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我是一個業餘的android開發人員，我想從數據庫中獲取用戶輸入的項目，然後將其顯示在一個片段中的recyclerview列表（不是ListView）中。如何在一個片段內的recylerview列表中顯示SQLite數據庫數據？
到目前爲止，我已經創建了將數據保存到其中的SQLite數據庫，我只想知道我可以在recyclerview中顯示所有這些信息。下面顯示的Java代碼顯示了我想要做的，但是在ListView中而不是在回收器視圖中。
DatabaseHelper
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String TAG = "DatabaseHelper";
public static final String DATABASE_NAME = "budget10.db";
public static final String TABLE_NAME = "expense_table";
public static final String TABLE_NAME2 = "income_table";
public static final String COL_1 = "_id";
public static final String COL_2 = "_id";
public static final String EXPENSE_AMOUNT = "EXPENSE_AMOUNT";
public static final String EXPENSE_DATE = "DATE";
public static final String EXPENSE_NOTES = "NOTES";
public static final String INCOME_AMOUNT = "INCOME_AMOUNT";
public static final String INCOME_DATE = "DATE";
public static final String INCOME_NOTES = "NOTES";
public static final String INCOME_CATEGORY = "INCOME_CATEGORY";
public static final String EXPENSE_CATEGORY = "EXPENSE_CATEGORY";
public static final String EXPENSE_ACCOUNT = "EXPENSE_ACCOUNT";
public static final String INCOME_ACCOUNT = "INCOME_ACCOUNT";
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 3);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table " + TABLE_NAME + " (_id INTEGER PRIMARY KEY AUTOINCREMENT, EXPENSE_AMOUNT DOUBLE,DATE INTEGER,NOTES TEXT, EXPENSE_CATEGORY TEXT, EXPENSE_ACCOUNT TEXT)");
db.execSQL("create table " + TABLE_NAME2 + " (_id INTEGER PRIMARY KEY AUTOINCREMENT,INCOME_AMOUNT DOUBLE,DATE INTEGER,NOTES TEXT, INCOME_CATEGORY TEXT, INCOME_ACCOUNT TEXT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME2);
onCreate(db);
}
public boolean insertexpenseData(Double amount_expense, String date_expense, String notes_expense, String category_expense, String expense_account) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(EXPENSE_AMOUNT, amount_expense);
contentValues.put(EXPENSE_DATE, date_expense);
contentValues.put(EXPENSE_NOTES, notes_expense);
contentValues.put(EXPENSE_CATEGORY, category_expense);
contentValues.put(EXPENSE_ACCOUNT, expense_account);
long result = db.insert(TABLE_NAME, null, contentValues);
if (result == -1)
return false;
else
return true;
}
public boolean insertincomeData(Double amount_income, String date_income, String notes_income, String category_income, String income_account) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(INCOME_AMOUNT, amount_income);
contentValues.put(INCOME_DATE, date_income);
contentValues.put(INCOME_NOTES, notes_income);
contentValues.put(INCOME_CATEGORY, category_income);
contentValues.put(INCOME_ACCOUNT, income_account);
long result = db.insert(TABLE_NAME2, null, contentValues);
if (result == -1)
return false;
else
return true;
}
public Cursor getexpenseData() {
SQLiteDatabase db = this.getWritableDatabase();
Cursor res = db.rawQuery("select * from " + TABLE_NAME, null);
return res;
}
public Cursor getincomeData() {
SQLiteDatabase db = this.getWritableDatabase();
Cursor res = db.rawQuery("select * from " + TABLE_NAME2, null);
return res;
}
public boolean updateexpenseData(String id, String amount, String date, String notes, String catagory_income) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_1, id);
contentValues.put(EXPENSE_AMOUNT, amount);
contentValues.put(EXPENSE_DATE, date);
contentValues.put(EXPENSE_NOTES, notes);
contentValues.put(EXPENSE_CATEGORY, catagory_income);
db.update(TABLE_NAME, contentValues, "_id = ?", new String[]{id});
return true;
}
public boolean updateincomeData(String id, String amount, String date, String notes, String catagory_income) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_2, id);
contentValues.put(INCOME_AMOUNT, amount);
contentValues.put(INCOME_DATE, date);
contentValues.put(INCOME_NOTES, notes);
contentValues.put(INCOME_CATEGORY, catagory_income);
db.update(TABLE_NAME2, contentValues, "_id = ?", new String[]{id});
