在我的Android记事应用中，如果长按某个记事，然后选择“删除”以删除该记事，该记事仍存在于列表中，那么在我关闭该应用然后返回至该记事后，记事消失了！
提示：我正在使用onContextItemSelected方法显示“删除”选项。
如何从列表和数据库中删除注释？
MainActivity类包含onContextItemSelected方法：
package com.twitter.i_droidi.mynotes;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.util.List;
public class MainActivity extends ActionBarActivity implements AdapterView.OnItemClickListener {
ListView lv;
NotesDataSource nDS;
List<NotesModel> notesList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nDS = new NotesDataSource(this);
lv = (ListView) findViewById(R.id.lv);
nDS.open();
notesList = nDS.getAllNotes();
nDS.close();
String[] notes = new String[notesList.size()];
for (int i = 0; i < notesList.size(); i++) {
notes[i] = notesList.get(i).getTitle();
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1,
android.R.id.text1, notes);
lv.setAdapter(adapter);
registerForContextMenu(lv);
lv.setOnItemClickListener(this);
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent nView = new Intent(this, Second2.class);
nView.putExtra("id", notesList.get(position).getId());
nView.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(nView);
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_delete, menu);
super.onCreateContextMenu(menu, v, menuInfo);
}
@Override
public boolean onContextItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.delete:
nDS.open();
nDS.deleteNote("id"); // Check...!!!
nDS.close();
Toast nDelete = Toast.makeText(this, R.string.deleted, Toast.LENGTH_LONG);
nDelete.show();
}
return super.onContextItemSelected(item);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.mainMenuNewNote:
Intent nNote = new Intent(this, Second.class);
startActivity(nNote);
return true;
case R.id.mainMenuAbout:
AlertDialog.Builder aboutDialog = new AlertDialog.Builder(this);
aboutDialog.setTitle(getString(R.string.about_title));
aboutDialog.setMessage(R.string.about_body);
aboutDialog.setIcon(R.drawable.my_notes);
aboutDialog.setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface aboutDialog, int witch) {
// Do Not Do Anything.
}
});
aboutDialog.show();
return true;
case R.id.mainMenuExit:
AlertDialog.Builder exDialog = new AlertDialog.Builder(this);
exDialog.setTitle(R.string.exit_title);
exDialog.setMessage(R.string.exit_body);
exDialog.setIcon(R.drawable.my_notes);
exDialog.setNegativeButton(R.string.yes, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface exDialog, int which) {
finish();
}
});
exDialog.setPositiveButton(R.string.no, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface exDialog, int which) {
// Do Not Do Anything.
}
});
exDialog.show();
return true;
}
return super.onOptionsItemSelected(item);
}
}
DB类：
package com.twitter.i_droidi.mynotes;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DB extends SQLiteOpenHelper {
private static final String DB_NAME = "MyNotes";
private static final int DB_VERSION = 1;
public static final String TABLE_NAME = "MyNotes";
public static final String ID = "id";
public static final String TITLE = "title";
public static final String BODY = "body";
private static final String DB_CREATE = "create table " + TABLE_NAME + " (" + ID + " integer primary key autoincrement, " +
TITLE + " text not null, " + BODY + " text not null)";
public DB(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DB_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
}
NotesDataSource类：
package com.twitter.i_droidi.mynotes;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
import java.util.ArrayList;
import java.util.List;
public class NotesDataSource {
DB myDB;
SQLiteDatabase sql;
String[] getAllColumns = new String[]{DB.ID, DB.TITLE, DB.BODY};
public NotesDataSource(Context context) {
myDB = new DB(context);
}
public void open() {
try {
sql = myDB.getWritableDatabase();
} catch (Exception ex) {
Log.d("Error in your database!", ex.getMessage());
}
}
public void close() {
sql.close();
}
public void createNote(String title, String body) {
ContentValues note = new ContentValues();
note.put(myDB.TITLE, title);
note.put(myDB.BODY, body);
sql.insert(myDB.TABLE_NAME, null, note);
}
public NotesModel getNote(int id) {
NotesModel note = new NotesModel();
Cursor cursor = sql.rawQuery("SELECT * FROM " + DB.TABLE_NAME + " WHERE " + DB.ID + " = ?", new String[]{id + ""});
if (cursor.getCount() > 0) {
cursor.moveToFirst();
note.setId(cursor.getInt(0));
note.setTitle(cursor.getString(1));
note.setBody(cursor.getString(2));
cursor.close();
}
return note;
}
public void updateNote(int id, String title, String body) {
ContentValues note = new ContentValues();
note.put(myDB.TITLE, title);
note.put(myDB.BODY, body);
sql.update(myDB.TABLE_NAME, note, myDB.ID + " = " + id, null);
}
public void deleteNote(Object id) {
sql.delete(myDB.TABLE_NAME, myDB.ID + " = " + id, null);
}
public List<NotesModel> getAllNotes() {
List<NotesModel> notesList = new ArrayList<NotesModel>();
StringBuffer selectQuery = new StringBuffer();
selectQuery.append("SELECT * FROM "+ myDB.TABLE_NAME +"");
Cursor cursor = sql.rawQuery(selectQuery.toString(), null);
if(cursor != null && cursor.moveToFirst()) {
do {
NotesModel notes = new NotesModel();
notes.setId(cursor.getInt(0));
notes.setTitle(cursor.getString(1));
notes.setBody(cursor.getString(2));
notesList.add(notes);
} while (cursor.moveToNext());
}
cursor.close();
return notesList;
}
}
最佳答案
从数据库中删除项目后
从中删除已删除的项目
String[] notes
通过使用
notes.remove(position);
通话
adapter.notifyDataSetChanged();
关于java - 无法从Android记事本应用程序的列表和数据库中删除记事本，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/31047665/