Question

I am using a list view with a custom adapter.I am getting a null pointer exception whose reason is unknown.I have even tried to debug it but the debugger is not able to locate the location of the exception.This is the code:

if(SplashActivity.s_contactNameArrayListSplash != null && SplashActivity.s_contactNameArrayListSplash.size() != 0)
        {
            if(m_contactAdapterSetTheRule  == null)
            {
                m_contactAdapterSetTheRule = new ContactAdapterSetRule(ShowTheContacts1.this, R.layout.showthecontacts, SplashActivity.s_contactNameArrayListSplash);

                //add the footer before adding the adapter, else the footer will not load!
                //  View footerView = ((LayoutInflater)this.getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.listfooter, null, false);
                View footerView  = getLayoutInflater().inflate(R.layout.listfooter, null);
                m_lvShowContactsSetTheRule.addFooterView(footerView);

                m_lvShowContactsSetTheRule.setAdapter(m_contactAdapterUpdatingRule);
            }


            m_lvShowContactsSetTheRule.setOnScrollListener(new OnScrollListener(){

                //useless here, skip!
                @Override
                public void onScrollStateChanged(AbsListView view, int scrollState) {}

                @Override
                public void onScroll(AbsListView view, int firstVisibleItem,
                        int visibleItemCount, int totalItemCount) {


                    //what is the bottom item that is visible
                    int lastInScreen = firstVisibleItem + visibleItemCount;             

                    //is the bottom item visible & not loading more already ? Load more !
                    if((lastInScreen == totalItemCount) && !(m_loadingMore)){                   
                        Thread thread =  new Thread(null, loadMoreListItems);
                        thread.start();
                    }
                }
            });


            //Load the first 25 items
            Thread thread =  new Thread(null, loadMoreListItems);
            thread.start();

        }
        else
        {
            Log.e("Info: ","No any contact present in the add Rule Array list");
            Toast.makeText(ShowTheContacts1.this,"No Contact is present in the contact list",Toast.LENGTH_LONG).show();
            Intent intent = new Intent(ShowTheContacts1.this,Settings.class);
            startActivity(intent);
        }       
    }
    catch(Exception e)
    {
        Log.e("Exception: ",e+" in setTheRuleContactListMaker() of ShowTheContacts1.java");
    }
}

//Runnable to load the items 
Runnable loadMoreListItems = new Runnable() {           
    @Override
    public void run() {
        //Set flag so we cant load new items 2 at the same time
        m_loadingMore = true;

        //Reset the array that holds the new items
        m_myListItems = new ArrayList<String>();

        if(SplashActivity.s_contactNameArrayListSplash.size() < m_itemsPerPage)
            m_itemsPerPage = SplashActivity.s_contactNameArrayListSplash.size();

        //Get 15 new listitems
        for (int i = 0; i < m_itemsPerPage; i++) {      

            //Fill the item with some bogus information
            m_myListItems.add(SplashActivity.s_contactNameArrayListSplash.get(i).toString());                           
        }

        //Done! now continue on the UI thread
        runOnUiThread(returnRes);

    }
};  


//Since we cant update our UI from a thread this Runnable takes care of that! 
Runnable returnRes = new Runnable() 
{
    @Override
    public void run() 
    {
        //Loop thru the new items and add them to the adapter
        if(m_myListItems != null && m_myListItems.size() > 0)
        {
            for(int i=0;i < m_myListItems.size();i++)
            {
                m_contactAdapterSetTheRule.add(m_myListItems.get(i));   
            }
        }

        //Tell to the adapter that changes have been made, this will cause the list to refresh
        m_contactAdapterSetTheRule.notifyDataSetChanged();

        //Done loading more.
        m_loadingMore = false;

    }
};

This is the error log:

12-11 15:12:28.535: E/AndroidRuntime(794): Uncaught handler: thread main exiting due to uncaught exception
12-11 15:12:28.545: E/AndroidRuntime(794): java.lang.NullPointerException
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.ListView.setupChild(ListView.java:1693)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.ListView.makeAndAddView(ListView.java:1671)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.ListView.fillDown(ListView.java:637)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.ListView.fillFromTop(ListView.java:694)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.ListView.layoutChildren(ListView.java:1521)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.AbsListView.onLayout(AbsListView.java:1113)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.view.View.layout(View.java:6830)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.LinearLayout.onLayout(LinearLayout.java:918)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.view.View.layout(View.java:6830)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.FrameLayout.onLayout(FrameLayout.java:333)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.view.View.layout(View.java:6830)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.LinearLayout.onLayout(LinearLayout.java:918)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.view.View.layout(View.java:6830)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.widget.FrameLayout.onLayout(FrameLayout.java:333)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.view.View.layout(View.java:6830)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.view.ViewRoot.performTraversals(ViewRoot.java:996)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1633)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.os.Handler.dispatchMessage(Handler.java:99)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.os.Looper.loop(Looper.java:123)
12-11 15:12:28.545: E/AndroidRuntime(794):  at android.app.ActivityThread.main(ActivityThread.java:4363)
12-11 15:12:28.545: E/AndroidRuntime(794):  at java.lang.reflect.Method.invokeNative(Native Method)
12-11 15:12:28.545: E/AndroidRuntime(794):  at java.lang.reflect.Method.invoke(Method.java:521)
12-11 15:12:28.545: E/AndroidRuntime(794):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
12-11 15:12:28.545: E/AndroidRuntime(794):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)

After these 2 lines,the debugger is moving to exception itself.

Thread thread =  new Thread(null, loadMoreListItems);
        thread.start();

I have searched a lot to get the work around,but am not getting any clue.Please help me.Thanks in advance.

Answer 1

Try using:

Thread thread =  new Thread(new Runnable() {

        @Override
        public void run() {
            //Set flag so we cant load new items 2 at the same time
    m_loadingMore = true;

    //Reset the array that holds the new items
    m_myListItems = new ArrayList<String>();

    if(SplashActivity.s_contactNameArrayListSplash.size() < m_itemsPerPage)
        m_itemsPerPage = SplashActivity.s_contactNameArrayListSplash.size();

    //Get 15 new listitems
    for (int i = 0; i < m_itemsPerPage; i++) {      

        //Fill the item with some bogus information
        m_myListItems.add(SplashActivity.s_contactNameArrayListSplash.get(i).toString());                           
    }

    //Done! now continue on the UI thread
    runOnUiThread(returnRes);
        }
    } );
        thread.start();

instead of:

Thread thread =  new Thread(null, loadMoreListItems);
        thread.start();