所以我有一个 ListView 和一个自定义适配器，我正在向数据库添加值，然后重新填充列表，所以我以以下方式添加项目：q、w、e、r、t、y、u、i、o、 p 列表视图填充如下：q,w,e,r,t,y,q,q,q
这是自定义适配器
public class TestListAdapter extends BaseAdapter {
private static ArrayList<FlashCard> flashCardItems;
private LayoutInflater mInflater;
private Context context;
public TestListAdapter(Context context, ArrayList<FlashCard> results) {
this.context = context;
flashCardItems = results;
mInflater = LayoutInflater.from(context);
}
public int getCount() {
return flashCardItems.size();
}
public Object getItem(int position) {
return flashCardItems.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.flashcard, null);
holder = new ViewHolder();
holder.flipper = (ViewFlipper) convertView.findViewById(R.id.flashcard);
convertView.setTag(holder);
}
else {
holder = (ViewHolder) convertView.getTag();
}
holder.flipper.addView(FlashCard.createQuestionCard(context,flashCardItems.get(position).getQuestion()));
return convertView;
}
static class ViewHolder {
ViewFlipper flipper;
}
}
这是数据库处理程序
public class DatabaseHandler extends SQLiteOpenHelper {
// All Static variables
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "mySchoolDB";
// Flashcards table name
private static final String TABLE_FLASHCARDS = "flashcards";
// Flashcards Table Columns names
private static final String KEY_ID = "id";
private static final String QUESTION = "question";
private static final String ANSWER = "answer";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
String CREATE_FLASHCARDS_TABLE = "CREATE TABLE " + TABLE_FLASHCARDS + "("
+ KEY_ID + " INTEGER PRIMARY KEY," + QUESTION + " TEXT,"
+ ANSWER + " TEXT" + ")";
db.execSQL(CREATE_FLASHCARDS_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_FLASHCARDS);
// Create tables again
onCreate(db);
}
/**
* All CRUD(Create, Read, Update, Delete) Operations
*/
// Adding new Flashcard
public void addFlashcard(FlashCard flashcard) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(QUESTION, flashcard.getQuestion()); // flashcard Name
values.put(ANSWER, flashcard.getAnswer()); // flashcard Phone
// Inserting Row
db.insert(TABLE_FLASHCARDS, null, values);
db.close(); // Closing database connection
}
// Getting single FlashCard
public FlashCard getFlashcard(int id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_FLASHCARDS, new String[] { KEY_ID,
QUESTION, ANSWER }, KEY_ID + "=?",
new String[] { String.valueOf(id) }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
FlashCard flashcard= new FlashCard(Integer.parseInt(cursor.getString(0)),
cursor.getString(1), cursor.getString(2));
cursor.close();
db.close();
// return FlashCard
return flashcard;
}
// Getting All Flashcards
public ArrayList<FlashCard> getAllFlashcards() {
ArrayList<FlashCard> FlashcardList = new ArrayList<FlashCard>();
// Select All Query
String selectQuery = "SELECT * FROM " + TABLE_FLASHCARDS;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
FlashCard flashcard = new FlashCard(Integer.parseInt(cursor.getString(0)),cursor.getString(1),cursor.getString(2));
// Adding Flashcard to list
FlashcardList.add(flashcard);
} while (cursor.moveToNext());
}
cursor.close();
db.close();
// return Flashcard list
return FlashcardList;
}
// Updating single Flashcard
public int updateFlashcard(FlashCard flashcard) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(QUESTION, flashcard.getQuestion());
values.put(ANSWER, flashcard.getAnswer());
db.close();
// updating row
return db.update(TABLE_FLASHCARDS, values, KEY_ID + " = ?",
new String[] { String.valueOf(flashcard.getID()) });
}
// Deleting single Flashcard
public void deleteFlashcard(FlashCard flashcard) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_FLASHCARDS, KEY_ID + " = ?",
new String[] { String.valueOf(flashcard.getID()) });
db.close();
}
// Getting Flashcards Count
public int getFlashcardsCount() {
String countQuery = "SELECT * FROM " + TABLE_FLASHCARDS;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
cursor.close();
// return count
return cursor.getCount();
}
public void deleteAllFlashCards(){
SQLiteDatabase sdb= this.getWritableDatabase();
sdb.delete(TABLE_FLASHCARDS, null, null);
sdb.close();
}
}
这是列表视图
public class TestList extends ListView
{
private Context context;
private ArrayList<FlashCard> stringArray = new ArrayList<FlashCard>();
public TestList(Context context) {
super(context);
this.context = context;
setResults();
}
public void setResults() {
DatabaseHandler db = new DatabaseHandler(context);
stringArray = db.getAllFlashcards();
setAdapter(new TestListAdapter(context, stringArray));
}
public TestList(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public void addFlashCardDialog() {
final AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle("Add flashcard");
final EditText question = new EditText(context);
question.setHint("Question");
final EditText answer = new EditText(context);
answer.setHint("Answer");
LinearLayout qa = new LinearLayout(context);
qa.setOrientation(LinearLayout.VERTICAL);
qa.addView(question);
qa.addView(answer);
builder.setView(qa);
builder.setPositiveButton("Add", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
FlashCard f = new FlashCard(question.getText().toString(), answer.getText().toString());
DatabaseHandler db = new DatabaseHandler(context);
db.addFlashcard(f);
setResults();
}
});
builder.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
builder.show();
}
}