How I can convert the hashmap to array?

Question

I want hashmap to array

I create the hashmap

Map<Integer,File> selectedFiles = new Hashmap<>();

and put it some Map data

And I convert this hashmap's values to array so

File[] files = (File[]) selectedFiles.values().toArray();

But errors occur;

java.lang.Object[] cannot be cast to java.io.File[]

I know that when I want the hashmap's values to array, use .values.toArray() but maybe it is not corret;

This way is wrong?

• castletheperson: Possible duplicate of The easiest way to transform collection to array?
• ephemient: Unless you have other reasons, Android advice is to use SparseArray<File> instead of Map<Integer, File>: less boxing, lower memory usage.
• faranjit: Possible duplicate of Java: how to convert HashMap<String, Object> to array

Answer 1

Map<Integer, File> selectedFiles = new HashMap<>();
 selectedFiles.put(1, null);
 File[] files = selectedFiles.values().toArray(
 new File[selectedFiles.size()]);
 System.out.println(files);// We will get the object [Ljava.io.File;@15db9742

arrays. toArray without parameters creates an object array because the type information of the list is lost at runtime.

• Polaris Nation: Thanks you save my time

Answer 2

Please use below Code to convert HashMap to Array ,You can change String to File in your case.

 //Creating a HashMap object
 HashMap<String, String> map = new HashMap<String, String>();
 //Getting Collection of values from HashMap
 Collection<String> values = map.values();
 //Creating an ArrayList of values
 ArrayList<String> listOfValues = new ArrayList<String>(values);
 // Convert ArrayList to Array
 String stringArray[]=listOfValues.toArray(new String[listOfValues.size()])

• castletheperson: You can skip the intermediate ArrayList. Also, why not just use File?
• Chetan Joshi: @4castle Yes, you are right and I just put sample code to do this that's why using String .