[英]Saving CheckBox state with SQLite Database
我正在構建一個使用SQLite數據庫保存列表項的列表應用程序。 列表項由UUID,名稱和布爾值組成,以確定是否解決了該問題(數據庫將其存儲為int)。 我注意到的是,當用戶關閉某個任務並添加了新任務時,該列表會重新加載,以便現在取消選中已選中的任務。 此外,重新啟動應用程序后,列表會重新加載,因此所有已選中的任務都將變為未選中狀態。
現在,我一直在思考想法,到目前為止,我所做的是在onBindViewHolder()方法的TaskAdapter類中,我調用setOnCheckedChangedListener()以便在用戶檢查任務時啟動烤面包。 我覺得我應該在這里做一些事情來更新數據庫中的特定任務,但是我不知道如何做。
附加說明:我使用的是singleton類,其中包含所有數據庫方法,例如添加任務,更新任務以及從數據庫中檢索所有任務。
ListFragment.java
public class ListFragment extends Fragment implements AddTaskDialog.addTask{
private static final String ADD_TASK_TAG = "ADD_TASK_DIALOG";
private RecyclerView mRecyclerView;
private TaskAdapter mAdapter;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_list, container, false);
mRecyclerView = view.findViewById(R.id.recycler_view);
LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
mRecyclerView.setLayoutManager(layoutManager);
updateUI();
return view;
}
private void updateUI(){
List<Task> tasks = TaskLab.getTaskLab(getContext()).getTaskList();
if(mAdapter == null) {
mAdapter = new TaskAdapter(tasks);
mRecyclerView.setAdapter(mAdapter);
}else{
mAdapter.setTaskList(tasks);
mAdapter.notifyDataSetChanged();
}
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
super.onCreateOptionsMenu(menu, inflater);
inflater.inflate(R.menu.toolbar_layout,menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()){
case R.id.add_task_button:
// Launch a dialog.
AddTaskDialog dialog = new AddTaskDialog();
FragmentManager manager = getFragmentManager();
dialog.setTargetFragment(ListFragment.this,1);
dialog.show(manager,ADD_TASK_TAG);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
// Part of the addTask interface created in AddTaskDialog
@Override
public void addTask(String taskName) {
Task task = new Task();
task.setName(taskName);
TaskLab.getTaskLab(getContext()).addTask(task);
updateUI();
}
}
TaskAdapter.java
public class TaskAdapter extends RecyclerView.Adapter<TaskAdapter.TaskHolder> {
private List<Task> mTaskList;
public TaskAdapter(List<Task> tasks){
mTaskList = tasks;
}
@Override
public TaskAdapter.TaskHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_layout,parent,false);
return new TaskHolder(view);
}
@Override
public void onBindViewHolder(TaskAdapter.TaskHolder holder, int position) {
Task task = mTaskList.get(position);
holder.bindData(task);
holder.mTaskCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {
if(isChecked){
Toast.makeText(compoundButton.getContext(),"Task Solved!",Toast.LENGTH_SHORT).show();
}
}
});
}
@Override
public int getItemCount() {
return mTaskList.size();
}
public void setTaskList(List<Task> tasks) {
mTaskList = tasks;
}
public class TaskHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private TextView mTaskName;
private CheckBox mTaskCheckBox;
public TaskHolder(View itemView) {
super(itemView);
mTaskName = itemView.findViewById(R.id.task_name);
mTaskCheckBox = itemView.findViewById(R.id.task_checkbox);
}
private void bindData(Task task) {
mTaskName.setText(task.getName());
mTaskCheckBox.setChecked(task.isSolved());
}
@Override
public void onClick(View view) {
}
}
}
TaskLab.java (Singleton類)
public class TaskLab {
private static TaskLab sTaskLab;
private Context mContext;
private SQLiteDatabase mDatabase;
private TaskLab(Context context) {
mContext = context.getApplicationContext();
mDatabase = new TaskBaseHelper(mContext).getWritableDatabase();
}
public static TaskLab getTaskLab(Context context){
if(sTaskLab == null) {
sTaskLab = new TaskLab(context);
}
return sTaskLab;
}
// Add DataBase operation method here.
private ContentValues getContentValues(Task task) {
ContentValues values = new ContentValues();
values.put(TaskTable.Cols.UUID, task.getId().toString());
values.put(TaskTable.Cols.NAME, task.getName());
values.put(TaskTable.Cols.SOLVED, task.isSolved() ? 1 : 0);
return values;
}
public void addTask(Task task) {
ContentValues values = getContentValues(task);
mDatabase.insert(TaskTable.TABLE_NAME,null,values);
}
// Don't really understand this method
public void updateTask(Task task) {
String uuidString = task.getId().toString();
ContentValues values = getContentValues(task);
mDatabase.update(TaskTable.TABLE_NAME,values, TaskTable.Cols.UUID + " = ?",
new String[] {uuidString});
}
public TaskCursorWrapper queryTasks(String whereClause, String[] whereArgs) {
Cursor cursor = mDatabase.query(TaskTable.TABLE_NAME,null,whereClause,whereArgs,null,null,null);
return new TaskCursorWrapper(cursor);
}
public List<Task> getTaskList(){
List<Task> taskList = new ArrayList<>();
TaskCursorWrapper cursor = queryTasks(null,null);
try{
cursor.moveToFirst();
while(!cursor.isAfterLast()){
Task task = cursor.getTask();
taskList.add(task);
cursor.moveToNext();
}
}finally {
cursor.close();
}
return taskList;
}
在適配器中,當您使用onclick時,當前項將更新,但是在滾動單擊的位置時復選框將不匹配。 因為適配器僅考慮您從ur代碼編寫的位置。 因此,請使用任何吸氣劑/阻焊劑來避免此問題。
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