How to make ExpandableListView with JSON data in Android

In my app I want to make a ExpandableListView parsing JSON data. Here is my JSON data.

 [  
   {  
      "UserId":"raj",
      "PrvCusID":"10000000",
      "ItemName":"popcorn",
      "RPU":75.0000,
      "VAT":0.0000,
      "QTY":1,
      "CustomerName":"Rakib Hossain"
   },
   {  
      "UserId":"raj",
      "PrvCusID":"10000001",
      "ItemName":"chips",
      "RPU":50.0000,
      "VAT":0.0000,
      "QTY":1,
      "CustomerName":"Sehav"
   }
]

Here "CustomerName" will be group name and "ItemName", "RPU", "QTY" will be in child. For a customer there will be many items, and have to show total "RPU" for each customer. How can I do this. Thanks in advance.