de.thksystems.util.lang.Deferred Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of cumin Show documentation

Commons for lang, crypto, xml, dom, text, csv, reflection, annotations, parsing, ...

There is a newer version: 4.3.3

/*
 * tksCommons
 *
 * Author  : Thomas Kuhlmann (ThK-Systems, http://www.thk-systems.de)
 * License : LGPL (https://www.gnu.org/licenses/lgpl.html)
 */
package de.thksystems.util.lang;

import java.util.Objects;
import java.util.function.Supplier;

/**
 * Lazy initialization using a {@link Supplier} (thread-safe).
 *
 * @see "Inspired by http://www.nosid.org/java8-threadsafe-lazy-initialization.html"
 */
public final class Deferred {
    private volatile boolean initialized = false;
    private final Supplier resultSupplier;
    private T result = null;

    public Deferred(Supplier resultSupplier) {
        this.resultSupplier = Objects.requireNonNull(resultSupplier);
    }

    public T get() {
        if (!initialized) {
            synchronized (this) {
                if (!initialized) { // Double safety
                    result = resultSupplier.get();
                    initialized = true;
                }
            }
        }
        return result;
    }

    public boolean isInitialized() {
        return initialized;
    }

    public void invalidate() {
        initialized = false;
    }
}