问题末尾的注意是更新但仍然不起作用
嘿大家我有一个列表和一个弹出窗口，我可以点击删除。
如何删除我在列表中长按的项目
此列表存储在本地 sqllite 数据库中。
我想单击删除以删除爱丁堡项目
我的清单代码：
public class ViewListContents extends AppCompatActivity {
DatabaseHelper myDB;
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.popup_layout, menu);
return true;
}
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewcontents_layout);
ListView listView = findViewById(R.id.listView);
myDB = new DatabaseHelper(this);
final MenuItem deleteItem, editItem;
final ArrayList<String> theList = new ArrayList<>();
final Cursor data = myDB.getListContents();
final ListAdapter listAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, theList);
listView.setAdapter(listAdapter);
deleteItem = findViewById(R.id.delete_item);
editItem = findViewById(R.id.edit_item);
final ListView finalListView = listView;
listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View v, final int position, final long id) {
PopupMenu p = new PopupMenu(ViewListContents.this, v);
MenuInflater inflater = p.getMenuInflater();
inflater.inflate(R.menu.popup_layout, p.getMenu());
p.show();
//Listener wait for the click on the popup menu item
p.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
@Override
public boolean onMenuItemClick(MenuItem item) {
Toast.makeText(getApplicationContext(),
item.getTitle(), Toast.LENGTH_SHORT).show();
switch (item.getItemId()) {
case R.id.delete_item:
finalListView.getItemAtPosition(position);
myDB.deleteEntry(finalListView.getSelectedItemPosition());
((ArrayAdapter) listAdapter).remove(listAdapter.getItem(position));
((ArrayAdapter) listAdapter).notifyDataSetChanged();
int x = ReadID(position);
myDB.deleteEntry(x);
myDB.getAllItems(Contract.YourEntry.COL2);
return true;
case R.id.edit_item:
getTheme();
return true;
default:
return true; //return ViewListContents.super.onOptionsItemSelected(deleteItem);
}
}
});
/* @Override
public boolean onOptionsItemSelected() {
switch (item.getItemId()) {
case R.id.delete_item:
theList.remove(position);
return true;
case R.id.edit_item:
getTheme();
return true;
default:
return ViewListContents.super.onOptionsItemSelected(deleteItem);
}
}*/
/* deleteItem.setOnActionExpandListener("Ok", new AlertDialog.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
theList.remove(position);
finalListView.setAdapter(listAdapter);
}
});*/
return true;
}
});
if (data.getCount() == 0) {
Toast.makeText(ViewListContents.this, "Your list is empty :(", Toast.LENGTH_LONG).show();
} else {
while (data.moveToNext()) {
theList.add(data.getString(1));
listView.setAdapter(listAdapter);
}
}
}
public int ReadID(int position){
DatabaseHelper mDbHelper = new DatabaseHelper(this);
SQLiteDatabase db = mDbHelper.getReadableDatabase();
String[] projection = {Contract.YourEntry.COL2};
String sortOrder = Contract.YourEntry.COL2 + " ASC";
Cursor cursor = db.query(
Contract.YourEntry.TABLE_NAME, // The table to query
null, // The array of columns to return (null to get all)
null, // The columns for the WHERE clause
null, // The values for the WHERE clause
null, // null if you don't want to group the rows
null, // null if you don't want filter by row groups
sortOrder // the order
);
try {
int idColumnIndex = cursor.getColumnIndex(Contract.YourEntry.intWhereToGoListOID);
int currentID = 0;
int count = 0;
while ((cursor.moveToNext() == true) && (count != (position + 1))) {
currentID = cursor.getInt(idColumnIndex + 1);
count ++;
}
return currentID;
} finally {
cursor.close();
}
}
}
这是我的数据库代码：
public class DatabaseHelper extends SQLiteOpenHelper {
// DATABASE
