Question

In my application, I have a ListActivity and a custom layout for it. In the custom layout, I have an ImageView and a TextView.

I want to be able to change the ImageView resource based on some conditional code in my app. However, when I try to image.setImageResource(resource);, I get javaNullPointerException. I have tried placing the code snippet in different places, like after the adapter. Does anyone have any ideas? Thanks in advance.

Also, I did declare the image view before referring to it with ImageView image = (ImageView) findViewById(R.id.image);

EDIT:

In my activity:

    setListAdapter(new ArrayAdapter<String>(this, R.layout.list_item, R.id.label, DlistArray));

    // Here I want to change the image
  ImageView celebIcon = (ImageView) findViewById(R.id.icon);
  celebIcon.setImageResource(R.drawable.phil);

  ListView celebList = getListView();
  registerForContextMenu(getListView());
  celebList.setTextFilterEnabled(true);

In my layout:

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:cacheColorHint="#00000000"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >

<ImageView
    android:id="@+id/icon"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_marginLeft="10dp"
    android:padding="10dp"
    android:src="@drawable/alan" />

<TextView
    android:id="@+id/label"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:padding="10dp"
    android:layout_gravity="center_vertical"
    android:text="@+id/label"
    android:textColor="#ffffff"
    android:textSize="20dp" />
    </LinearLayout>

Answer 1

Use a customized adapter:

setListAdapter(new ArrayAdapter<String>(getApplicationContext(), R.layout.list_item, R.id.label, yourItems){
                @Override
                public View getView(int position, View convertView, ViewGroup parent) {
                    if( convertView == null ){
                        LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                        convertView = inflater.inflate(R.layout.list_item, null);
                    }

                    ImageView image = (ImageView) findViewById(R.id.icon);
                    image.setImageResource(R.drawable.phil);
                    return convertView;
                }
            });

(You can also just create your own class extending arrayadapter if you want to reuse it)

To set the text view, just add the code for that in the getView() method, just like the image-setting-code.