Android - Cannot create ListView within custom Dialog

Question

With my app, what happens is that when a user clicks a certain button, the custom dialog displays. The custom dialog consists of two widgets:

Edit Text field
ListView

This is supposed to work similar to how autocomplete would work. When the user has entered a certain number of characters (3) or more, I want to display a filtered ListView of the results. I get the text value from the EditText and I use it in an SQLite statement (works fine). I then add it to an ArrayList (no problem), but when I try and set the ArrayAdapter, I get the following message:

    08-11 11:49:20.552 8045-8045/com.example.maindec.sme E/AndroidRuntime: FATAL EXCEPTION: main
                                                                       Process: com.example.maindec.sme, PID: 8045
                                                                       java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
                                                                           at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:401)
                                                                           at android.widget.ArrayAdapter.getView(ArrayAdapter.java:369)
                                                                           at android.widget.AbsListView.obtainView(AbsListView.java:2346)
                                                                           at android.widget.ListView.makeAndAddView(ListView.java:1875)
                                                                           at android.widget.ListView.fillDown(ListView.java:702)
                                                                           at android.widget.ListView.fillFromTop(ListView.java:763)
                                                                           at android.widget.ListView.layoutChildren(ListView.java:1684)
                                                                           at android.widget.AbsListView.onLayout(AbsListView.java:2148)
                                                                           at android.view.View.layout(View.java:16630)
                                                                           at android.view.ViewGroup.layout(ViewGroup.java:5437)
                                                                           at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
                                                                           at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
                                                                           at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
                                                                           at android.view.View.layout(View.java:16630)
                                                                           at android.view.ViewGroup.layout(ViewGroup.java:5437)
                                                                           at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
                                                                           at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
                                                                           at android.view.View.layout(View.java:16630)
                                                                           at android.view.ViewGroup.layout(ViewGroup.java:5437)
                                                                           at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
                                                                           at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
                                                                           at android.view.View.layout(View.java:16630)
                                                                           at android.view.ViewGroup.layout(ViewGroup.java:5437)
                                                                           at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
                                                                           at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
                                                                           at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
                                                                           at android.view.View.layout(View.java:16630)
                                                                           at android.view.ViewGroup.layout(ViewGroup.java:5437)
                                                                           at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
                                                                           at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
                                                                           at android.view.View.layout(View.java:16630)
                                                                           at android.view.ViewGroup.layout(ViewGroup.java:5437)
                                                                           at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
                                                                           at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
                                                                           at android.view.View.layout(View.java:16630)
                                                                           at android.view.ViewGroup.layout(ViewGroup.java:5437)
                                                                           at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
                                                                           at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
                                                                           at com.android.internal.policy.PhoneWindow$DecorView.onLayout(PhoneWindow.java:2678)
                                                                           at android.view.View.layout(View.java:16630)
                                                                           at android.view.ViewGroup.layout(ViewGroup.java:5437)
                                                                           at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2171)
                                                                           at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1931)
                                                                           at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
                                                                           at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013)
                                                                           at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
                                                                           at android.view.Choreographer.doCallbacks(Choreographer.java:670)
                                                                           at android.view.Choreographer.doFrame(Choreographer.java:606)
                                                                           at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
                                                                           at android.os.Handler.handleCallback(Handler.java:739)
                                                                           at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                           at android.os.Looper.loop(Looper.java:148)
                                                                           at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                           at java.lang.reflect.Method.invoke(Native Method)
                                                                           at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
08-11 11:52:36.596 8045-8053/com.example.maindec.sme W/art: Suspending all threads took: 5.267ms
08-11 11:54:20.640 8045-8045/com.example.maindec.sme I/Process: Sending signal. PID: 8045 SIG: 9

That message only display when I try to set the adapter. I've debugged and this is definitely the problem.

Here's my code:

final AlertDialog.Builder builder = new AlertDialog.Builder(this);

    builder.setTitle("Smoke weed everyday...");

    builder.setPositiveButton("Try Again", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int id) {
        }
    })
            .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    //dialog.cancel();
                }
            });


    builder.setView(getLayoutInflater().inflate(R.layout.item_list_dialog, null));



   final Dialog dialog = builder.create();

// THIS IS THE NAME OF THE BUTTON
itemListSelection.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                dialog.setCanceledOnTouchOutside(false);

                dialog.show();

                final EditText itemNumberInputField = (EditText) dialog.findViewById(R.id.item_number_input_field);

                final ListView filteredItemNumberList = (ListView) dialog.findViewById(R.id.item_number_list);

                itemNumberInputField.addTextChangedListener(new TextWatcher() {
                    @Override
                    public void beforeTextChanged(CharSequence s, int start, int count, int after) {

                    }

                    @Override
                    public void onTextChanged(CharSequence s, int start, int before, int count) {
                        currentValue = itemNumberInputField.getText().toString();

                        smeDatabase = openOrCreateDatabase("SME", MODE_PRIVATE, null);
                        if (currentValue.length() > 2) {
                            keyNumbersList.clear();
                             Cursor itemResultSet = smeDatabase.rawQuery("SELECT * " +
                                    "FROM item_list", null);

                            for (int i = 0; i < itemResultSet.getCount(); i++) {
                                itemResultSet.moveToPosition(i);
                                keyNumbersList.add(itemResultSet.getString(0));
                                System.out.println("Test: " + itemResultSet.getString(0));
                            }
                            ArrayAdapter<String> itemNumbersAdapter = new ArrayAdapter<String>(NewKeyNumber.this, android.R.layout.simple_list_item_1, keyNumbersList);
        //THIS IS THE LINE THAT FAILS            filteredItemNumberList.setAdapter(itemNumbersAdapter); 
                        }
                    }

                    @Override
                    public void afterTextChanged(Editable s) {

                    }

                });
            }
        });

Any help with this would be appreciated. Thanks.

add full logcat its not enough? – Sohail Zahid Aug 11 '16 at 12:35 — Sohail Zahid, Aug 11 '16 at 12:35

score 0 · Answer 1 · answered Aug 11 '16 at 14:02

0

You shouldn't iterate a cursor with for and get manually the item position.

You can use:

  if(cursor.moveToFirst()){
           do {
               String value= cursor.getString(0);
           }while (cursor.moveToNext());
        }
        cursor.close();

Also, define

itemNumbersAdapter as a global variable.

And

ArrayAdapter<String> itemNumbersAdapter = new ArrayAdapter<String>(NewKeyNumber.this, android.R.layout.simple_list_item_1, keyNumbersList);

An then only change keyNumbersList data. after change keyNumbersList data you have to call itemNumbersAdapter.notifyDataSetChanged();

answered Aug 11 '16 at 14:02

Andres Vasquez Agramont

359
2
9

Can post an example, editing my coding and inserting your code into it? I'm stll getting this .toString() on a null object reference. – Chosen1 Aug 11 '16 at 15:23
Do you mind upvoting my question? I don't understand why they are all getting downvotes. – Chosen1 Aug 15 '16 at 12:20

score 0 · Accepted Answer · answered Aug 15 '16 at 12:18

It turned out that the reason why it kept failing was because I had a null value inside my ArrayList, so I did this to solve it:

if (currentItem != null) {
          keyNumbersList.add(itemResultSet.getString(0));
          System.out.println("Test: " + itemResultSet.getString(0));
}

Filtering out any null values. Works great.

Android - Cannot create ListView within custom Dialog

2 Answers2