NullPointerException when use findViewById() in AlertDialog.Builder

Question

This is my code

@Override
public void onClick(View v) {
final AlertDialog.Builder adb = new AlertDialog.Builder(getApplicationContext());
adb.setView(LayoutInflater.from(getApplicationContext()).inflate(R.layout.custom, null));

adb.setPositiveButton("Add",new android.content.DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int arg1) {

                DatePicker datePicker = (DatePicker)findViewById(R.id.datePicker);

                java.util.Date date = null;
                Calendar cal = GregorianCalendar.getInstance();
                cal.set(datePicker.getYear(),datePicker.getMonth(), datePicker.getDayOfMonth());
                date = cal.getTime();
            }                  
        });             
adb.show();
}

I have the NullPointerException in this line, and I think datePicker wasn't findById, because I use AlertDialog.Builder.

cal.set(datePicker.getYear(),datePicker.getMonth(), datePicker.getDayOfMonth());

I tried use adb.findViewById(); but it'is a mistake (The method findViewById(int) is undefined for the type AlertDialog.Builder). Can you help me, please?

score 15 · Accepted Answer · edited Jun 01 '16 at 20:12

15

Change

DatePicker datePicker = (DatePicker)findViewById(R.id.datePicker);

this line to

DatePicker datePicker = (DatePicker)adb.findViewById(R.id.datePicker);

...............

try this one:

final AlertDialog.Builder adb = new AlertDialog.Builder(this);
final View view = LayoutInflater.from(getApplicationContext()).inflate(R.layout.main1, null);
adb.setView(view);
final Dialog dialog;
adb.setPositiveButton("Add",new android.content.DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int arg1) {

        DatePicker datePicker = (DatePicker)view.findViewById(R.id.datePicker1);

        java.util.Date date = null;
        Calendar cal = GregorianCalendar.getInstance();
        cal.set(datePicker.getYear(),datePicker.getMonth(), datePicker.getDayOfMonth());
        date = cal.getTime();
    }                  
});   
dialog = adb.create();
dialog.show();

edited Jun 01 '16 at 20:12

OneCricketeer

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answered Oct 23 '12 at 08:24

Khawar Raza

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`The method findViewById(int) is undefined for the type AlertDialog.Builder` if I add to cast ((Dialog)adb).findViewById I have `Cannot cast from AlertDialog.Builder to Dialog` – pavelartlover Oct 23 '12 at 08:31
If don't works, why you accepted it? EDIT: Yeah, the second part is the one that works. Use the inflated layout instead of the dialog. – Jorge Fuentes González Jun 04 '13 at 17:54
The key for me was `view.findViewById(R.id.datePicker1);`, specifically that you used `view` rather than your `Activity` to call `findViewById()` – scottysseus Mar 14 '15 at 23:22
please, delete first example :) – Nammen8 Feb 08 '16 at 20:00

score 2 · Answer 2 · answered Oct 23 '12 at 08:22

2

Search for the DatePicker using the dialog parameter:

DatePicker datePicker = (DatePicker) ((Dialog) dialog).findViewById(R.id.datePicker);

answered Oct 23 '12 at 08:22

user

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Eclipse said `Cannot cast from AlertDialog.Builder to Dialog` – pavelartlover Oct 23 '12 at 08:26
@pavelartlover Did you use my **exact** code, with the `dialog` parameter from the `onClick` method and you get that `Cannot cast...`? – user Oct 23 '12 at 08:33
I replace your `dialog` by my `adb`. Maybe I use wrong type of dialog in this case. I want to show custom dialog with datepicker and other stuff from my xml file, and two button like in alert dialog - Save and Cancel. – pavelartlover Oct 23 '12 at 09:03
@pavelartlover Once again, use **exactly** what I said in my answer. – user Oct 23 '12 at 09:06

score 2 · Answer 3 · answered Jun 12 '14 at 06:01

I think this could be the problem,

final AlertDialog.Builder adb = new AlertDialog.Builder(getApplicationContext());
adb.setView(LayoutInflater.from(getApplicationContext()).inflate(R.layout.custom,null));

Use the below way to inflate the view and use the view object for getting the id.

 LayoutInflater factory = LayoutInflater.from(this);
    final View textEntryView = factory.inflate(R.layout.alert_dialog_text_entry, null);

DatePicker datePicker = (DatePicker)textEntryView.findViewById(R.id.datePicker1);

Example:

protected Dialog onCreateDialog() {
    LayoutInflater factory = LayoutInflater.from(this);
    final View textEntryView = factory.inflate(R.layout.alert_dialog_text_entry, null);
    return new AlertDialog.Builder(TicTacToe.this)
        //.setIconAttribute(android.R.attr.alertDialogIcon)
        .setTitle(getTitleText())
        .setView(textEntryView)
        .setPositiveButton("JOIN GAME", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int whichButton) {
                try
                {
                    EditText et = (EditText)findViewById(R.id.username_edit);
                        playerName = et.getText().toString();
                }
                catch (Exception e)
                {
                }
            }
        })
        .create();
return null;

}

yeah i forgot to inflate R.layout.xxx – Jemshit Mar 24 '15 at 16:43 — Jemshit, Mar 24 '15 at 16:43

score 0 · Answer 4 · answered Jun 15 '15 at 14:28

0

In my case: First I must call the

dialog.show(),

and only after it I was able to use

dialog.findviewById(R.id.myID).

If I missed to call the show(), than I got a null back with findViewByID.

answered Jun 15 '15 at 14:28

narancs

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score 0 · Answer 5 · answered Mar 25 '17 at 14:10

0

A project clean and rebuild fixed this error for me (on Xamarin).

answered Mar 25 '17 at 14:10

mvandillen

904
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NullPointerException when use findViewById() in AlertDialog.Builder

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