How to iterate over a hashmap in Java?

1 year ago
William Carter
1 minute

There are various ways to iterate through a HashMap in Java. Here are some common methods:

  1. Traverse using Iterator:
  2. // Create a new HashMap with String keys and Integer values
    HashMap map = new HashMap<>();
    // Add key-value pairs to the HashMap
    Iterator> iterator = map.entrySet().iterator();
    while (iterator.hasNext()) {
    Map.Entry entry = iterator.next();
    String key = entry.getKey();
    Integer value = entry.getValue();
    // Perform operations on the key-value pairs
    }
  3. Iterate using a for-each loop:
  4. A HashMap named ‘map’ is created with String keys and Integer values. Entries are added to the HashMap and then operated on.
  5. Iterate through the key set of HashMap.
  6. Create a new HashMap with String keys and Integer values. Then, add key-value pairs to the HashMap and perform operations on each pair.
  7. Iterate over the set of values in a HashMap.
  8. // Create a HashMap and add key-value pairs
    HashMap map = new HashMap<>();

    // Iterate over the values in the HashMap and perform operations on them

It is important to note that HashMap is unordered, so it cannot guarantee that the order of traversal will be the same as the order of insertion. If you need to traverse in the order of insertion, consider using a LinkedHashMap.

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