public static final String DATABASE_NAME = "mylist.db";
// TABLES
public static final String TABLE_TWHERETOGOLIST = "TWhereToGoList";
public static final String TABLE_NAME_2 = "TCategories";
public static final String TABLE_TListDefiniton = "TListDefinition";
// COLUMNS FOR TABLE: TWhereToGoList
public static final String intWhereToGoListOID = "WhereToGoListOID";
public static final String COL2 = "COL2";
public static final String intCategoriesOID = "CategoriesOID ";
public static final DateFormat dtDateLastModified = DateFormat.getDateInstance();
Date c = Calendar.getInstance().getTime();
SimpleDateFormat df = new SimpleDateFormat("dd-MMM-yyyy", Locale.getDefault());
public String formattedDate = df.format(c);
public static final String strDescription = "Description";
public static final String strGoogleLink = "GoogleLink";
public static final Integer bVisited = 0;
public static final Integer bRecommend = 0;
public static final Integer intListDefinitionOID = 0;
// COLUMNS FOR TABLE: TCategories
public static final Integer getIntListDefinitionOID = 0;
//public static final String strTitle = "strTitle"; // Both can get called from the top
//public static final String strDescription = "strDescription"; // Both can get called from the top
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.deleteDatabase(new File(DATABASE_NAME));
String createTable = "CREATE TABLE " + TABLE_TWHERETOGOLIST + " (intWhereToGoListOID INTEGER PRIMARY KEY AUTOINCREMENT, "
+ " COL2 TEXT, " + " intCategoriesOID TEXT, " + " strDescription TEXT, "
+ " strGoogleLink TEXT, " + " bVisited INTEGER)";
db.execSQL(createTable);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL(String.format("DROP IF TABLE EXISTS ", TABLE_TWHERETOGOLIST));
onCreate(db);
}
public boolean addData(String string) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL2, string);
long result = db.insert(TABLE_TWHERETOGOLIST, null, contentValues);
//if date as inserted incorrectly it will return -1
if (result == -1) {
return false;
} else {
return true;
}
}
public Cursor getListContents() {
SQLiteDatabase db = this.getWritableDatabase();
Cursor data = db.rawQuery("SELECT * FROM " + TABLE_TWHERETOGOLIST, null);
return data;
}
/*public int delete(int position) {
SQLiteDatabase db = this.getWritableDatabase();
if (db == null) {
Logger.getLogger("The DB is empty");
}
db.delete(TABLE_TWHERETOGOLIST, COL2 + " = ?", new String[]{ (intWhereToGoListOID) }); //new String[]{Long.toString(positionOfId)} );
另一个更新：
问题可能是您在此处引用的最后一行看到的 -1。
如果我在单击删除按钮后在此处写其他内容并再次从主要活动返回列表，则文本将被数字替换，并且某些元素被删除，而其他元素则获得一个数字或一些我可以写入的文本-1。
在另一种情况下，如果我在这个循环中多走几次，数字就会得到总结，而且令人毛骨悚然。
public void deleteEntry(int position) { SQLiteDatabase sqLiteDatabase = getWritableDatabase(); sqLiteDatabase.execSQL("DELETE FROM " + Contract.YourEntry.TABLE_NAME + " WHERE " + Contract.YourEntry.COL2 + " = " + position + ";"); sqLiteDatabase.execSQL("UPDATE " + Contract.YourEntry.TABLE_NAME + " SET " + Contract.YourEntry.COL2 + " = " + Contract.YourEntry.COL2 + " -1 " + " WHERE " + Contract.YourEntry.COL2 + " > " + position + ";"); }
Logger.getLogger("Successfully deleted the item!!!");
//Logger.getLogger(String.valueOf(getListContents()));
db.close();
return 1;
}
public Cursor getAllItems() {
SQLiteDatabase db = getReadableDatabase();
return db.query(
TABLE_TWHERETOGOLIST,
null,
null,
null,
null,
null,
null
);
}
}
如果您有任何问题，请在下面的评论中问我。感谢您的回复 ：）
更新 1.0：
我现在有一个问题，我不知道如何获取我长按并在出现的弹出窗口上按下删除的 ListView 项目的 ID。
我必须将这个 ListView 项目的（ID 随便）放到我的数据库代码中才能删除这个项目。
请询问您是否有问题。
请详细描述 :) 我不知道我该怎么做