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:Main.java

public static void main(String[] argv) throws Exception {
    Map weakMap = new WeakHashMap();
    Object keyObject = "";
    Object valueObject = "";
    weakMap.put(keyObject, valueObject);

    Iterator it = weakMap.keySet().iterator();
    while (it.hasNext()) {
        Object key = it.next();//from   w  w  w.  j a v a  2  s.com
    }
}

From source file:MainClass.java

public static void main(String args[]) {
    map = new WeakHashMap();
    map.put("A", "B");
    Runnable runner = new Runnable() {
        public void run() {
            while (map.containsKey("A")) {
                try {
                    Thread.sleep(1000);
                    System.gc();//from   www .j av  a 2s.  c o m
                } catch (InterruptedException ignored) {
                }
                System.out.println("Has A");
                System.gc();
            }
        }
    };
    Thread t = new Thread(runner);
    t.start();
    System.out.println("Main waiting");
    try {
        t.join();
    } catch (InterruptedException ignored) {
    }
    System.gc();
}

From source file:Main.java

public static void main(String[] args) {
    WeakHashMap<String, String> weakHashMapOne = new WeakHashMap<String, String>();
    WeakHashMap<String, String> weakHashMapTwo = new WeakHashMap<String, String>();

    System.out.println("Populating two Maps");

    weakHashMapOne.put("1", "first");
    weakHashMapOne.put("2", "two");
    weakHashMapOne.put("3", "from java2s.com");

    weakHashMapTwo.put("1", "1st");
    weakHashMapTwo.put("2", "2nd");
    weakHashMapTwo.put("3", "3rd");

    // checking Map
    System.out.println("Before - Map 1: " + weakHashMapOne);
    System.out.println("Before - Map 2: " + weakHashMapTwo);

    // putting map 2 into map1
    weakHashMapOne.putAll(weakHashMapTwo);

    System.out.println("After - Map 1: " + weakHashMapOne);
    System.out.println("After - Map 2: " + weakHashMapTwo);
}

From source file:Main.java

public static void main(String[] args) {
    WeakHashMap<String, String> weakHashMap = new WeakHashMap<String, String>();

    weakHashMap.put("1", "first");
    weakHashMap.put("2", "two");
    weakHashMap.put("3", "from java2s.com");

    // printing the contents of the Map
    System.out.println("Contents of the Map");
    System.out.println(weakHashMap);

    // populating the set
    Set set = weakHashMap.keySet();
    System.out.println("Contents of the set");
    System.out.println(set);//from   w  ww  . j a  v  a 2  s . com
}

From source file:Main.java

public static void main(String[] args) {
    WeakHashMap<String, String> weakHashMap = new WeakHashMap<String, String>();

    System.out.println("Putting values into the Map");
    weakHashMap.put("1", "first");
    weakHashMap.put("2", "two");
    weakHashMap.put("3", "from java2s.com");

    // checking the size of the Map
    System.out.println("Map values: " + weakHashMap);

    Collection col = weakHashMap.values();
    System.out.println("Collection values: " + col);
}

From source file:Main.java

public static void main(String[] args) {
    WeakHashMap<String, String> weakHashMap = new WeakHashMap<String, String>();

    weakHashMap.put("1", "first");
    weakHashMap.put("2", "two");
    weakHashMap.put("3", "from java2s.com");

    // printing the Map
    System.out.println("Map: " + weakHashMap);

    // returns a Set view of the Map
    Set set = weakHashMap.entrySet();

    // printing the set
    System.out.println("Set: " + set);

    // change Map value
    weakHashMap.put("3", "new value");

    // print Map and set
    System.out.println("Changed Map: " + weakHashMap);
    System.out.println("Changed Set: " + set);

}

From source file:Main.java

public static void main(String args[]) {

    Map<String, Boolean> map = new WeakHashMap<String, Boolean>();

    // create a set from map
    Set<String> set = Collections.newSetFromMap(map);

    // add values in set
    set.add("Java");
    set.add("C");
    set.add("C++");
    set.add("from java2s.com");

    // set and map values are
    System.out.println("Set is: " + set);
    System.out.println("Map is: " + map);
}

From source file:Main.java

public static void main(String[] argv) throws Exception {
    Object keyObject = "";
    Object valueObject = "";
    Map weakMap = new WeakHashMap();

    weakMap.put(keyObject, valueObject);
    WeakReference weakValue = new WeakReference(valueObject);

    weakMap.put(keyObject, weakValue);/*from ww  w.j a va  2  s  . com*/

    Iterator it = weakMap.keySet().iterator();
    while (it.hasNext()) {
        Object key = it.next();
        weakValue = (WeakReference) weakMap.get(key);
        if (weakValue == null) {
            System.out.println("Value has been garbage-collected");
        } else {
            System.out.println("Get value");
            valueObject = weakValue.get();
        }
    }
}

From source file:Main.java

public static void main(String[] argv) throws Exception {
    Object keyObject = "";
    Object valueObject = "";
    Map<Object, Object> weakMap = new WeakHashMap<Object, Object>();

    weakMap.put(keyObject, valueObject);
    WeakReference weakValue = new WeakReference<Object>(valueObject);

    weakMap.put(keyObject, weakValue);/*  ww  w  .  ja  v  a  2 s.c o  m*/

    Iterator it = weakMap.keySet().iterator();
    while (it.hasNext()) {
        Object key = it.next();
        weakValue = (WeakReference) weakMap.get(key);
        if (weakValue == null) {
            System.out.println("Value has been garbage-collected");
        } else {
            System.out.println("Get value");
            valueObject = weakValue.get();
        }
    }
}

From source file:Main.java

public static <K, V> WeakHashMap<K, V> createWeakHashMap() {
    return new WeakHashMap<K, V>();
}