长按时如何更改列表视图上的图像按钮

Question

For example when i press longclick on one item on listview , its actual button will turn to delete button. I try like next_sign.setBackgroundResource(R.drawable.delete); but, it force close.

lv.setOnItemLongClickListener(new OnItemLongClickListener() {

            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View view,
                    int position, long id) {
                //next_sign.setBackgroundResource(R.drawable.delete);
                return true;
            }
        });

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)

Answer 1

you have to declare two buttons of your first item and delete button at same position in your layout make visibility of your original button to

android:visibility="visible" 

and make visibility of delete button to gone in layout using

android:visibility="gone" 

in programming

lv.setOnItemLongClickListener(new OnItemLongClickListener() {

            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View view,
                    int position, long id) {
              Original_Button.setVisibility(View.Gone);
               delete_Button.setVisibility(View.Visible); 
                return true;
            }
        });

Answer 2

public boolean onItemLongClick(AdapterView<?> arg0, View view, int arg2, long arg3) {
   Button mButton = (Button)view.findViewById(R.id.button);
   mButton.setVisibility(View.Visible); 
   return true;
}