CODEWITHSUNDEEP
androidoptimizationlistviewio
user685275
user685275

Reputation: 2157

trying to optimize listview and failed

I am trying to adopt Romain Guy's recommendation from google IO last year of a ViewHolder for a list to optimize list view for the example from: http://www.softwarepassion.com/android-series-custom-listview-items-and-adapters/ (thanks to admin) but whenever I try to flip through the list or even make it move a little bit, the application crashes, what is going on? any help would be appreciated :) here is what I did >

private class OrderAdapter extends ArrayAdapter<Order> {
    private ArrayList<Order> items;
    LayoutInflater mInflater;

    public OrderAdapter(Context context, int textViewResourceId, ArrayList<Order> items) {
        super(context, textViewResourceId, items);
        mInflater = LayoutInflater.from(context);
        this.items = items;
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.row, parent, false);
            holder = new ViewHolder();
            holder.tt = (TextView) convertView.findViewById(R.id.toptext);
            holder.bt = (TextView) convertView.findViewById(R.id.bottomtext);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }
        Order o = items.get(position);
        if (o != null) {
            if (holder.tt != null) {
                holder.tt.setText("Name: " + o.getOrderName());
            }
            if (holder.bt != null) {
                holder.bt.setText("Status: " + o.getOrderStatus());
            }
        }
        return convertView;
    }
}

This is the error message I got, sorry I don't know how to format it >

FATAL EXCEPTION: main java.lang.NullPointerException at com.softberries.lve.SoftwarePassionView$OrderAdapter.getView(SoftwarePassionView.java:98) at android.widget.AbsListView.obtainView(AbsListView.java:1294) at android.widget.ListView.makeAndAddView(ListView.java:1727) at android.widget.ListView.fillDown(ListView.java:652) at android.widget.ListView.fillGap(ListView.java:623) at android.widget.AbsListView.trackMotionScroll(AbsListView.java:2944) at android.widget.AbsListView.onTouchEvent(AbsListView.java:2065) at android.widget.ListView.onTouchEvent(ListView.java:3315) at android.view.View.dispatchTouchEvent(View.java:3766) at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:897) at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936) at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936) at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936) at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936) at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1671) at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107) at android.app.Activity.dispatchTouchEvent(Activity.java:2086) at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1655) at android.view.ViewRoot.handleMessage(ViewRoot.java:1785) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:123) at android.app.ActivityThread.main(ActivityThread.java:4627) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:521) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) at dalvik.system.NativeStart.main(Native Method)

Upvotes: 0

Views: 938

Answers (2)

GrAnd
GrAnd

Reputation: 10211

I see holder = (ViewHolder) convertView.getTag();. But I do not see where you invoke setTag() for convertView in body of if (convertView == null) {...} .

So, I guess you forgot the line:

convertView.setTag(holder);

Upvotes: 1

Dinesh Sharma
Dinesh Sharma

Reputation: 11571

Most probably you are getting ArrayIndexOutOfBound Exception. Use getCount() method of array adapter to declare the size of the list.

Upvotes: 0

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