我在DataBase中有一个表，我想创建一个表。 现在，根据表格中的信息，我会做很多CheckBox，只显示其中一些是没有意义的。我听说过listview 但是我如何listview checkbox我在互联网上找到listview的例子，当我尝试插入大量信息时，只有一半信息进来，所以我被告知做adapter。 你有一个如何做到这一点的例子吗？
它是DatabaseHandler：
package budgetreport.com.budgetreport;
public class DatabaseHandler extends SQLiteOpenHelper {
// All Static variables
// Database Version
private static final int DATABASE_VERSION = 4;
// Database Name
private static final String DATABASE_NAME = "Records_Item Purcashes";
// Contacts table name
private static final String TABLE_RECORDS = "Records";
// Contacts Table Columns names
private static final String KEY_ID = "ID";
private static final String KEY_PRICE = "Price";
private static final String KEY_ITEM = "Item";
private static final String KEY_DETAILS = "Details";
private static final String KEY_DATE = "Date";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_RECORDS + "("
+ KEY_ID + " INTEGER PRIMARY KEY,"
+ KEY_PRICE + " INTEGER," + KEY_ITEM + " TEXT,"
+ KEY_DETAILS + " TEXT, " + KEY_DATE + " TEXT" + ")";
db.execSQL(CREATE_CONTACTS_TABLE);
}
// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_RECORDS);
// Create tables again
onCreate(db);
}
// Adding new contact
public void addRecord(Record record) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_ID, record.getId()); // Contact Name
values.put(KEY_PRICE, record.getPrice()); // Contact Name
values.put(KEY_ITEM, record.getItem()); // Contact Name
values.put(KEY_DETAILS, record.getDetails()); // Contact Name
values.put(KEY_DATE, record.getDetails()); // Contact Phone Number
// Inserting Row
db.insert(TABLE_RECORDS, null, values);
db.close(); // Closing database connection
}
// Getting single contact
public Record getRecord(int id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_RECORDS, new String[] { KEY_ID, KEY_PRICE,
KEY_ITEM, KEY_DETAILS, KEY_DATE }, KEY_ID + "=?",
new String[] { String.valueOf(id) }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
Record record = new Record(Integer.parseInt(cursor.getString(0)),
Integer.parseInt(cursor.getString(1)), cursor.getString(2), cursor.getString(3), cursor.getString(4));
// return contact
return record;
}
// Getting All Contacts
public List<Record> getAllContacts() {
List<Record> contactList = new ArrayList<Record>();
// Select All Query
String selectQuery = "SELECT * FROM " + TABLE_RECORDS;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Record record = new Record();
record.setId(Integer.parseInt(cursor.getString(0)));
record.setPrice(Integer.parseInt(cursor.getString(1)));
record.setItem(cursor.getString(2));
record.setDetails(cursor.getString(3));
record.setDate(cursor.getString(4));
// Adding contact to list
contactList.add(record);
} while (cursor.moveToNext());
}
// return contact list
return contactList;
}
// Getting contacts Count
public int getRecordsCount() {
String countQuery = "SELECT * FROM " + TABLE_RECORDS;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
// cursor.close();
// return count
return cursor.getCount();
}
// Updating single contact
public int updateContact(Record record) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_ID, record.getId());
values.put(KEY_PRICE, record.getPrice());
values.put(KEY_DETAILS, record.getDetails());
values.put(KEY_DATE, record.getDate());
// updating row
return db.update(TABLE_RECORDS, values, KEY_ID + " = ?",
new String[] { String.valueOf(record.getPrice()) });
}
// Deleting single contact
public void deleteContact(Record record) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_RECORDS, KEY_ID + " = ?",new String[]
{String.valueOf(record.getPrice()) });
db.close();
}
}
答案 0 :(得分：2)
进展相对简单。
涉及到
- a）向数据库助手添加一个方法，根据id删除。
- b）（i）修改onClick监听器以调用delete方法（简单循环），然后（ii）更新listview（循环之后）。
但是，原始的自定义适配器有一些缺陷，原始光标是通过mCsr保留的，并且没有考虑更改Cursor（交换）时更改的复选框数。
因此，适配器已经删除了对mCsr的引用，并被传递的Cursor或通过调用getCursor方法替换。此外，swapCursor()方法已被覆盖，以调整mCheckBoxes的元素数量并重新初始化elemnets（设置为false）。
a）新的 deleteRecord 方法： -
public boolean deleteRecord(long id) {
SQLiteDatabase db = this.getWritableDatabase();
return (db.delete(TABLE_RECORDS,KEY_ID + "=?",new String[]{Long.toString(id)})> 0);
}
b）（i） onCLickListener 修正案（注意包括将所有删除分组到单个交易中）： -
