title: How to change image button on list view when on long click
body: <p>For example when i press longclick on one item on listview , its actual button will turn to delete button. I try like <code>next_sign.setBackgroundResource(R.drawable.delete);</code> but, it force close.</p>
  
  <pre><code>lv.setOnItemLongClickListener(new OnItemLongClickListener() {
  
              @Override
              public boolean onItemLongClick(AdapterView&lt;?&gt; parent, View view,
                      int position, long id) {
                  //next_sign.setBackgroundResource(R.drawable.delete);
                  return true;
              }
          });
  </code></pre>
  
  <pre>
  12-28 13:44:34.251: E/AndroidRuntime(9108): FATAL EXCEPTION: main
  12-28 13:44:34.251: E/AndroidRuntime(9108): java.lang.NullPointerException
  12-28 13:44:34.251: E/AndroidRuntime(9108):     at com.mycos.cycleborg.PreviousActivity$3.onItemLongClick(MenuListActivity.java:129)
  </pre>