null pointer exception in getView when handling onClick event

Question

    @Override
public View getView(int position, View convertView, ViewGroup parent) {
    View view;
    ViewHolder holder;

    if (null == convertView) {
        view = inflater.inflate(R.layout.web_courses_list_item, null);
        // Set table view color for each new row
        view.setBackgroundColor(0xFFF0F0F0);

        // Create the view holder
        holder = new ViewHolder();
        holder.CourseName = (TextView) view.findViewById(R.id.course_name);
        holder.CourseDesc = (TextView) view.findViewById(R.id.course_desc);
        holder.DltButton = (Button) view.findViewById(R.id.btn_remove);
        final int pos = position;
        holder.DltButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(final View v) {
                if(v==null) {
                    Log.v("RemoveCheck", "view v is null");
                    return;
                }
                Builder builder = new Builder(mContext);
                builder.setTitle("Alert!!!!");
                builder.setMessage("Are you sure you want to delete "+mCoursesList.get(pos).getName());
                builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        mCoursesList.get(pos).setVisible(false);
                        mCoursesList.remove(pos);
                        v.setVisibility(View.GONE);
                        CoursesChangeData(mCoursesList);
                    }
                });

                builder.setNegativeButton("No", new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                    }
                });

                builder.create().show();
            }
        });
        view.setTag(holder);
    } else {
        view = convertView;
        holder = (ViewHolder) view.getTag();
    }

    CourseData current = mCoursesList.get(position);
    holder.CourseName.setText(current.getName());
    holder.CourseDesc.setText(current.getDesc());
    if (mCoursesList.get(position).isVisible())
        holder.DltButton.setVisibility(View.VISIBLE);
    else
        holder.DltButton.setVisibility(View.GONE);
    return view;
}

Hey guys, I implemented this method of baseAdapter for handling clicking on the delete button. the delete button is invisible until a swipe on listView item, which makes it visible, when i touch on delete its crashing and here is the callstack (The error is from the line builder.create().show(); ; this is line 111):

05-17 21:56:15.579: E/AndroidRuntime(18584): FATAL EXCEPTION: main
05-17 21:56:15.579: E/AndroidRuntime(18584): Process: com.example.webcourse, PID: 18584
05-17 21:56:15.579: E/AndroidRuntime(18584): android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.view.ViewRootImpl.setView(ViewRootImpl.java:540)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:259)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.app.Dialog.show(Dialog.java:286)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at com.example.webcourse.CoursesListAdapter$1.onClick(CoursesListAdapter.java:111)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.view.View.performClick(View.java:4445)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.view.View$PerformClick.run(View.java:18429)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.os.Handler.handleCallback(Handler.java:733)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.os.Handler.dispatchMessage(Handler.java:95)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.os.Looper.loop(Looper.java:136)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at android.app.ActivityThread.main(ActivityThread.java:5081)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at java.lang.reflect.Method.invokeNative(Native Method)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at java.lang.reflect.Method.invoke(Method.java:515)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:781)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-17 21:56:15.579: E/AndroidRuntime(18584):    at dalvik.system.NativeStart.main(Native Method)
05-17 21:56:15.584: W/ActivityManager(2330):   Force finishing activity com.example.webcourse/.CoursesActivity

If you are trying to cast an object to an int many stuff happen. Read the docs — user3535778, May 17 '14 at 18:34

score 1 · Answer 1 · answered May 17 '14 at 18:31

1

you are setting ViewHolder as tag to the view. But when you are calling getTag, it is type casted to int, which is the issue. It cannot be int and so the exception.

answered May 17 '14 at 18:31

essess

277
3
7

check out the edited version, what is the problem now? – Shmulik Chicvashvili May 17 '14 at 19:05
change the line - Builder builder = new Builder(mContext); to Builder builder = new Builder(this); – essess May 17 '14 at 19:22
The constructor AlertDialog.Builder(new View.OnClickListener(){}) is undefined – Shmulik Chicvashvili May 17 '14 at 19:34

score 0 · Answer 2 · answered May 18 '14 at 20:52

0

You can't know if context is final or not. You should use: v.getContext()

answered May 18 '14 at 20:52

CodeMonkey

11,196
30
112
203

score 0 · Answer 3 · edited May 23 '17 at 10:32

0

You cant set view.gone, view is reused for other elements. After changing the data set, you need to invalidate the adapter. Because you remove the object from the list and dont invalidate, the adapter will try to access the last element, which causes the null pnt exception.

Check this thread Updating the list view when the adapter data changes

edited May 23 '17 at 10:32

Community

1
1

answered May 18 '14 at 22:33

Dror

1

null pointer exception in getView when handling onClick event

3 Answers3