我正在开发 android 应用程序，我正在使用 Recycler Adapter 和 Sqlite 数据库来删除和更新 sqlite 数据库。
我的问题是，当我在 Recycler View 中单击要删除的项目时，它会从列表中删除数据，但是当我单击返回并再次打开列表时，已删除的数据仍然存在。
我已经从设备文件资源管理器检查了我的数据库，数据没有从数据库中删除。
同样的事情发生在更新上
这是我的回收器适配器类
public class UserRecyclerAdapterSavedUsers extends RecyclerView.Adapter<UserRecyclerAdapterSavedUsers.UserViewHolder> {
private List<User> listUsers;
Context mContext;
RecyclerView mRecyclerView;
ItemClickListenerLongPressed itemClickListenerLongPressed;
UserRecyclerAdapterSavedUsers userRecyclerAdapterSavedUsers;
View itemView;
public UserRecyclerAdapterSavedUsers(List<User> listUsers,RecyclerView recyclerView) {
this.listUsers = listUsers;
mRecyclerView=recyclerView;
}
@Override
public UserViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
mContext= parent.getContext();
itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_user_recycler_second, parent, false);
return new UserViewHolder(itemView);
}
/**
* ViewHolder class
*/
public class UserViewHolder extends RecyclerView.ViewHolder {
//public AppCompatTextView ID;
public AppCompatTextView textViewID;
public AppCompatTextView textViewName;
public AppCompatTextView textViewPassword;
public AppCompatTextView textViewRole;
LinearLayout layout;
public UserViewHolder(View view) {
super(view);
textViewID = (AppCompatTextView) view.findViewById(R.id.textViewID);
textViewName = (AppCompatTextView) view.findViewById(R.id.textViewName);
textViewPassword = (AppCompatTextView) view.findViewById(R.id.textViewPassword);
textViewRole = (AppCompatTextView) view.findViewById(R.id.textViewRole);
layout = (LinearLayout) view.findViewById(R.id.list_view);
}
}
@Override
public void onBindViewHolder(UserViewHolder holder, final int position) {
holder.textViewID.setText(listUsers.get(position).getUserid());
holder.textViewName.setText(listUsers.get(position).getName());
holder.textViewPassword.setText(listUsers.get(position).getPassword());
holder.textViewRole.setText(listUsers.get(position).getRole());
holder.layout.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
displayingAlertDialog(position);
return false;
}
});
}
public void setItemClickListenerLongPressed(ItemClickListenerLongPressed itemClickListenerLongPressed) {
this.itemClickListenerLongPressed = itemClickListenerLongPressed;
}
@Override
public int getItemCount() {
Log.v(UsersRecyclerAdapter.class.getSimpleName(),""+listUsers.size());
return listUsers.size();
}
private void displayingAlertDialog(final int position) {
final User user= new User();
//displaying alert dialog box
AlertDialog.Builder builder = new AlertDialog.Builder(itemView.getContext());
builder.setTitle("Choose Option");
builder.setMessage("Update or Delete?");
builder.setPositiveButton("Update", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//go to update activity
gotupdateuserActivity(user.getUserid());
// dialog.cancel();
}
});
builder.setNeutralButton("Delete", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//go to Remove Item
DatabaseHelper dbHelper = new DatabaseHelper(mContext);
dbHelper.deletePersonRecord(user.getUserid(), mContext);
listUsers.remove( position);
notifyItemRemoved(position);
mRecyclerView.removeViewAt(position);
notifyItemRangeChanged(position, listUsers.size());
notifyDataSetChanged();
dialog.cancel();
}
});
builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
AlertDialog alert11 = builder.create();
alert11.show();
}
public void remove(int position) {
listUsers.remove(position);
notifyItemRemoved(position);
}
private void gotupdateuserActivity(String userid) {
Intent goToUpdate = new Intent(mContext, UpdateUserRec.class);
goToUpdate.putExtra("USER_ID", userid);
Toast.makeText(mContext, "USER REC", Toast.LENGTH_SHORT).show();
mContext.startActivity(goToUpdate);
}
这是 Sqlite 数据库助手类
public class DatabaseHelper extends SQLiteOpenHelper {
// Database Version
