Design patterns lazy loading JAVA lazy loading
Example
Call from main()
// Simple lazy loader - not thread safe
HolderNaive holderNaive = new HolderNaive();
Heavy heavy = holderNaive.getHeavy();
Heavy.class
/**
*
* Heavy objects are expensive to create.
*
*/
public class Heavy {
private static final Logger LOGGER = LoggerFactory.getLogger(Heavy.class);
/**
* Constructor
*/
public Heavy() {
LOGGER.info("Creating Heavy ...");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
LOGGER.error("Exception caught.", e);
}
LOGGER.info("... Heavy created");
}
}
HolderNaive.class
/**
*
* Simple implementation of the lazy loading idiom. However, this is not thread safe.
*
*/
public class HolderNaive {
private static final Logger LOGGER = LoggerFactory.getLogger(HolderNaive.class);
private Heavy heavy;
/**
* Constructor
*/
public HolderNaive() {
LOGGER.info("HolderNaive created");
}
/**
* Get heavy object
*/
public Heavy getHeavy() {
if (heavy == null) {
heavy = new Heavy();
}
return heavy;
}
}
