How to automatically refresh Cache using Google Guava?

Question

I am using Google Guava library for caching. For automatic cache refresh we can do as follows:

cache = CacheBuilder.newBuilder()               
                      


        

Answer 1

Here is some sample code to refresh a cache. Guava cache is easy to implement and also it is fast.

import java.util.concurrent.ExecutionException
import java.util.concurrent.TimeUnit;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

public class GuavaTest {
    private static GuavaTest INSTANCE = new GuavaTest();

    public static GuavaTest getInstance(){
        return INSTANCE;
    }   

    private LoadingCache cache;

    private GuavaTest() {
        cache = CacheBuilder.newBuilder()
                .refreshAfterWrite(2,TimeUnit.SECONDS)
                .build(new CacheLoader() {
                        @Override
                        public String load(String arg0) throws Exception {
                            return addCache(arg0);
                        }
                });
    }

    private String addCache(String arg0) {
        System.out.println("Adding Cache");
        return arg0.toUpperCase();
    }

    public String getEntry(String args) throws ExecutionException{
        System.out.println(cache.size());
        return cache.get(args);
    }

    public static void main(String[] args) {
        GuavaTest gt = GuavaTest.getInstance();
        try {
            System.out.println(gt.getEntry("java"));
            System.out.println(gt.getEntry("java"));
            Thread.sleep(2100);
            System.out.println(gt.getEntry("java"));
            System.out.println(gt.getEntry("java"));
        } catch (ExecutionException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

I referred this article guava cache example