private static final int DATABASE_VERSION = 2;
Context context;
// Database Name
private static final String DATABASE_NAME = "DynamicERP.db";
public static final String table_imei = "IMEITABLE";
public static final String table_login= "USERLOGIN";
// User Table Columns names
public static final String imeiid = "IMEIID";
public static final String imei = "IMEI";
public static final String userid = "USERID";
public static final String username = "USERNAME";
public static final String password = "PASSWORD";
public static final String userrole = "USERROLE";
// create table sql query
private static final String DATABASE_CIMEI = "CREATE TABLE " + table_imei + "("
+ imeiid + " INTEGER, " + imei + " VARCHAR );" ;
private static final String DATABASE_CUSER = "CREATE TABLE " + table_login + "("
+ userid + " INTEGER, " + username + " VARCHAR, " + password + " INTEGER, " + userrole + " VARCHAR );" ;
// drop table sql query
private String DROP_IMEI_TABLE = "DROP TABLE IF EXISTS " + table_imei;
private String DROP_USER_TABLE = "DROP TABLE IF EXISTS " + table_login;
/**
* Constructor
*
* @param context
*/
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DATABASE_CIMEI);
db.execSQL(DATABASE_CUSER);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//Drop User Table if exist
db.execSQL(DROP_USER_TABLE);
// Create tables again
onCreate(db);
}
/**
* This method is to create user record
*
* @param user
*/
public void addUser(User user) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(userid,user.getUserid());
values.put(username, user.getName());
values.put(password, user.getPassword());
values.put(userrole, user.getRole());
// Inserting Row
db.insert(table_login, null, values);
db.close();
}
public void addIMEI(User user) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(imei,user.getImei());
values.put(imeiid, user.getImeiid());
// Inserting Row
db.insert(table_imei, null, values);
db.close();
}
/**
* This method is to fetch all user and return the list of user records
*
* @return list
*/
public List<User> getAllUser() {
// array of columns to fetch
String[] columns = {
userid,
username,
password,
userrole
};
// sorting orders
String sortOrder =
userid + " ASC";
List<User> userList = new ArrayList<User>();
SQLiteDatabase db = this.getReadableDatabase();
// query the user table
/**
* Here query function is used to fetch records from user table this function works like we use sql query.
* SQL query equivalent to this query function is
* SELECT user_id,user_name,user_email,user_password FROM user ORDER BY user_name;
*/
Cursor cursor = db.query(table_login, //Table to query
columns, //columns to return
null, //columns for the WHERE clause
null, //The values for the WHERE clause
null, //group the rows
null, //filter by row groups
sortOrder); //The sort order
// Traversing through all rows and adding to list
if (cursor.moveToFirst()) {
do {
User user = new User();
//user.setId(Integer.parseInt(cursor.getString(cursor.getColumnIndex(userid))));
user.setUserid(cursor.getString(cursor.getColumnIndex(userid)));
user.setName(cursor.getString(cursor.getColumnIndex(username)));
user.setPassword(cursor.getString(cursor.getColumnIndex(password)));
user.setRole(cursor.getString(cursor.getColumnIndex(userrole)));
// Adding user record to list
userList.add(user);
} while (cursor.moveToNext());
}
cursor.close();
db.close();
// return user list
return userList;
}
/**
* This method is to fetch all user and return the list of user records
*
* @return list
*/
public List<User> getAllImei() {
// array of columns to fetch
String[] columns = {
imeiid,
imei,
};
// sorting orders
String sortOrder =
imeiid + " ASC";
List<User> userList = new ArrayList<User>();
SQLiteDatabase db = this.getReadableDatabase();
// query the user table
/**
* Here query function is used to fetch records from user table this function works like we use sql query.
