Example tutorial of the LRU cache framework in the Java class library
Example tutorial of the LRU cache framework in the Java class library
Introduction:
LRU (Least Recently Used) cache is a common cache strategy. It removes the most recently used data from the cache to keep the data in the cache the most commonly used data.In the Java class library, we can use the ready -made LRU cache framework to achieve this strategy, which greatly simplifies the work of cache management.This article will introduce the use of the LRU cache framework in the Java library and provide the corresponding code example.
Preparation:
Before starting, we need to ensure that you have installed the Java Development Tool Pack (JDK) and have basic Java programming knowledge.
Step 1: Import the required class library
The Java class library provides a class called "Linkedhashmap", which has implemented the LRU cache strategy.We first need to import this class library:
import java.util.LinkedHashMap;
Step 2: Create the LRU cache instance
We can create an LRU cache instance by inheriting the LinkedhashMap class.In the process of inheritance, we need to rewrite the Removeldestentry method and set the cache size as needed.
Below is an example code, where we create a LRU cache instance with a maximum capacity of 10:
public class LRUCache<K, V> extends LinkedHashMap<K, V> {
private int capacity;
public LRUCache(int capacity) {
// The third parameter is set to TRUE, which means sorting in the order of access
super(capacity, 0.75f, true);
this.capacity = capacity;
}
@Override
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
return size() > capacity;
}
}
Step 3: Use the LRU cache instance
Once the LRU cache instance is created, we can use it directly for the cache operation.Here are some common cache operation examples:
1. Add data to the cache:
LRUCache<String, Integer> cache = new LRUCache<>(10);
cache.put("key1", 1);
cache.put("key2", 2);
2. Get the data from the cache:
int value1 = cache.get("key1");
3. Data in the cache:
for (Map.Entry<String, Integer> entry : cache.entrySet()) {
String key = entry.getKey();
int value = entry.getValue();
System.out.println(key + ": " + value);
}
4. Remove the data from the cache:
cache.remove("key1");
Summarize:
In the Java library, a ready -made LRU cache framework can be used to easily achieve cache strategies.By inheriting the LinkedhashMap class and rewriting the RemovelDestentry method, we can quickly create a customized LRU cache instance and can directly use the instance to cache operation.
I hope the tutorial of this article can help you learn and understand how to use the LRU cache framework in the Java class library.If you have any questions or doubts, you can ask questions in the comment area at any time.thanks for reading!
