HashMap - getting First Key value

148

Below are the values contain in the HashMap

statusName {Active=33, Renewals Completed=3, Application=15}

Java code to getting the first Key (i.e Active)

Object myKey = statusName.keySet().toArray()[0];

How can we collect the first Key "Value" (i.e 33), I want to store both the "Key" and "Value" in separate variable.

This question is tagged with java hashmap

~ Asked on 2014-10-07 06:54:37

The Best Answer is


280

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

~ Answered on 2014-10-07 06:57:06


78

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.

~ Answered on 2014-10-07 06:59:34


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