Package com.github.trelawnm.weathersdk

Class WeatherCache

java.lang.Object
com.github.trelawnm.weathersdk.WeatherCache
public class WeatherCache extends Object
Thread-safe LRU (Least Recently Used) cache for weather data with TTL support.

This cache maintains weather data for up to maxSize cities, automatically evicting the least recently used entries when capacity is reached. Each cached entry has a time-to-live (TTL) after which it is considered stale and requires refresh from the API.

Features:

  • Fixed size with LRU eviction policy
  • TTL-based data freshness checking
  • O(1) time complexity for get and put operations
  • Thread-safe for concurrent access

Usage Example: 

 
 WeatherCache cache = new WeatherCache(10, Duration.ofMinutes(10));
 
 // Store weather data
 cache.put("London", weatherResponse);
 
 // Retrieve weather data (updates access order)
 WeatherResponse data = cache.get("London");
Version:
1.0
Author:
trelawnm
See Also:

  • Constructor Details

    • WeatherCache

      public WeatherCache(int maxSize, Duration ttl)
      Constructs a new weather cache with specified capacity and TTL.
      Parameters:
      maxSize - the maximum number of cities to cache (must be positive)
      ttl - the time-to-live duration for cached entries (cannot be null)
      Throws:
      IllegalArgumentException - if maxSize is not positive or ttl is null

  • Method Details

    • get

      public WeatherResponse get(String city)
      Retrieves weather data for the specified city.

      If the data exists and is not stale, it updates the access order and returns the weather data. If the data is stale, it is removed from the cache and null is returned.

      Parameters:
      city - the name of the city to look up
      Returns:
      the cached weather data, or null if not found or stale

    • put

      public void put(String city, WeatherResponse weatherData)
      Stores weather data for the specified city in the cache.

      If the cache has reached maximum capacity, the least recently used city is automatically evicted. The new entry is added with current timestamps for creation time.

      Parameters:
      city - the name of the city to cache
      weatherData - the weather data to store
      Throws:
      IllegalArgumentException - if city is null or weatherData is null

    • size

      public int size()
      Returns the current number of cities in the cache.
      Returns:
      the number of cached cities

    • getAllCities

      public Set<String> getAllCities()
      Returns all cities currently in cache
      Returns:
      set of city names

    • clear

      public void clear()
      Removes all entries from the cache.