Find out how to discover the primary key or worth type HashMap in Java
The best solution to get the primary key or first worth from a HashMap in Java is to use the entrySet() methodology to get a set of key-value pairs, after which use the iterator() methodology to get an iterator over the set. Lastly, you need to use the subsequent() methodology to get the primary entry within the Map.
Here is a code instance which reveal that:
Map<String, Integer> map = new HashMap<>();
map.put("A", 1);
map.put("B", 2);
map.put("C", 3);
String firstKey = map.keySet().iterator().subsequent();
System.out.println("First key: " + firstKey);
When you’ll run this code snippet you’re going to get following output:
Output:
Equally, To search out the primary worth from a Map, you need to use the values() methodology to get a set of values, after which use the iterator() methodology to get an iterator over the gathering. Lastly, you need to use the subsequent() methodology to get the primary worth within the Map.
Here is an instance:
Map<String, Integer> map = new HashMap<>();
map.put("A", 1);
map.put("B", 2);
map.put("C", 3);
Integer firstValue = map.values().iterator().subsequent();
System.out.println("First worth: " + firstValue);
When you’ll run this program you’re going to get following output:
That is all about how one can get the primary key, worth and entry from a HashMap in Java. As I mentioned, it relies upon upon kind of Map you’re utilizing, in case you are utilizing a sorted Map like TreeMap, you may get the primary key and entry simply by utilizing firstKey() and firstEntry() methodology after which you may get the worth from the Entry object.
For unsorted maps, we will use the iterator() methodology of the map to get the primary entry, key, or worth.
As well as, we will additionally use the entrySet() methodology to get the set of entries within the map and use the stream() methodology of Java 8 to filter the primary entry primarily based on the situations specified.
By selecting the suitable methodology primarily based on the map’s traits and necessities, builders can simply retrieve the primary entry, key, or worth from a map in Java.
Different Java HashMap tutorials chances are you’ll wish to discover:
- How does get() methodology of HashMap work in Java? (reply)
- Find out how to replace worth for a key in HashMap (replace instance)
- Distinction between ArrayList and HashMap? (distinction)
- Find out how to use computeIfAbsent() in HashMap? (compute instance)
- 3 methods to loop over a Map in Java? (instance)
- 40 HashMap interview questions with solutions (HashMap questions)
- HashSet vs HashMap in Java? (reply)
- How HashSet internally works in Java? (reply)
- Find out how to merge two HashMap in Java? (merge instance)
- HashMap vs LinkedHashMap in Java? (reply)
- ArrayList vs HashMap in Java? (reply)
- Distinction between ConcurrentHashMap and HashMap in Java? (reply)
- Find out how to type the HashMap on keys and values in Java? (answer)
- How ConcurrentHashMap internally works in Java? (reply)
- HashMap vs ConcurrentHashMap in Java? (reply)
- The easiest way to iterate over HashMap in Java? (reply)
- Distinction between HashMap vs Hashtable in Java? (reply)
- Find out how to convert Map to Record in Java? (answer)
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