How to use LRU slow existence in the Java library
How to use LRU slow existence in the Java library
When it comes to cache, the most commonly used strategy is LRU (Least Recently Used, recently used at least) algorithm.In the Java library, we can use the LinkedhashMap class to achieve the LRU cache, which provides a hash table with a access order.
It is very simple to use the LINKEDHASHMAP class to achieve the LRU cache.We just need to set the AccessOrder parameter to True when creating the LinkedhashMap object to enable the access order.When accessing the cache, the accessed elements will be moved to the end of the queue, ensuring that the recently visited elements are always at the end of the queue.
The following is a sample code that uses lrudhashmap to achieve LRU cache:
import java.util.LinkedHashMap;
import java.util.Map;
public class LRUCache<K, V> extends LinkedHashMap<K, V> {
private final int maxSize;
public LRUCache(int maxSize) {
super(maxSize, 0.75f, true);
this.maxSize = maxSize;
}
@Override
protected boolean removeEldestEntry(Map.Entry eldest) {
return size() > maxSize;
}
public static void main(String[] args) {
// Create a LRU cache with a maximum capacity of 3
LRUCache<Integer, String> cache = new LRUCache<>(3);
// Add element to cache
cache.put(1, "A");
cache.put(2, "B");
cache.put(3, "C");
System.out.println(cache);
// Visit element 2, place it at the end
String value = cache.get(2);
System.out.println(cache);
// Add element D
cache.put(4, "D");
System.out.println(cache);
// Add element E, which will cause the oldest element 1
cache.put(5, "E");
System.out.println(cache);
}
}
Run the above example code, you can get the following output of LRU cache:
{1=A, 2=B, 3=C}
{1=A, 3=C, 2=B}
{3=C, 2=B, 4=D}
{2=B, 4=D, 5=E}
It can be seen from the output that the maximum capacity of the LRU cache is 3.After adding elements to cache, the oldest element is removed when the number of elements exceeds the maximum capacity.The access element will place it at the end of the queue.
By using the LinkedhashMap class in the Java library, we can easily achieve the LRU cache.This cache strategy is particularly useful when processing frequent access to data, which can improve the performance and response speed of the system.
