我在书中使用了很多关于如何处理数据库并将数据保存到sql的代码。我是一个绝对的初学者。 我现在正在尝试更新长时间点击的行，但到目前为止还没有好处，我找不到从数据库中获取所点击行的正确ID的方法。我了解到我应该将视图中的数据绑定到数据库中的数据，但我不知道如何执行此操作。如果有人能帮助我，我将非常感激。
现在我已经获得了一些代码。这是MyDB类：
public class MyDB {
private static final String TABLE_NAME = null;
private static final String KEY_ID = null;
private SQLiteDatabase db;
private final Context context;
private final MyDBhelper dbhelper;
// Initializes MyDBHelper instance
public MyDB(Context c){
context = c;
dbhelper = new MyDBhelper(context, Constants.DATABASE_NAME, null,
Constants.DATABASE_VERSION);
}
// Closes the database connection
public void close()
{
db.close();
}
// Initializes a SQLiteDatabase instance using MyDBhelper
public void open() throws SQLiteException
{
try {
db = dbhelper.getWritableDatabase();
} catch(SQLiteException ex) {
Log.v("Open database exception caught", ex.getMessage());
db = dbhelper.getReadableDatabase();
}
}
// updates a diary entry (existing row)
public boolean updateDiaryEntry(String title, long rowId)
{
ContentValues newValue = new ContentValues();
newValue.put(Constants.TITLE_NAME, title);
return db.update(Constants.TABLE_NAME, newValue, Constants.KEY_ID + "=" + rowId, null)>0;
}
// Reads the diary entries from database, saves them in a Cursor class and returns it from the method
public Cursor getdiaries()
{
Cursor c = db.query(Constants.TABLE_NAME, null, null,
null, null, null, null);
return c;
}
}
这是我的EditListItemDialog，它扩展了Dialog：
class EditListItemDialog extends Dialog implements View.OnClickListener {
MyDB dba;
private View editText;
private DiaryAdapter adapter;
private SQLiteDatabase db;
public EditListItemDialog(Context context) {
super(context);
dba = new MyDB(context);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.edit_text_dialog);//here is your xml with EditText and 'Ok' and 'Cancel' buttons
View btnOk = findViewById(R.id.button_ok);
editText = findViewById(R.id.edit_text);
btnOk.setOnClickListener(this);
dba.open();
}
private List<String> fragment_monday;
private long rowId;
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//Position is the number of the item clicked
//You can use your adapter to modify the item
long rowId = adapter.getItemId(position); //Will return the clicked item
saveItToDB(rowId);
}
public EditListItemDialog(Context context, DiaryAdapter adapter, int position) {
super(context);
this.fragment_monday = new ArrayList<String>();
this.adapter = adapter;
dba = new MyDB(context);
}
@Override
public void onClick(View v) {
fragment_monday.add(((TextView) v).getText().toString());//here is your updated(or not updated) text
// public void notifyDataSetChanged();
dismiss();
try {
saveItToDB(rowId);
} catch (Exception e) {
e.printStackTrace();
}
}
private void saveItToDB(long rowId) {
dba.open();
dba.updateDiaryEntry(((TextView) editText).getText().toString(), rowId);
dba.close();
((TextView) editText).setText("");
}
}
这里是带有日记适配器的类，它扩展了基本适配器：
public class Monday extends ListActivity {
private SQLiteDatabase db;
private static final int MyMenu = 0;
MyDB dba;
DiaryAdapter myAdapter;
private class MyDiary{
public MyDiary(String t, String c){
title=t;
content=c;
}
public String title;
public String content;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
dba = new MyDB(this);
dba.open();
setContentView(R.layout.fragment_monday);
super.onCreate(savedInstanceState);
myAdapter = new DiaryAdapter(this);
this.setListAdapter(myAdapter);
}
public class DiaryAdapter extends BaseAdapter {
private LayoutInflater mInflater;
private ArrayList<MyDiary> fragment_monday;
public DiaryAdapter(Context context) {
mInflater = LayoutInflater.from(context);
fragment_monday = new ArrayList<MyDiary>();
getdata();
ListView list = getListView();
list.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
new EditListItemDialog(Monday.this, null, position).show();
return true;
}
});
}
public void getdata(){
Cursor c = dba.getdiaries();
startManagingCursor(c);
if(c.moveToFirst()){
do{
String title =
c.getString(c.getColumnIndex(Constants.TITLE_NAME));
String content =
c.getString(c.getColumnIndex(Constants.CONTENT_NAME));
MyDiary temp = new MyDiary(title,content);
fragment_monday.add(temp);
} while(c.moveToNext());
}
}
@Override
public int getCount() {return fragment_monday.size();}
public MyDiary getItem(int i) {return fragment_monday.get(i);}
public long getItemId(int i) {return i;}
public View getView(int arg0, View arg1, ViewGroup arg2) {
final ViewHolder holder;
View v = arg1;
if ((v == null) || (v.getTag() == null)) {
v = mInflater.inflate(R.layout.diaryrow, null);
holder = new ViewHolder();
holder.mTitle = (TextView)v.findViewById(R.id.name);
v.setTag(holder);
} else {
holder = (ViewHolder) v.getTag();
}
holder.mdiary = getItem(arg0);
holder.mTitle.setText(holder.mdiary.title);
v.setTag(holder);
return v;
}
public class ViewHolder {
MyDiary mdiary;
TextView mTitle;
}
}
/** Called when the user clicks the Edit button */
public void visitDiary(View view) {
Intent intent = new Intent(this, Diary.class);
startActivity(intent);
}
/** Called when the user clicks the back button */
public void visitSchedule(View view) {
Intent intent = new Intent(this, DisplayScheduleScreen.class);
startActivity(intent);
}
}