我想用Notes编写简单的管理器。 我有一个SQLite数据库，其中包含一些数据，如下所示：
_id | time | date | text
1 | 9:45 | 12.01| blabla
2 | 21:01| 13.01| albalb
...| ... | ... | ...
我还有一个班级Note：
public class Note {
private int id;
private String time;
private String date;
private String text;
public Note(final int id, final String time, final String date, final String text){
setId(id);
setTime(time);
setDate(date);
setText(text);
}
public int getId(){
return id;
}
public String getTime(){
return time;
}
public String getDate(){
return date;
}
public String getText(){
return text;
}
void setId(final int id){
this.id = id;
}
void setTime(final String time){
this.time = time;
}
void setDate(final String date){
this.date = date;
}
void setText(final String text){
this.text = text;
}
}
和NotesManager：
public class NotesManager {
private static final String TABLE_NAME = "NotesListTable";
private static final String KEY_TIME = "time";
private static final String KEY_DATE = "date";
private static final String KEY_TEXT = "text";
private static final String KEY_ID = "_id";
private final SQLiteDatabase db;
public NotesManager(SQLiteDatabase db){
this.db = db;
}
public void save(final ContentValues cv){
db.insert(TABLE_NAME, null, cv);
}
public void delete(final int id){
db.delete(TABLE_NAME, KEY_ID + "=" + id, null);
}
public Note getNoteById(final int id){
Cursor mCursor = db.query(TABLE_NAME, null, KEY_ID + "=" + id, null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return new Note(mCursor.getInt(mCursor.getColumnIndex(KEY_ID)),
mCursor.getString(mCursor.getColumnIndex(KEY_TIME)),
mCursor.getString(mCursor.getColumnIndex(KEY_DATE)),
mCursor.getString(mCursor.getColumnIndex(KEY_TEXT)));
}
public Cursor getAllDataFromDB(){
return db.query(TABLE_NAME, null, null, null, null, null, null);
}
public String[] getKeysArray(){
return new String[] {KEY_ID, KEY_TIME, KEY_DATE, KEY_TEXT};
}
}
我有一个ListView片段： 它是由Android Studio生成的，我做了一些修改，添加了SimpleCursorAdapter
public class NotesListFragment extends Fragment implements AbsListView.OnItemClickListener {
private static final String ARG_SECTION_NUMBER = "section_number";
private int mSectionNumber = 0;
private OnFragmentInteractionListener mListener;
private AbsListView mListView;
private SimpleCursorAdapter scAdapter;
private Cursor cursor;
ImageButton deleteButton;
NotesManager notesManager = new NotesManager(OrganizerApp.db);
public static NoesListFragment newInstance(int param1) {
NoesListFragment fragment = new NotesListFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, param1);
fragment.setArguments(args);
return fragment;
}
public NotesListFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mSectionNumber = getArguments().getInt(ARG_SECTION_NUMBER);
}
cursor = NotesManager.getAllDataFromDB();
//TODO: startManagingCursor(cursor)
//mAdapter = new ArrayAdapter<NotesListContent.NotesItem>(getActivity(),
// android.R.layout.simple_list_item_1, android.R.id.text1, NotesListContent.ITEMS);
scAdapter = new SimpleCursorAdapter(getActivity(),
R.layout.note_list_rowlayout,
cursor,
notesManager.getKeysArray(),
new int[]{R.id.note_list_rowlayout_item1,
R.id.note_list_rowlayout_item2,
R.id.note_list_rowlayout_item3,
R.id.note_list_rowlayout_item4 });
deleteButton = (ImageButton) getView().
findViewById(R.id.note_list_rowlayout_deleteButton);
deleteButton.setOnClickListener(onClickDeleteButton);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_note, container, false);
// Set the adapter
mListView = (AbsListView) view.findViewById(android.R.id.list);
mListView.setAdapter(scAdapter);
//((AdapterView<ListAdapter>) mListView).setAdapter(mAdapter);
// Set OnItemClickListener so we can be notified on item clicks
mListView.setOnItemClickListener(this);
return view;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mSectionNumber = getArguments().getInt(ARG_SECTION_NUMBER);
mListener = (OnFragmentInteractionListener) activity;
((MainActivity) activity).onSectionAttached(mSectionNumber);
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if (null != mListener) {
// Notify the active callbacks interface (the activity, if the
// fragment is attached to one) that an item has been selected.
// mListener.onFragmentInteraction(NotesListContent.ITEMS.get(position).id);
}
}
public void setEmptyText(CharSequence emptyText) { // If list is empty.
View emptyView = mListView.getEmptyView();
if (emptyView instanceof TextView) {
((TextView) emptyView).setText(emptyText);
}
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFragmentInteraction(String id);
}
View.OnClickListener onClickDeleteButton = new View.OnClickListener() {
@Override
public void onClick(View v) {
}
};
}
Android studio也生成了NotesListContent.java：
public class NotesListContent {
public static List<Note> ITEMS = new ArrayList<Note>();
//public static Map<String, Note> ITEM_MAP = new HashMap<String, Note>();
private static void addItem(Note item) {
ITEMS.add(item);
//ITEM_MAP.put(item.id, item);
}
/**
* A dummy item representing a piece of content.
public static class NoteItem {
public String id;
public String content;
public NoteItem(String id, String content) {
this.id = id;
this.content = content;
}
@Override
public String toString() {
return content;
}
}*/
}
所以我的解决方案有效，但我认为这很糟糕。
特别是这段代码似乎非常不方便：
scAdapter = new SimpleCursorAdapter（getActivity（）， R.layout.note_list_rowlayout， 光标， notesManager.getKeysArray（） new int [] {R.id.note_list_rowlayout_item1， R.id.note_list_rowlayout_item2， R.id.note_list_rowlayout_item3， R.id.note_list_rowlayout_item4}）;
答案 0 :(得分：1)
我已经完成了自己的笔记管理员，所以我会尝试回答你的问题。
我需要一个NotesListContent.java？我该如何使用它？
这有点MVC模式，数据与视图分离。尝试将其视为一个实体，或者更好地将其视为单个注释条目描述。
如何在不弃用simpleCursorAdapter的情况下使用ListView？
a）从simpleCursorAdapter何时贬值？只有其中一个构造函数是。
b）你可以使用第二个构造函数，或者扩展一些适配器类（例如ArrayAdapter）你自己
如何在不刷新所有ListView的情况下删除和添加项目？
您向dataAdapter添加数据，然后将dataAdapter设置为ListView的适配器（listview.setAdapter（adapter））。
如果您没有调用adapter.notifyDataSetChanged（），则listview的视图将不会更新。
特别是这段代码似乎非常不方便（...）
它有什么不妥之处？但如果是这样，请随意使用......：
String[] columns = new String[] { // The desired columns to be bound
"timestamp",
"title",
"content",
};
// the XML defined views which the data will be bound to
int[] map_to = new int[] {
R.id.timestamp,
R.id.title,
R.id.content,
};
dataAdapter = new SimpleCursorAdapter(
this, R.layout.some_xml_here,
db.getAllItems(),
columns,
map_to,
0);