import java.util.Map;
import java.util.WeakHashMap;
public class MainClass {
private static Map map;
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();
} 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();
}
}