Question

I have two methods:

private void openPrivate(String target) {
    currentKeyWindows = target;
    Log.i("better","openPrivate "+ target);
    if (windows.containsKey(currentKeyWindows)) {
    } else {
        tw = createTextView(currentKeyWindows);

        ActionBar.Tab newTab = getSupportActionBar().newTab();
        newTab.setText(currentKeyWindows);
        newTab.setTabListener(MainActivity.this);

        getSupportActionBar().addTab(newTab, true);
    }
}

private void jointochannel(String target) {
    currentKeyWindows = "#" + target;
    Log.i("better","jointochannel "+ target);
    if (windows.containsKey(currentKeyWindows)) {
    } else {
        tw = createTextView(currentKeyWindows);
        listofnicks.put(currentKeyWindows, new ArrayList<String>());
        nicklistadapter = new ArrayAdapter<String>(this, R.xml.mylistview, listofnicks.get(currentKeyWindows));
        nicklist.setAdapter(nicklistadapter);

                registerForContextMenu(nicklist);  


        ActionBar.Tab newTab = getSupportActionBar().newTab();
        newTab.setText(currentKeyWindows);
        newTab.setTabListener(MainActivity.this);

        getSupportActionBar().addTab(newTab, true);
        irc.addCommand(new Command(Command.JOIN_TO_CHANNEL, "JOIN " + currentKeyWindows));
    }
            channel = currentKeyWindows;
}

The second method works well. The first method (openPrivate) ends by null point exceptions at the line:

getSupportActionBar().addTab(newTab, true);

My AndroidManifest.xml:

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >

What to do? Why the same code works differently?
Regards, Denis.

LogCat:

11-04 17:06:57.241: E/AndroidRuntime(4696): FATAL EXCEPTION: main
11-04 17:06:57.241: E/AndroidRuntime(4696): java.lang.NullPointerException
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.widget.ArrayAdapter.getCount(ArrayAdapter.java:291)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.widget.ListView.setAdapter(ListView.java:454)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at ru.startandroid.develop.MainActivity.onTabSelected(MainActivity.java:427)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at com.actionbarsherlock.internal.app.ActionBarImpl.selectTab(ActionBarImpl.java:526)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at com.actionbarsherlock.internal.app.ActionBarImpl.addTab(ActionBarImpl.java:452)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at ru.startandroid.develop.MainActivity.openPrivate(MainActivity.java:382)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at ru.startandroid.develop.MainActivity.onContextItemSelected(MainActivity.java:100)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.app.Activity.onMenuItemSelected(Activity.java:2209)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at com.android.internal.policy.impl.PhoneWindow$ContextMenuCallback.onMenuItemSelected(PhoneWindow.java:2785)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:143)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:855)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at com.android.internal.view.menu.MenuDialogHelper.onClick(MenuDialogHelper.java:137)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:873)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.widget.AdapterView.performItemClick(AdapterView.java:284)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.widget.ListView.performItemClick(ListView.java:3513)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:1812)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.os.Handler.handleCallback(Handler.java:587)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.os.Handler.dispatchMessage(Handler.java:92)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.os.Looper.loop(Looper.java:130)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at android.app.ActivityThread.main(ActivityThread.java:3683)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at java.lang.reflect.Method.invokeNative(Native Method)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at java.lang.reflect.Method.invoke(Method.java:507)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-04 17:06:57.241: E/AndroidRuntime(4696):     at dalvik.system.NativeStart.main(Native Method)

onTabSelected(Tab tab, FragmentTransaction ft):

    public void onTabSelected(Tab tab, FragmentTransaction ft)
{
    currentKeyWindows = tab.getText().toString();

    mScrollView.removeAllViews();
    mScrollView.addView(this.windows.get(this.currentKeyWindows));
    scrollToBottom();


    nicklistadapter = new ArrayAdapter<String>(this, R.xml.mylistview, listofnicks.get(currentKeyWindows));
    nicklist.setAdapter(nicklistadapter);

    registerForContextMenu(nicklist);  
    channel=currentKeyWindows;

}

Answer 1

Judging from your LogCat it appears that the array you pass to your adapter is null:

nicklistadapter = new ArrayAdapter<String>(this, R.xml.mylistview, listofnicks.get(currentKeyWindows));

I would verify that listofnicks.get(currentKeyWindows) returns a valid result.