Java HashMap: Elevate Your Coding Skills-Java HashMap Mastery

Example

map.put('John Doe', '555-1234'); String phoneNumber = map.get('John Doe');

Scenario

In an online store's backend, `put()` is used to associate user IDs with their shopping cart objects. When a user checks out, `get()` retrieves their cart for processing.

Example

map.remove('John Doe');

Scenario

In a subscription-based service, `remove()` is invoked to delete a user's account and associated details when they choose to unsubscribe.

Example

if (map.containsKey('John Doe')) {...}

Scenario

In a voting system, `containsKey()` checks if a voter has already voted, ensuring one vote per person, while `containsValue()` might verify that the vote cast is valid.

Example

if (map.isEmpty()) {...}

Scenario

In a task management application, `size()` helps display the number of outstanding tasks, while `isEmpty()` checks if all tasks have been completed.

Example

for (String key : map.keySet()) {...}

Scenario

In a multi-language application, `keySet()` is used to iterate over language codes to dynamically load language resources, whereas `values()` might iterate over translations.