title: Android, changing background of list in array adapter?
body: <p>In my application i have list which i inflate it with array adapter. every thing is OK and i have my result in the list. </p>
  
  <p>I like to change background color of list (even rows red for example and odd rows green).</p>
  
  <p>This is xml of my rows:</p>
  
  <pre><code>&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="vertical"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      &gt;
      &lt;RelativeLayout
          android:id="@+id/rllist"
          android:orientation="horizontal"
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:layout_marginTop="15dip"
          android:layout_marginBottom="15dip"
          &gt;
          &lt;TextView
              android:id="@+id/outstanding_contractdate"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:textColor="#ffffff"
              android:textSize="15sp" /&gt;
          &lt;TextView
              android:id="@+id/outstanding_contractno"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_toRightOf="@id/outstanding_contractdate"
              android:paddingLeft="20dip"
              android:textColor="#ffffff"
              android:textSize="15sp" /&gt;
          &lt;TextView
              android:id="@+id/outstanding_contractamount"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_alignParentRight="true"
              android:textSize="15sp" /&gt;
      &lt;/RelativeLayout&gt;   
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>I have written following codes:</p>
  
  <pre><code>static class ViewHolder {
      RelativeLayout rlList;
      TextView tvContDate;
      TextView tvContNo;
      TextView tvContAmount;
  }
  </code></pre>
  
  <p>and in Array Adapter I have this one:</p>
  
  <pre><code>public View getView(int position, View convertView, ViewGroup parent){
              ViewHolder holder;
              View row = convertView;
  
              if(row == null){
                  LayoutInflater inflater = getLayoutInflater();
                  row = inflater.inflate(R.layout.list_outstanding, parent, false);
                  //convertView = mInflater.inflate(R.layout.list_outstanding, parent, false);
  
                  holder = new ViewHolder();
                  holder.rlList = (RelativeLayout) convertView.findViewById(R.id.rllist);
                  holder.tvContDate = (TextView) row.findViewById(R.id.outstanding_contractdate);
                  holder.tvContNo = (TextView) row.findViewById(R.id.outstanding_contractno); 
                  holder.tvContAmount = (TextView) row.findViewById(R.id.outstanding_contractamount);
  
                  row.setTag(holder);
              } else {
                  holder = (ViewHolder) row.getTag(); 
              }
  
                  holder.tvContDate.setText(llData.get(position).split(",")[0].trim());
                  holder.tvContNo.setText(llData.get(position).split(",")[1].trim());
                  holder.tvContAmount.setText(llData.get(position).split(",")[2].trim());
  
                  if(position%2 != 0)
                      holder.rlList.setBackgroundColor(0x00FF00);
                  else
                      holder.rlList.setBackgroundColor(0XFF0000); 
  
              return(row);
          }
  </code></pre>
  
  <p>after running application when i reach to this code, an error occurs. according to LogCat it is "Null Pointer Exception" and points to this line in getView():</p>
  
  <pre><code>holder.rlList = (RelativeLayout) convertView.findViewById(R.id.rllist);
  </code></pre>
  
  <p>it seems everything is OK, but I don't know where my problem is?!!!</p>
  
  <p>===========</p>
  
  <h1>Update</h1>
  
  <p>I have changed above line to:</p>
  
  <pre><code>holder.rlList = (RelativeLayout) row.findViewById(R.id.rllist);
  </code></pre>
  
  <p>and now i have my result but background did not applied?!!!</p>