return true;
}
public Integer deleteexpenseData(String _id) {
SQLiteDatabase db = this.getWritableDatabase();
return db.delete(TABLE_NAME, "_id = ?", new String[]{_id});
}
public Integer deleteincomeData(String _id) {
SQLiteDatabase db = this.getWritableDatabase();
return db.delete(TABLE_NAME2, "_id = ?", new String[]{_id});
}
public double getNetBudget() {
SQLiteDatabase db = this.getWritableDatabase();
String selectQuery = "SELECT TOTAL(INCOME_AMOUNT) - (SELECT TOTAL(EXPENSE_AMOUNT) FROM expense_table) FROM income_table";
Cursor cursor = db.rawQuery(selectQuery, null);
double netBudget = 0.00; // if there is no row, this will mean 0 is returned. You could also set it to -1, or throw an Exception if no record is returned
if (cursor.moveToFirst()) {
netBudget = cursor.getDouble(0);
}
cursor.close();
return netBudget;
}
public double getTotalExpense() {
SQLiteDatabase db = this.getWritableDatabase();
String selectQuery = "SELECT TOTAL(EXPENSE_AMOUNT) FROM expense_table";
Cursor cursor = db.rawQuery(selectQuery, null);
double netExpense = 0.00; // if there is no row, this will mean 0 is returned. You could also set it to -1, or throw an Exception if no record is returned
if (cursor.moveToFirst()) {
netExpense = cursor.getDouble(0);
}
cursor.close();
return netExpense;
}
public double getTotalIncome() {
SQLiteDatabase db = this.getWritableDatabase();
String selectQuery = "SELECT TOTAL(INCOME_AMOUNT) FROM income_table";
Cursor cursor = db.rawQuery(selectQuery, null);
double netIncome = 0.00; // if there is no row, this will mean 0 is returned. You could also set it to -1, or throw an Exception if no record is returned
if (cursor.moveToFirst()) {
netIncome = cursor.getDouble(0);
}
cursor.close();
return netIncome;
}
public void deleteAllIncome() {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_NAME2, null, null);
db.execSQL("delete from " + TABLE_NAME2);
db.close();
}
public void deleteAllExpense() {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_NAME, null, null);
db.execSQL("delete from " + TABLE_NAME);
db.close();
}
}
片段的ListView，我想變成一個recyclerview
public class tab2income extends Fragment {
private static final String TAG = "tab2income";
DatabaseHelper mDatabaseHelper;
private ListView mListView;
View rootView;
Cursor incomedata;
SimpleCursorAdapter sca;
DecimalFormat formatter = new DecimalFormat("0.00");
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.tab2income, container, false);
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mListView = (ListView) rootView.findViewById(R.id.listViewincome);
mListView.setEmptyView(rootView.findViewById(R.id.empty));
mDatabaseHelper = new DatabaseHelper(getActivity());
populateListView();
}
private void populateListView() {
Log.d(TAG, "populateListView: Displaying data in the ListView.");
incomedata = mDatabaseHelper.getincomeData();
sca = new SimpleCursorAdapter(getActivity(), android.R.layout.simple_list_item_1, incomedata, new String[]{DatabaseHelper.INCOME_AMOUNT}, new int[]{android.R.id.text1}, 0);
mListView.setAdapter(sca);
mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
int csrpos = incomedata.getPosition();
incomedata.moveToPosition(i);
displayNoteDate(
incomedata.getString(incomedata.getColumnIndex(DatabaseHelper.INCOME_NOTES)),
incomedata.getString(incomedata.getColumnIndex(DatabaseHelper.INCOME_DATE)),
incomedata.getString(incomedata.getColumnIndex(DatabaseHelper.INCOME_CATEGORY)),
l,
incomedata.getString(incomedata.getColumnIndex(DatabaseHelper.INCOME_ACCOUNT)));
incomedata.moveToPosition(csrpos);
}
});
}
@Override
public void onDestroy() {
super.onDestroy();
incomedata.close();
}
public void displayNoteDate(String noteContent, String dateValue,String category, final long noteID,String account) {
MaterialDialog.Builder builder= new MaterialDialog.Builder(getActivity())
.title("Income Information")
.content("Date: "+ dateValue+
"\nCategory: "+category+
"\nAccount: "+account+
"\nNote: "+noteContent)
