CODEWITHSUNDEEP
androidlistviewarraylist
Learning Always
Learning Always

Reputation: 1561

Add List Item to another list

I have two list view. I want to add list item from One List view to another. when Item add to another list , item should remove from first list. this is my EventDetailActivity code.

public class EventDetailActivity extends AppCompatActivity {

    private ListView myListViewEventDetailList, myListViewAddEventDetailList;
    String[] eventItemList;
    Context context;
    ArrayList<String> addEventList = new ArrayList<String>();
    ArrayAdapter<String> arrayAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_event_detail);

        myListViewEventDetailList = (ListView) findViewById(R.id.listViewEventDetailList);
        myListViewAddEventDetailList = (ListView) findViewById(R.id.listViewAddEventDetailList);
        context = this;

        String[] eventItemList = {"EventItemList1","EventItemList2","EventItemList3","EventItemList4","EventItemList5"};
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,R.layout.event_detail_item,eventItemList);
        myListViewEventDetailList.setAdapter(adapter);

        myListViewEventDetailList.setItemsCanFocus(false);
        myListViewEventDetailList.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
        myListViewEventDetailList.setOnItemClickListener(new OnCheckBoxClick());

        arrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, addEventList);

    }

    private class OnCheckBoxClick implements android.widget.AdapterView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                addEventList.add(eventItemList[position]);
        }
    }
}

when I click to listItem to add items it will give error that Attempt to read from null array how can I do that?

thank you.

this is my error:

FATAL EXCEPTION: main Process: com.sabhagruh.ysgoperations, PID: 28001 java.lang.NullPointerException: Attempt to read from null array at com.sabhagruh.ysgoperations.EventDetailActivity$OnCheckBoxClick.onItemClick(EventDetailActivity.java:45) at android.widget.AdapterView.performItemClick(AdapterView.java:305) at android.widget.AbsListView.performItemClick(AbsListView.java:1146) at android.widget.AbsListView$PerformClick.run(AbsListView.java:3053) at android.widget.AbsListView$3.run(AbsListView.java:3860) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5343) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)

also I want to remove Event List which are checked I have done this code.. but not working.

 private class OnCheckBoxClick implements android.widget.AdapterView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {


            addEventList.add(eventItemList[position]);
            arrayAdapter.notifyDataSetChanged();
          /*  adapter.remove(adapter.getItem(position));
            myListViewEventDetailList.invalidateViews();
            adapter.notifyDataSetChanged();*/



        }
    }

Upvotes: 1

Views: 2054

Answers (2)

Anup Dasari
Anup Dasari

Reputation: 488

In onCreate change this line

 String[] eventItemList = {"EventItemList1","EventItemList2","EventItemList3","EventItemList4","EventItemList5"};

to 

  eventItemList = {"EventItemList1","EventItemList2","EventItemList3","EventItemList4","EventItemList5"};

because you are creating another local variable eventItemList in oncreate instead of using member variable

Also add

myListViewAddEventDetailList.setAdapter(arrayAdapter) after last line in onCreate

and

arrayAdapter.notifyDataSetChanged() after addEventList.add(eventItemList[position]); in onItemClick method

Upvotes: 2

Guillaume Barr&#233;
Guillaume Barr&#233;

Reputation: 4218

You are shadowing the eventItemList attribute

Replace 

String[] eventItemList = {"EventItemList1","EventItemList2","EventItemList3","EventItemList4","EventItemList5"}

By :

eventItemList = {"EventItemList1","EventItemList2","EventItemList3","EventItemList4","EventItemList5"}

Your actual code only declares a local variable within the onCreate method and has no effect on the initialization of the activity attribute.

Upvotes: 1

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