetObserver mDataSetObserver;
public RecyclerCursorAdapter(Context context, Cursor cursor) {
mContext = context;
mCursor = cursor;
mDataValid = cursor != null;
mRowIdColumn = mDataValid ? mCursor.getColumnIndex("_id") : -1;
mDataSetObserver = new NotifyingDataSetObserver();
if (mCursor != null) {
mCursor.registerDataSetObserver(mDataSetObserver);
}
}
public Cursor getCursor() {
return mCursor;
}
@Override
public int getItemCount() {
if (mDataValid && mCursor != null) {
return mCursor.getCount();
}
return 0;
}
@Override
public long getItemId(int position) {
if (mDataValid && mCursor != null && mCursor.moveToPosition(position)) {
return mCursor.getLong(mRowIdColumn);
}
return 0;
}
@Override
public void setHasStableIds(boolean hasStableIds) {
super.setHasStableIds(true);
}
public abstract void onBindViewHolder(ViewHolder viewHolder, Cursor cursor);
@Override
public void onBindViewHolder(ViewHolder viewHolder, int position) {
if (!mDataValid) {
throw new IllegalStateException("this should only be called when the cursor is valid");
}
if (!mCursor.moveToPosition(position)) {
throw new IllegalStateException("couldn't move cursor to position " + position);
}
onBindViewHolder(viewHolder, mCursor);
}
/**
* Change the underlying cursor to a new cursor. If there is an existing cursor it will be
* closed.
*/
public void changeCursor(Cursor cursor) {
Cursor old = swapCursor(cursor);
if (old != null) {
old.close();
}
}
/**
* Swap in a new Cursor, returning the old Cursor. Unlike
* {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em>
* closed.
*/
public Cursor swapCursor(Cursor newCursor) {
if (newCursor == mCursor) {
return null;
}
final Cursor oldCursor = mCursor;
if (oldCursor != null && mDataSetObserver != null) {
oldCursor.unregisterDataSetObserver(mDataSetObserver);
}
mCursor = newCursor;
if (mCursor != null) {
if (mDataSetObserver != null) {
mCursor.registerDataSetObserver(mDataSetObserver);
}
mRowIdColumn = newCursor.getColumnIndexOrThrow("_id");
mDataValid = true;
notifyDataSetChanged();
} else {
mRowIdColumn = -1;
mDataValid = false;
notifyDataSetChanged();
//There is no notifyDataSetInvalidated() method in RecyclerView.Adapter
}
return oldCursor;
}
private class NotifyingDataSetObserver extends DataSetObserver {
@Override
public void onChanged() {
super.onChanged();
mDataValid = true;
notifyDataSetChanged();
}
@Override
public void onInvalidated() {
super.onInvalidated();
mDataValid = false;
notifyDataSetChanged();
//There is no notifyDataSetInvalidated() method in RecyclerView.Adapter
}
}
}
答案 0 :(得分：0)
也许尝试从异步搜索中删除这些行。
gpa而是这样打电话：
first_name, last_name = input("Please input your First Name and Last Name: ").split()
gpa = float(input("Please enter your GPA: "))
honor_message = ""
if gpa <=0:
print("GPA can not be negative or 0")
else:
if 3.75 <= gpa <= 4.0:
honor_message="\033[1;31;0m Excellent \x1b[0m"
elif 3.5 <= gpa <= 3.74:
honor_message = "\033[1;31;0m Good \x1b[0m"
elif 3.25 <= gpa <= 3.49:
honor_message = "\033[1;31;0m Satisfactory \x1b[0m"
else:
honor_message
print("Some text some text".center(60))
print("Some text some text Some text some text".center(60))
print("Some text some text".center(60))
print(first_name.center(60).rstrip(), last_name)
print("Some text some text".center(60))
print("Some text some text".center(60))
print(honor_message.center(60))
print("Some text some text".center(60))
我不知道这是否有效，但我的Asynctask并没有使用你的活动。