How Does the get() Function Work for Java HashMaps?

What is the get() function in Java HashMaps and how is it used?

HashMap<String, Integer> map = new HashMap<>();
map.put("A", 1);
map.put("B", 2);
Integer value = map.get("A"); // Returns 1

The get() function in Java HashMaps is a key method that retrieves the value associated with a specific key. If the key is found, it returns the corresponding value; otherwise, it returns null.

HashMap<String, String> map = new HashMap<>();
map.put("Hello", "World");
String result = map.get("Hello"); // result will be "World"

if (map.containsKey("Hello")) {
    // Safe to retrieve value
    String value = map.get("Hello");
} else {
    // Handle missing key
}  
// Outputs the value associated with "Hello".

Causes

• The key does not exist in the HashMap.
• The HashMap is empty.

Solutions

• Verify that the key exists in the HashMap before calling get().
• Use containsKey() method to check for key presence.
• Ensure that the HashMap is properly initialized and populated.

Mistake: Attempting to access a key that does not exist in the HashMap.

Solution: Use the containsKey() method to check if the key is present before accessing it.

Mistake: Forgetting to initialize the HashMap before adding entries.

Solution: Make sure to create an instance of HashMap before using put() or get() methods.