* SQL query equivalent to this query function is
* SELECT user_id,user_name,user_email,user_password FROM user ORDER BY user_name;
*/
Cursor cursor = db.query(table_imei, //Table to query
columns, //columns to return
null, //columns for the WHERE clause
null, //The values for the WHERE clause
null, //group the rows
null, //filter by row groups
sortOrder); //The sort order
// Traversing through all rows and adding to list
if (cursor.moveToFirst()) {
do {
User user = new User();
//user.setId(Integer.parseInt(cursor.getString(cursor.getColumnIndex(userid))));
user.setImei(cursor.getString(cursor.getColumnIndex(imei)));
user.setImeiid(cursor.getString(cursor.getColumnIndex(imeiid)));
// Adding user record to list
userList.add(user);
} while (cursor.moveToNext());
}
cursor.close();
db.close();
// return user list
return userList;
}
/**
* This method to update user record
*
* @param receivedUSERId
* @param updateUserRec
* @param user
*/
public void updateUser(String receivedUSERId, UpdateUserRec updateUserRec, User user) {
SQLiteDatabase db = this.getWritableDatabase();
String strSQL = "UPDATE "+table_login+ " SET "+username+" = "+user.getName()+"," +
" "+password+" = "+user.getPassword()+","+userrole+" = "+user.getRole()+"" +
" WHERE "+userid+" = "+receivedUSERId;
db.execSQL(strSQL);
db.close();
}
/**
* This method is to delete user record
*
* @param user
*/
public void deleteUser(User user) {
SQLiteDatabase db = this.getWritableDatabase();
// delete user record by id
db.delete(table_login, userid + " = ?",
new String[]{String.valueOf(user.getUserid())});
db.close();
}
/**
* This method to check user exist or not
*
@param userid
* @return true/false
*/
public boolean checkUser(String userid) {
// array of columns to fetch
String[] columns = {
userid
};
SQLiteDatabase db = this.getReadableDatabase();
// selection criteria
String selection = userid + " = ?";
// selection argument
String[] selectionArgs = {userid};
// query user table with condition
/**
* Here query function is used to fetch records from user table this function works like we use sql query.
* SQL query equivalent to this query function is
* SELECT user_id FROM user WHERE imei = 'dynamic@imei.com';
*/
Cursor cursor = db.query(table_login, //Table to query
columns, //columns to return
selection, //columns for the WHERE clause
selectionArgs, //The values for the WHERE clause
null, //group the rows
null, //filter by row groups
null); //The sort order
int cursorCount = cursor.getCount();
cursor.close();
db.close();
if (cursorCount > 0) {
return true;
}
return false;
}
/**
* This method to check user exist or not
*
* @param email
* @param password
* @return true/false
*/
public boolean checkUser(String email, String password) {
// array of columns to fetch
String[] columns = {
userid
};
SQLiteDatabase db = this.getReadableDatabase();
// selection criteria
String selection = userid + " = ?" + " AND " + password + " = ?";
// selection arguments
String[] selectionArgs = {email, password};
// query user table with conditions
/**
* Here query function is used to fetch records from user table this function works like we use sql query.
* SQL query equivalent to this query function is
* SELECT user_id FROM user WHERE user_email = 'jack@androidtutorialshub.com' AND user_password = 'qwerty';
*/
Cursor cursor = db.query(table_login, //Table to query
columns, //columns to return
selection, //columns for the WHERE clause
selectionArgs, //The values for the WHERE clause
null, //group the rows
null, //filter by row groups
null); //The sort order
int cursorCount = cursor.getCount();
cursor.close();
db.close();
if (cursorCount > 0) {
return true;
}
return false;
}
/**
* This method to check user exist or not
*
* @param userid
* @param username
* @return true/false
*/
public boolean checkUserData(String userid, String username) {
// array of columns to fetch
String[] columns = {
userid
};
SQLiteDatabase db = this.getReadableDatabase();
// selection criteria
String selection = userid + " = ?" + " AND " + username + " = ?";
// selection arguments
String[] selectionArgs = {userid, username};
// query user table with conditions
/**
* Here query function is used to fetch records from user table this function works like we use sql query.
* SQL query equivalent to this query function is
* SELECT user_id FROM user WHERE user_email = 'jack@androidtutorialshub.com' AND user_password = 'qwerty';
*/
Cursor cursor = db.query(table_login, //Table to query
columns, //columns to return
selection, //columns for the WHERE clause
selectionArgs, //The values for the WHERE clause
null, //group the rows
null, //filter by row groups
null); //The sort order
int cursorCount = cursor.getCount();
cursor.close();
db.close();
if (cursorCount > 0) {
return true;
}
return false;
}
public boolean checkUserData(String userid) {
// array of columns to fetch
String[] columns = {
userid
};
SQLiteDatabase db = this.getReadableDatabase();
// selection criteria
String selection = userid + " = ?";
// selection argument
String[] selectionArgs = {userid};
// query user table with condition
/**
* Here query function is used to fetch records from user table this function works like we use sql query.
