Start activity from adapter don't work with SwipeListView library

Question

I'm using SwipeListView library and I'm getting error when trying to start an activity in my adapter.

public class ProductAdapter extends ArrayAdapter<Product> {

private Context context;

public ProductAdapter(Context context, int textViewResourceId, List<Product> objects) {
    super(context, textViewResourceId, objects);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    ViewHolder viewHolder;

    final Product product = getItem(position);

    if (convertView == null) {
        viewHolder = new ViewHolder();

        convertView = LayoutInflater.from(getContext()).inflate(R.layout.cproduct_list_item, null);

        viewHolder.nom = (TextView) convertView.findViewById(R.id.name);
        viewHolder.commerce = (TextView) convertView.findViewById(R.id.commerce);
        viewHolder.prix = (TextView) convertView.findViewById(R.id.price);
        viewHolder.bAction1 = (Button) convertView.findViewById(R.id.example_row_b_action_1);
        viewHolder.bAction2 = (Button) convertView.findViewById(R.id.example_row_b_action_2);
        viewHolder.bAction3 = (Button) convertView.findViewById(R.id.example_row_b_action_3);

        convertView.setTag(viewHolder);

    } 
    else {
        viewHolder = (ViewHolder) convertView.getTag();
    }

    viewHolder.nom.setText(product.getName());
    viewHolder.commerce.setText(product.getCommerce());
    viewHolder.prix.setText(String.format("%s F", product.getPrice()));

    viewHolder.bAction1.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(context, MainActivity.class);
            context.startActivity(intent);
        }
    });

    return convertView;
}

private class ViewHolder {
    TextView nom;
    TextView commerce;
    TextView prix;
    Button bAction1;
    Button bAction2;
    Button bAction3;
}
}

When I click on the button I get this error: "The application has stopped unexpectedly". But when I use a Toast, it works fine. I think there is something inconsistent with starting activity.

Logcat:

04-16 18:42:29.531: E/AndroidRuntime(29813): FATAL EXCEPTION: main 04-16 18:42:29.531: E/AndroidRuntime(29813): java.lang.NullPointerException 04-16 18:42:29.531: E/AndroidRuntime(29813): at com.tomsyweb.suna.ProductAdapter$2.onClick(ProductAdapter.java:71) 04-16 18:42:29.531: E/AndroidRuntime(29813): at android.view.View.performClick(View.java:2485) 04-16 18:42:29.531: E/AndroidRuntime(29813): at android.view.View$PerformClick.run(View.java:9080) 04-16 18:42:29.531: E/AndroidRuntime(29813): at android.os.Handler.handleCallback(Handler.java:587) 04-16 18:42:29.531: E/AndroidRuntime(29813): at android.os.Handler.dispatchMessage(Handler.java:92) 04-16 18:42:29.531: E/AndroidRuntime(29813): at android.os.Looper.loop(Looper.java:130) 04-16 18:42:29.531: E/AndroidRuntime(29813): at android.app.ActivityThread.main(ActivityThread.java:3687) 04-16 18:42:29.531: E/AndroidRuntime(29813): at java.lang.reflect.Method.invokeNative(Native Method) 04-16 18:42:29.531: E/AndroidRuntime(29813): at java.lang.reflect.Method.invoke(Method.java:507) 04-16 18:42:29.531: E/AndroidRuntime(29813): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 04-16 18:42:29.531: E/AndroidRuntime(29813): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 04-16 18:42:29.531: E/AndroidRuntime(29813): at dalvik.system.NativeStart.main(Native Method)

score 1 · Accepted Answer · answered Apr 16 '13 at 19:04

1

context is a field of ProductAdapter in your case and you don't initialize it with any value, so it's null. Use getContext() instead or initialize context field with this.context = context.

answered Apr 16 '13 at 19:04

Michael

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getContext() doesn't solve the problem. I get another log error: 04-16 19:20:32.226: E/AndroidRuntime(32041): android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want? 04-16 19:20:32.226: E/AndroidRuntime(32041): at android.app.ContextImpl.startActivity(ContextImpl.java:654) – tsil Apr 16 '13 at 19:24
1

Thanks for your help. Finally get a solution here (use myIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);) http://stackoverflow.com/questions/3918517/calling-startactivity-from-outside-of-an-activity-context – tsil Apr 16 '13 at 19:31
It's not a good idea really. If the context you pass to the `ProductAdapter` is an `Activity`, you'd better save it in a field and use to start another `Activity` without creating a new task. – Michael Apr 17 '13 at 05:51
Don't exactly understand what you say. Can you illustrate it with some piece of code? – tsil Apr 17 '13 at 22:40
Save the `context` you pass to the `ProductAdapter` in a field: `this.context = context;`. Then use this field to start an `Activity`, like you did in the question. – Michael Apr 18 '13 at 07:59
I tried it but it doesn't work: "Calling startActivity() from outside of an Activity context requires the FLAG_ACTIVITY_NEW_TASK flag" – tsil Apr 18 '13 at 17:28
What do you pass as a `context` to `ProductAdapter`? – Michael Apr 18 '13 at 17:35
Context context; public ProductAdapter(Context context, int textViewResourceId, List objects) { super(context, textViewResourceId, objects); this.context = context; } – tsil Apr 18 '13 at 18:34
No, I mean when you create a `ProductAdapter` with `new ProductAdapter(...)` what is the first argument there? – Michael Apr 19 '13 at 03:37
2

Oh, never use it! I think you call it from an `Activity` subclass, so just pass this activity to the constructor (`this` in your case). Then you can remove the `context` field from the `ProductAdapter` class and use `getContext()` without any limitations. – Michael Apr 19 '13 at 09:10

score 0 · Answer 2 · answered Dec 02 '16 at 01:03

You are receiving the Context in the constructor, so you can store into the variable context:

private Context context;

public ProductAdapter(Context context, int textViewResourceId, List<Product> objects) {
    super(context, textViewResourceId, objects);
    this.context = context; //*** Here!
}

And use it into your Adapter class, for example:

...
...
  viewHolder.bAction1.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(context, MainActivity.class);
            context.startActivity(intent);
        }
    });
...
...

Start activity from adapter don't work with SwipeListView library

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