Map<String, String> to TreeMap<Integer, String>

Question

I have a Map<String, String> object. I want to have it sorted by the keys, but the keys should be seen as integer. I just created an TreeMap<Integer, String>(myMapObject).

But this obviously does not work. How can I create a new TreeMap and change the keys from String to Integer?

Answer 1

You can use Collectors.toMap in Java 8:

Map<Integer, String> map1 = map.entrySet().stream().collect(Collectors.toMap(entry -> Integer.parseInt(entry.getKey()), Map.Entry::getValue, (a, b) -> b));

Or below traditional approach:

Map<Integer, String> map1 = new HashMap<>();

for(final Map.Entry<String, String> entry : map.entrySet()){
     map1.put(Integer.parseInt(entry.getKey()), entry.getValue());
}