我需要从SQLite数据库中获取对象,并在ListView中显示它们。此外,每个对象在视图上必须具有2个按钮:“编辑”和“删除”。这是适配器的代码:
public class ReminderListAdapter extends ArrayAdapter<Reminder> {
private Context mContext;
private int mResource;
public ReminderListAdapter(@NonNull Context context, int resource, @NonNull ArrayList<Reminder> objects) {
super(context, resource, objects);
mContext = context;
mResource = resource;
}
@NonNull
@Override
public View getView(final int position, @Nullable View convertView, @NonNull ViewGroup parent) {
final int id = getItem(position).getId();
final String name = getItem(position).getName();
String hour = getItem(position).getHour();
String date = getItem(position).getDate();
LayoutInflater inflater = LayoutInflater.from(mContext);
convertView = inflater.inflate(mResource, parent, false);
final TextView resId = convertView.findViewById(R.id.textId);
final TextView resName = convertView.findViewById(R.id.textName);
final TextView resHour = convertView.findViewById(R.id.textHour);
final TextView resDate = convertView.findViewById(R.id.textDate);
resId.setText(String.valueOf(id));
resName.setText(name);
resHour.setText(hour);
resDate.setText(date);
Button delbtn = (Button) convertView.findViewById(R.id.button4);
Button editbtn = (Button) convertView.findViewById(R.id.button5);
delbtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
editbtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
return convertView;
}
/*public boolean delete_Reminder(String name2){
return database.delete(TABLE_REMINDERS, KEY_NAME + "=" + name2, null) > 0;
}*/}
这是我需要发布对象的活动代码:
public class EditActivity extends AppCompatActivity {
DBHelper dbHelper;
SQLiteDatabase database;
private ListView listView;
ArrayList<Reminder> ReminderList = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_edit);
dbHelper = new DBHelper(this);
database = dbHelper.getWritableDatabase();
listView =(ListView) findViewById(R.id.ListOfReminders);
Cursor cursor = database.query(TABLE_REMINDERS, null, null,null,null,null,null);
if(cursor.moveToFirst())
{
do{
int idIndex = cursor.getInt(cursor.getColumnIndex(DBHelper.KEY_ID));
String nameIndex = cursor.getString(cursor.getColumnIndex(DBHelper.KEY_NAME));
String hourIndex = cursor.getString(cursor.getColumnIndex(DBHelper.KEY_HOUR));
String dateIndex = cursor.getString(cursor.getColumnIndex(DBHelper.KEY_DATE));
String name = nameIndex;
String hour = hourIndex;
String date = dateIndex;
ReminderList.add(new Reminder(idIndex, name, hour, date));
ReminderListAdapter adapter = new ReminderListAdapter(this, R.layout.reminder_view, ReminderList);
listView.setAdapter(adapter);
} while(cursor.moveToNext());
} else
Log.d("mLog", "0 rows in db");
dbHelper.close();
}
public boolean delete_Reminder(String name2){
return database.delete(TABLE_REMINDERS, KEY_NAME + "=" + name2, null) > 0;
}}
在hinter_layout中,我有这些按钮。
我想我需要在我的适配器中实现这两个按钮。在代码中,您可以看到delbtn和editbtn的onClickListener。但是我的问题是我不知道如何调用方法delete_Reminder(它也在Adapter中),因为我不能在这里创建DBHelper,也无法连接到DB。抱歉,这是一个愚蠢的问题,它是第一个应用程序。
使用interface
进行回调。活动与适配器之间的桥接接口;一旦用户在Adapter的视图上执行操作,请给Activity回调。
接口
interface OnItemClickListener {
void onItemClick(View view, int position, String name)
}
活动
public class EditActivity extends AppCompatActivity implements
OnItemClickListener {
...
@Override
protected void onCreate(Bundle savedInstanceState) {
...
ReminderListAdapter adapter = new ReminderListAdapter(this, R.layout.reminder_view, ReminderList);
listView.setListener(this);
listView.setAdapter(adapter);
...
}
@Override
public void onItemClick(final View view, final int position, final String name) {
//Your callback
delete_Reminder(name);
}
}
适配器
public class ReminderListAdapter extends ArrayAdapter<Reminder> {
private Context mContext;
private int mResource;
private final OnItemClickListener listener;
public ReminderListAdapter(@NonNull Context context, int resource,
@NonNull ArrayList<Reminder> objects) {
super(context, resource, objects);
mContext = context;
mResource = resource;
}
public setListener(final OnItemClickListener listener) {
this.listener = listener;
}
...
@NonNull
@Override
public View getView(final int position, @Nullable View convertView, @NonNull ViewGroup parent) {
...
delbtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
listener.onItemClick(v, vh.getAdapterPosition(), name);
}
});
}
}