* SQL query equivalent to this query function is
* SELECT user_id FROM user WHERE user_email = 'dynamic@data.com';
*/
Cursor cursor = db.query(table_login, //Table to query
columns, //columns to return
selection, //columns for the WHERE clause
selectionArgs, //The values for the WHERE clause
null, //group the rows
null, //filter by row groups
null); //The sort order
int cursorCount = cursor.getCount();
cursor.close();
db.close();
if (cursorCount > 0) {
return true;
}
return false;
}
public User getUser(String id){
SQLiteDatabase db = this.getWritableDatabase();
String query= "SELECT * FROM "+table_login;
Cursor cursor = db.rawQuery(query, null);
User user = new User();
if(cursor.getCount() > 0) {
cursor.moveToFirst();
user.setUserid(cursor.getString(cursor.getColumnIndex(userid)));
user.setName(cursor.getString(cursor.getColumnIndex(username)));
user.setPassword(cursor.getString(cursor.getColumnIndex(password)));
user.setRole(cursor.getString(cursor.getColumnIndex(userrole)));
}
return user;
}
public void deletePersonRecord(String useridValue, Context mContext) {
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("DELETE FROM "+table_login+" WHERE "+userid +"='"+useridValue+"'");
Toast.makeText(mContext, "Deleted successfully.", Toast.LENGTH_SHORT).show();
db.close();
}
public void deleteIMEIRecord(String imeiidValue, Context mContext) {
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("DELETE FROM "+table_imei+" WHERE "+imeiid +"='"+imeiidValue+"'");
Toast.makeText(mContext, "Deleted successfully.", Toast.LENGTH_SHORT).show();
}
public void updateIMEI(String receivedIMEIId, UpdateIMEIRec updateIMEIRec, User user) {
SQLiteDatabase db = this.getWritableDatabase();
String strSQL = "UPDATE "+table_imei+ " SET "+imei+" = "+user.getImei()+"," +
" "+imeiid+" = "+user.getImeiid()+
" WHERE "+imeiid+" = "+receivedIMEIId;
db.execSQL(strSQL);
db.close();
}
public User getIMEI(String receivedIMEIId) {
SQLiteDatabase db = this.getWritableDatabase();
String query = "SELECT * FROM " + table_imei ;
Cursor cursor = db.rawQuery(query, null);
User user = new User();
if(cursor.getCount() > 0) {
cursor.moveToFirst();
user.setImeiid(cursor.getString(cursor.getColumnIndex(imeiid)));
user.setImei(cursor.getString(cursor.getColumnIndex(imei)));
}
return user;
}
这是我的 Recycler List Activity 类
public class UserUpdateListActivity extends AppCompatActivity {
AppCompatActivity activity = UserUpdateListActivity.this;
AppCompatTextView textViewName;
RecyclerView recyclerViewUsers;
AppCompatButton textViewButtonNewUser;
List<User> listUsers;
UserRecyclerAdapterSavedUsers userRecyclerAdapterSavedUsers;
DatabaseHelper databaseHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user_record_updated_list);
//getSupportActionBar().setTitle("");
initViews();
initObjects();
}
@Override
public void onBackPressed() {
super.onBackPressed();
startActivity(new Intent(UserUpdateListActivity.this,AdminMain.class));
finish();
}
@Override
protected void onRestart() {
super.onRestart();
}
/**
* This method is to initialize views
*/
private void initViews() {
textViewName = (AppCompatTextView) findViewById(R.id.textViewName);
textViewButtonNewUser = (AppCompatButton) findViewById(R.id.btnaddnew);
recyclerViewUsers = (RecyclerView) findViewById(R.id.recyclerViewUsers);
textViewButtonNewUser.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(UserUpdateListActivity.this,UserRecordSaveActivity.class));
}
});
}
/**
* This method is to initialize objects to be used
*/
private void initObjects() {
listUsers = new ArrayList<>();
userRecyclerAdapterSavedUsers = new UserRecyclerAdapterSavedUsers(listUsers,recyclerViewUsers);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getApplicationContext());
recyclerViewUsers.setLayoutManager(mLayoutManager);
recyclerViewUsers.setItemAnimator(new DefaultItemAnimator());
recyclerViewUsers.setHasFixedSize(true);
recyclerViewUsers.setAdapter(userRecyclerAdapterSavedUsers);
databaseHelper = new DatabaseHelper(activity);
String emailFromIntent = getIntent().getStringExtra("USERS");
textViewName.setText(emailFromIntent);
getDataFromSQLite();
}
/**
* This method is to fetch all user records from SQLite
*/
private void getDataFromSQLite() {
// AsyncTask is used that SQLite operation not blocks the UI Thread.
