Java – How to do an array of hashmaps

arrayshashmapjava

This is what I tried to do, but it gives me a warning:

HashMap<String, String>[] responseArray = new HashMap[games.size()];

Type safety: The expression of type HashMap[ ] needs unchecked conversion to conform to HashMap[ ]

What gives? It works. Just ignore it:

@SuppressWarnings("unchecked")

No, you cannot parameterize it. I'd however rather use a List<Map<K, V>> instead.

List<Map<String, String>> listOfMaps = new ArrayList<Map<String, String>>();

To learn more about collections and maps, have a look at this tutorial.

new ArrayList<>(Arrays.asList(array));

Modern browsers have Array#includes, which does exactly that and is widely supported by everyone except IE:

console.log(['joe', 'jane', 'mary'].includes('jane')); //true

You can also use Array#indexOf, which is less direct, but doesn't require polyfills for outdated browsers.

console.log(['joe', 'jane', 'mary'].indexOf('jane') >= 0); //true

Many frameworks also offer similar methods:

Notice that some frameworks implement this as a function, while others add the function to the array prototype.