// <<<<< DO IT BUTTON HANDLER i.e. get list of ID's for checked items
mDoItButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// get the ID's for the checked Items
mCheckedIdList = mMCA.getCheckedRecordIdList();
Toast.makeText(mContext,"You have " + mCheckedIdList.length + " Items checked.",Toast.LENGTH_SHORT).show();
//<<<< to delete
SQLiteDatabase db = mDBHandler.getWritableDatabase();
db.beginTransaction();
for (long id: mCheckedIdList) {
mDBHandler.deleteRecord(id);
}
db.setTransactionSuccessful();
db.endTransaction();
refreshListView();
}
});
b（ii）更新 Listview （活动中的新方法）： -
private void refreshListView() {
mCsr = mDBHandler.getAllRecords();
mMCA.swapCursor(mCsr);
}
备注
修改后的自定义光标适配器应为： -
public class MyCustomCursorAdapter extends CursorAdapter {
private Context mContext;
private String[] mColumns;
private int[] mViews;
private int mLayout;
private boolean[] mCheckBoxStates;
private int mCheckBoxView;
// Constructor for the Custom Cursor Adapter
MyCustomCursorAdapter(Context context, int layout, Cursor csr, String[] from_columns, int[] to_views, int checkbox_view) {
super(context,csr, false);
mContext = context;
mLayout = layout;
mColumns = from_columns;
mViews = to_views;
mCheckBoxView = checkbox_view;
}
@Override
// Inflate the layout we are going to use (as passed via 2nd parameter)
public View newView(Context context, Cursor csr, ViewGroup parent) {
// Initialise an int array for the checkboxes (all will be 0)
mCheckBoxStates = new boolean[csr.getCount()];
return LayoutInflater.from(context).inflate(mLayout,parent,false);
}
@Override
// Tie the from_columns to the display views
public void bindView(View view, Context context, Cursor csr) {
final Cursor fcsr = csr;
// Place the data from the cursor into the respective View (TextView)
for (int i = 0; i < mColumns.length; i++) {
((TextView) view.findViewById(mViews[i])).setText(csr.getString(csr.getColumnIndex(mColumns[i])));
}
// Set the checkbox (note should be false, unless otherwise changed)
CheckBox currentCheckBox = (CheckBox) view.findViewById(mCheckBoxView);
currentCheckBox.setChecked(mCheckBoxStates[csr.getPosition()]);
currentCheckBox.setTag(new Long(csr.getLong(csr.getColumnIndex(DatabaseHandler.KEY_ID))));
//
currentCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
final int position = fcsr.getPosition();
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// Store the checkbox status
mCheckBoxStates[position] = ((CheckBox) buttonView).isChecked();
int restore_cursor_position = fcsr.getPosition();
//Move the Cursor to the respective row
//NOTE! 1st position in Lisview is 1 but equates to cursor row 0 etc hence -1
fcsr.moveToPosition(position);
Toast.makeText(mContext,
"You Changed the CheckBox for row " +
Integer.toString(position + 1) +
" Item is " +
fcsr.getString(fcsr.getColumnIndex(DatabaseHandler.KEY_ITEM))
,
Toast.LENGTH_SHORT
).show();
//restore the Cursor's position
fcsr.moveToPosition(restore_cursor_position);
}
});
}
// get the list of items (the ID's as long) that have been checked.
public long[] getCheckedRecordIdList() {
Cursor csr = this.getCursor();
// using ArrayList as we can add as we don't yet know how many
ArrayList<Long> rva = new ArrayList<>();
// Just in case save the current position of the Cursor
int restore_cursor_position = csr.getPosition();
// Loop through the checkbox states
for (int i=0; i < mCheckBoxStates.length; i++) {
// If the checkbox reflected as being checked then handle, else ignore it
if (mCheckBoxStates[i]) {
// Move to the respective cursor row
csr.moveToPosition(i);
// get the respective ID and store in the arraylist
rva.add(csr.getLong(csr.getColumnIndex(DatabaseHandler.KEY_ID)));
}
}
// Done with the Cursor so re-position it
csr.moveToPosition(restore_cursor_position);
// Create the long array to be returned
long[] rv = new long[rva.size()];
// Populate the long array with the id's from the arraylist
for (int i=0; i < rva.size(); i++) {
rv[i] = rva.get(i);
}
// return the long[]
return rv;
}
@Override
public Cursor swapCursor(Cursor csr) {
mCheckBoxStates = new boolean[csr.getCount()];
for (int i=0; i < mCheckBoxStates.length; i++) {
mCheckBoxStates[i] = false;
}
return super.swapCursor(csr);
}
}