new AsyncTask<Void, Void, Void>() {
@Override
protected Void doInBackground(Void... params) {
listUsers.clear();
listUsers.addAll(databaseHelper.getAllUser());
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
userRecyclerAdapterSavedUsers.notifyDataSetChanged();
}
}.execute();
}
这是我用来删除数据的查询
public void deletePersonRecord(String useridValue, Context mContext) {
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("DELETE FROM "+table_login+" WHERE "+userid +"='"+useridValue+"'");
Toast.makeText(mContext, "Deleted successfully.", Toast.LENGTH_SHORT).show();
db.close();
}
这是我的回收商列表的图片
当我点击一个项目时，它会打开一个像这样的对话框 Dialog
当我点击删除时，会显示这个 Clicking on Delete
在那之后当我按下并再次打开我删除的数据时再次打开 Logcat 没有错误
这是我的更新 Activity
public class UpdateUserRec extends AppCompatActivity {
EditText UserIDUpdate,UserNameUpdate,UserPasswordUpdate,UserRoleUpdate;
Button BtnUserRecUpdate;
DatabaseHelper dbHelper;
String receivedUSERId;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_update_record);
UserIDUpdate= (EditText) findViewById(R.id.useridupdate);
UserNameUpdate= (EditText) findViewById(R.id.usernameupdate);
UserPasswordUpdate= (EditText) findViewById(R.id.userpasswordupdate);
UserRoleUpdate= (EditText) findViewById(R.id.userroleupdate);
BtnUserRecUpdate= (Button) findViewById(R.id.userbtnupdate);
dbHelper = new DatabaseHelper(this);
try {
//get intent to get person id
receivedUSERId= getIntent().getStringExtra("USER_ID");
} catch (Exception e) {
e.printStackTrace();
}
User user= dbHelper.getUser(receivedUSERId);
UserIDUpdate.setText(user.getUserid());
UserNameUpdate.setText(user.getName());
UserPasswordUpdate.setText(user.getPassword());
UserRoleUpdate.setText(user.getRole());
BtnUserRecUpdate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
updateUserFunction();
}
});
}
private void updateUserFunction() {
String useridupdate = UserIDUpdate.getText().toString().trim();
String usernameupdate = UserNameUpdate.getText().toString().trim();
String userpasswordupdate = UserRoleUpdate.getText().toString().trim();
String userroleupdate = UserRoleUpdate.getText().toString().trim();
if(useridupdate.isEmpty()){
//error name is empty
Toast.makeText(this, "Enter User ID", Toast.LENGTH_LONG).show();
}
if(usernameupdate.isEmpty()){
//error name is empty
Toast.makeText(this, "Enter User Name", Toast.LENGTH_LONG).show();
}
if(userpasswordupdate.isEmpty()){
//error name is empty
Toast.makeText(this, "Enter the password", Toast.LENGTH_LONG).show();
}
if(userroleupdate.isEmpty()){
//error name is empty
Toast.makeText(this, "Enter User Role", Toast.LENGTH_LONG).show();
}
//create updated person
User user = new User();
//call dbhelper update
dbHelper.updateUser(receivedUSERId, this, user);
//finally redirect back home
// NOTE you can implement an sqlite callback then redirect on success delete
goBackHome();
}
private void goBackHome() {
startActivity(new Intent(UpdateUserRec.this,UsersListActivity.class));
}
最佳答案
您正在从 RecyclerView 中显示数据的列表中删除数据。您应该记住数据库是您列表中的不同实体。数据库是数据的持久性存储，您从中删除项目的列表是非持久性存储。下次当您从数据库中获取数据时，列表将再次填充您之前删除的项目。
正确的方法是
- 从数据库中删除行
- 从适配器列表中删除项目
- notifyItemRemoved(位置)
你在SQL类中有这个方法
public List<User> getAllUser() { ... }
再创建一个方法
public boolean deleteUser(id){
db.delete(DATABASE_TABLE, KEY_NAME + "=" + id, null)
}
在删除项目时，使用特定的 Id 从您的适配器调用此方法，然后执行与之前相同的操作。
关于android - 从 Recycler 列表中删除但不从 Sqlite 数据库中删除的数据，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/54740698/