Possible Duplicate:
Java: How to convert List to Map
I have arrayList
ArrayList<Product> productList = new ArrayList<Product>(); productList = getProducts(); //Fetch the result from db I want to convert to ArrayList to HashMap Like this
HashMap<String, Product> s= new HashMap<String,Product>(); Please help me how to convert to HashMap.
The general methodology would be to iterate through the ArrayList, and insert the values into the HashMap. An example is as follows:
HashMap<String, Product> productMap = new HashMap<String, Product>(); for (Product product : productList) { productMap.put(product.getProductCode(), product); } 
Using a supposed name property as the map key:
for (Product p: productList) { s.put(p.getName(), p); } [edited]
using your comment about productCode (and assuming product code is a String) as reference...
for(Product p : productList){ s.put(p.getProductCode() , p); } 
Producthave a unique property(ies)?Map<String, Product> urMap = yourList.stream().collect(Collectors.toMap(Product::getField1, Function.identity()));