Example usage for java.util WeakHashMap WeakHashMap

Introduction

In this page you can find the example usage for java.util WeakHashMap WeakHashMap.

Prototype

public WeakHashMap()

Source Link

Document

Constructs a new, empty WeakHashMap with the default initial capacity (16) and load factor (0.75).

Usage

From source file:org.openmrs.module.ModuleFactory.java

/**
 * Return all current classloaders keyed on module object
 * //www  . ja  v  a2  s  .com
 * @return Map&lt;Module, ModuleClassLoader&gt;
 */
public static Map<Module, ModuleClassLoader> getModuleClassLoaderMap() {
    if (moduleClassLoaders == null) {
        moduleClassLoaders = new WeakHashMap<Module, ModuleClassLoader>();
    }

    return moduleClassLoaders;
}

From source file:org.openmrs.module.ModuleFactory.java

/**
 * Return the current extension map keyed on extension point id
 * //from   w ww  .  j av  a  2 s  . c o  m
 * @return Map&lt;String, List&lt;Extension&gt;&gt;
 */
public static Map<String, List<Extension>> getExtensionMap() {
    if (extensionMap == null) {
        extensionMap = new WeakHashMap<String, List<Extension>>();
    }

    return extensionMap;
}

From source file:com.buaa.cfs.conf.Configuration.java

/**
 * Load a class by name, returning null rather than throwing an exception if it couldn't be loaded. This is to avoid
 * the overhead of creating an exception.
 *
 * @param name the class name/* ww  w  .  jav  a  2 s  .com*/
 *
 * @return the class object, or null if it could not be found.
 */
public Class<?> getClassByNameOrNull(String name) {
    Map<String, WeakReference<Class<?>>> map;

    synchronized (CACHE_CLASSES) {
        map = CACHE_CLASSES.get(classLoader);
        if (map == null) {
            map = Collections.synchronizedMap(new WeakHashMap<String, WeakReference<Class<?>>>());
            CACHE_CLASSES.put(classLoader, map);
        }
    }

    Class<?> clazz = null;
    WeakReference<Class<?>> ref = map.get(name);
    if (ref != null) {
        clazz = ref.get();
    }

    if (clazz == null) {
        try {
            clazz = Class.forName(name, true, classLoader);
        } catch (ClassNotFoundException e) {
            // Leave a marker that the class isn't found
            map.put(name, new WeakReference<Class<?>>(NEGATIVE_CACHE_SENTINEL));
            return null;
        }
        // two putters can race here, but they'll put the same class
        map.put(name, new WeakReference<Class<?>>(clazz));
        return clazz;
    } else if (clazz == NEGATIVE_CACHE_SENTINEL) {
        return null; // not found
    } else {
        // cache hit
        return clazz;
    }
}