我尝试从片段活动中调用一个方法。
public class FragmentHome extends Fragment {
private String DATABASE_NAME = "Alarm.sqlite";
private SQLiteDatabase Database;
ListView listView;
ArrayList<alarm> list;
AdapterAlarm adapterAlarm;
Intent intent;
AlarmManager alarmManager;
PendingIntent pendingIntent;
Switch aSwitch;
@RequiresApi(api = Build.VERSION_CODES.M)
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_fragment_home, container, false);
listView = (ListView)view.findViewById(R.id.lv);
//khoi tao arraylist va adapter
list = new ArrayList<alarm>();
adapterAlarm = new AdapterAlarm(list, getActivity());
//set adapter len listview
listView.setAdapter(adapterAlarm);
//đăng ký context menu
registerForContextMenu(view.findViewById(R.id.lv));
return view;
}
@Override
public void onStart() {
super.onStart();
getData();
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
this.getActivity().getMenuInflater().inflate(R.menu.menu_listview_home, menu);
}
@Override
public boolean onContextItemSelected(MenuItem item) {
AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
alarm al = list.get(info.position);
int id = al.getId();
switch(item.getItemId()) {
case R.id.edit:
//sửa báo thức
Intent in = new Intent(getActivity(), EditActivity.class);
Bundle b = new Bundle();
b.putInt("Id", id);
in.putExtra("data", b);
startActivity(in);
break;
case R.id.delete:
//xóa báo thức
deleteItem(id);
break;
}
return true;
}
public void getData(){
//doc du lieu tu db len arraylist
Database = database.initDatabase(getActivity(), DATABASE_NAME);
Cursor cursor = Database.rawQuery("SELECT*FROM Alarm", null);
list.clear();
for(int i=0; i<cursor.getCount(); i++) {
//di chuyển cursor đến vị trí thứ i
cursor.moveToPosition(i);
//thêm đối tượng vào list
list.add(new alarm(cursor.getInt(0), cursor.getString(1), cursor.getString(2)
, cursor.getInt(3), cursor.getInt(4), cursor.getInt(5)));
//Lấy giờ từ db ra, tách giờ, phút
alarm al = list.get(i);
int hour = 0, minute=0;
for (int j=0; j<al.getTime().length(); j++){
//lấy giờ
String ch1 = String.valueOf(al.getTime().charAt(0));
String ch2 = String.valueOf(al.getTime().charAt(1));
String t;
if(ch2.equals(":")){
t = ch1;
}else{
t=ch1+ch2;
}
hour = Integer.parseInt(t);
//lấy phút
String ch3 = String.valueOf(al.getTime().charAt(3));
String ch4 = String.valueOf(al.getTime().charAt(4));
//kiem tra neu so cuoi cung cua minute la " " thi chi lay ki tu thu 3
String m;
if(ch4.equals(" ")){
m =ch3;
}else{
m =ch3+ch4;
}
minute = Integer.parseInt(m);
}
if(cursor.getInt(5)==1){
setAlarm(hour, minute, getActivity());
}
}
//bat su kien khi co thay doi du lieu tren adapter
adapterAlarm.notifyDataSetChanged();
}
public void setAlarm(int hour, int minute, Context context){
//khởi tạo đối tượng calender
Calendar calendar = Calendar.getInstance();
//lấy giờ hiện tại của hệ thống
calendar.setTimeInMillis(System.currentTimeMillis());
//đặt giờ báo thức
calendar.set(Calendar.HOUR_OF_DAY, hour);
calendar.set(Calendar.MINUTE, minute);
calendar.set(Calendar.SECOND, 0);
//khởi tạo intent
intent = new Intent(getContext(), Alarm_Receiver.class);
intent.putExtra("extra", "yes");
//khởi tạo đối tượng pending intent
pendingIntent = PendingIntent.getBroadcast(getContext(), 0, intent, 0);
//khởi tạo đối tường alarmmanager
alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
//đặt báo thức lặp lại hằng ngày
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP,calendar.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);
}
public void cancelAlarm(){
if(alarmManager!=null){
intent.putExtra("extra", "no");
alarmManager.cancel(pendingIntent);
getActivity().sendBroadcast(intent);
}
}
private void deleteItem(final int id){
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Confirm");
builder.setMessage("Are you sure, Do you want delete?");
builder.setNegativeButton("No", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
dialog.dismiss();
}
});
builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
// TODO Auto-generated method stub
Database = database.initDatabase(getActivity(), DATABASE_NAME);
Database.delete("Alarm", "ID = ?", new String[]{id+""});
//doc lại dữ liệu cho listview
Database = database.initDatabase(getActivity(), DATABASE_NAME);
Cursor cursor = Database.rawQuery("SELECT*FROM Alarm", null);
list.clear();
for(int i=0; i<cursor.getCount(); i++){
//di chuyển cursor đến vị trí thứ i
cursor.moveToPosition(i);
//thêm đối tượng vào list
list.add(new alarm(cursor.getInt(0), cursor.getString(1), cursor.getString(2)
, cursor.getInt(3), cursor.getInt(4), cursor.getInt(5)));
}
//bat su kien khi co thay doi du lieu tren adapter
adapterAlarm.notifyDataSetChanged();
Toast.makeText(getActivity(), "Delete sucessfully!", Toast.LENGTH_SHORT).show();
}
});
builder.setIcon(R.drawable.logo);
builder.create().show();
}
@Override
public void onResume() {
super.onResume();
}
}
我尝试在另一项活动
中从cancelAlarm()调用方法FragmentHome
FragmentHome fh = new FragmentHome();
fh.cancelAlarm();
但它不起作用？
答案 0 :(得分：0)
看起来问题是你永远不会初始化alarmManager变量，所以当这个代码被命中时它是null，所以没有任何反应。
public void cancelAlarm(){
if(alarmManager!=null){ ...
根据你的代码，你似乎必须在调用cancelAlarm（）之前调用setAlarm（）。
尝试类似：
FragmentHome fh = new FragmentHome();
fh.setAlarm(12, 30, this);
fh.cancelAlarm();
我建议花点时间学习设置断点并在调试模式下运行应用程序。像这样的错误很容易被发现。