.positiveText("close")
.negativeText("delete")
.onPositive(new MaterialDialog.SingleButtonCallback() {
@Override
public void onClick(@NonNull MaterialDialog dialog, @NonNull DialogAction which) {
}
})
.onNegative(new MaterialDialog.SingleButtonCallback() {
@Override
public void onClick(@NonNull MaterialDialog dialog, @NonNull DialogAction which) {
mDatabaseHelper.deleteincomeData(Long.toString(noteID));
incomedata = mDatabaseHelper.getincomeData();
sca.swapCursor(incomedata);
}
});
builder.show();
}
}
編輯
這就是我與迄今所做代碼在Sauro的答案中v巴什和我有recyclerview在我的XML文件，並沒有任何反應的項目被點擊時：
片段
public class tab2income extends Fragment implements ItemClickListener {
private static final String TAG = "tab2income";
DatabaseHelper mDatabaseHelper;
private RecyclerView mListView;
View rootView;
Cursor incomedata;
SimpleCursorAdapter sca;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.tab2income, container, false);
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mListView = rootView.findViewById(R.id.ListViewincome);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getActivity());
mListView.setLayoutManager(layoutManager);
mDatabaseHelper = new DatabaseHelper(getActivity());
populateListView();
}
private void populateListView() {
Log.d(TAG, "populateListView: Displaying data in the ListView.");
ArrayList<String> arrayList = new ArrayList<>();
MyAdapter myAdapter = new MyAdapter(arrayList);
mListView.setAdapter(myAdapter);
incomedata = mDatabaseHelper.getincomeData();
if(incomedata.moveToFirst()){
do {
arrayList.add(incomedata.getString(incomedata.getColumnIndex(DatabaseHelper.INCOME_AMOUNT)));
} while (incomedata.moveToNext());
}
myAdapter.notifyDataSetChanged();
}
@Override
public void onDestroy() {
super.onDestroy();
incomedata.close();
}
@Override
public void onClick(View view, int i) {
int csrpos = incomedata.getPosition();
incomedata.moveToPosition(i);
displayNoteDate(
incomedata.getString(incomedata.getColumnIndex(DatabaseHelper.INCOME_NOTES)),
incomedata.getString(incomedata.getColumnIndex(DatabaseHelper.INCOME_DATE)),
incomedata.getString(incomedata.getColumnIndex(DatabaseHelper.INCOME_CATEGORY)),
incomedata.getString(incomedata.getColumnIndex(DatabaseHelper.INCOME_ACCOUNT)));
incomedata.moveToPosition(csrpos);
}
public void displayNoteDate(String noteContent, String dateValue,String category,String account) {
MaterialDialog.Builder builder= new MaterialDialog.Builder(getActivity())
.title("Income Information")
.content("Date: "+ dateValue+
"\nCategory: "+category+
"\nAccount: "+account+
"\nNote: "+noteContent)
.positiveText("close")
.negativeText("delete")
.onPositive(new MaterialDialog.SingleButtonCallback() {
@Override
public void onClick(@NonNull MaterialDialog dialog, @NonNull DialogAction which) {
}
})
.onNegative(new MaterialDialog.SingleButtonCallback() {
@Override
public void onClick(@NonNull MaterialDialog dialog, @NonNull DialogAction which) {
}
});
builder.show();
}
}
適配器
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private final ArrayList<String> dataSet;
private ItemClickListener clickListener;
public MyAdapter(ArrayList<String> myDataset) {
dataSet = myDataset;
}
@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//layout of the list item
View view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.mTextView.setText(dataSet.get(position));
}
@Override
public int getItemCount() {
return dataSet.size();
}
public void setClickListener(ItemClickListener itemClickListener) {
this.clickListener = itemClickListener;
}
class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
final TextView mTextView;
ViewHolder(View v) {
super(v);
//textview for showing results
mTextView = v.findViewById(android.R.id.text1);
v.setOnClickListener(this);
}
//for click
@Override
public void onClick(View view) {
if (clickListener != null) clickListener.onClick(view, getAdapterPosition());
}
}
}
我建議您使用新的Android架構組件。這是很容易的，並且需要更少的代碼。 https://developer.android.com/topic/libraries/architecture/index.html –