HashMap - getting First Key value

Question

You can try this:

 Map<String,String> map = new HashMap<>();
 Map.Entry<String,String> entry = map.entrySet().iterator().next();
 String key = entry.getKey();
 String value = entry.getValue();

Keep in mind, HashMap does not guarantee the insertion order. Use a LinkedHashMap to keep the order intact.

Eg:

 Map<String,String> map = new LinkedHashMap<>();
 map.put("Active","33");
 map.put("Renewals Completed","3");
 map.put("Application","15");
 Map.Entry<String,String> entry = map.entrySet().iterator().next();
 String key= entry.getKey();
 String value=entry.getValue();
 System.out.println(key);
 System.out.println(value);

Output:

 Active
 33

Update: Getting first key in Java 8 or higher versions.

Optional<String> firstKey = map.keySet().stream().findFirst();
if (firstKey.isPresent()) {
    String key = firstKey.get();
}

To get the "first" value:

map.values().toArray()[0]

To get the value of the "first" key:

map.get(map.keySet().toArray()[0])

Note: Above code tested and works.

I say "first" because HashMap entries are not ordered.

However, a LinkedHashMap iterates its entries in the same order as they were inserted - you could use that for your map implementation if insertion order is important.

Java 8 way of doing,

String firstKey = map.keySet().stream().findFirst().get();

You may also try the following in order to get the entire first entry,

Map.Entry<String, String> entry = map.entrySet().stream().findFirst().get();
String key = entry.getKey();
String value = entry.getValue();

The following shows how you may get the key of the first entry,

String key = map.entrySet().stream().map(Map.Entry::getKey).findFirst().get();
// or better
String key = map.keySet().stream().findFirst().get();

The following shows how you may get the value of the first entry,

String value = map.entrySet().stream().map(Map.Entry::getValue).findFirst().get();
// or better
String value = map.values().stream().findFirst().get();

Moreover, in case wish to get the second (same for third etc) item of a map and you have validated that this map contains at least 2 entries, you may use the following.

Map.Entry<String, String> entry = map.entrySet().stream().skip(1).findFirst().get();
String key = map.keySet().stream().skip(1).findFirst().get();
String value = map.values().stream().skip(1).findFirst().get();