David Vedvick


lazy-j: Lazy Java initialization library

Coming from the C# world, while working on audiocanoe I've often had the overwhelming desire to use something similar to the Lazy class that is in the Standard libs for .Net. Using it, you can easily initialize any object lazily without needing to implement your own double-check locked lazy initialization code.

So in a hasty moment, I wrote a library called lazy-j which supposedly guarantees your object will lazily be created the first time it is requested, using the supplied initialization function. It should also be thread-safe. It is also EXCEEDINGLY simple, here's the source:

package com.vedsoft.lazyj;

 * Created by david on 11/28/15.
public abstract class Lazy<T> {

    private T object;

    public boolean isInitialized() {
        return object != null;

    public T getObject() {
        return isInitialized() ? object : getValueSynchronized();

    private synchronized T getValueSynchronized() {
        if (!isInitialized())
            object = initialize();

        return object;

    protected abstract T initialize();

There's some nice things here; it uses Java's built in synchronized methods to do a double-checked lock for object initialization. It doesn't have all the niceties of Microsoft's library (such as different degrees of thread-safety), but it gets the job done nicely while being simple enough to understand at a glance.

Usage is also fairly simple. To instantiate a new object do something like below:

class MyClass {

    public static Lazy<MyCrazySingletonConfig> myCrazySingletonConfig = new Lazy<MyCrazySingletonConfig>() {
        protected MyCrazySingletonConfig initialize() {
            final MyCrazySingletonConfig newConfig = .....

            return newConfig;

class SomeOtherClassThatNeedsConfig {

    public void doingThingsWithConfig() {
        final String property = MyClass.myCrazySingletonConfig.getObject().getMyCrazyProperty();

You can view the source here!

Note posted on Tuesday, January 5, 2016 11:04 PM CST - link