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| 9. 30. 5. To enable automatically release of the value, the value must be wrapped in a WeakReference object |
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import java.lang.ref.WeakReference;
import java.util.Iterator;
import java.util.Map;
import java.util.WeakHashMap;
public class Main {
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);
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();
}
}
}
}
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