Android listView 设置分割线问题

代码如下：

ListView lv = (ListView) findViewById(R.id.list2);
String [] str = {"唐三藏","孙悟空","八戒","沙僧","白马"};
ArrayAdapter<String> adapter = new ArrayAdapter<String>
(this, android.R.layout.simple_list_item_1, str);

//设置分割线
lv.setDivider(new ColorDrawable(Color.RED));
lv.setDividerHeight(2);

lv.setAdapter(adapter);

效果图：