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import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;
public class Main {
public static void main(String[] argv) throws Exception {
Map<String, Integer> map = new HashMap<String, Integer>();
map = new TreeMap();
map.put("a", new Integer(1));
map.put("b", new Integer(2));
map.put("c", new Integer(3));
int size = map.size(); // 2
Object oldValue = map.put("a", new Integer(9)); // 1
oldValue = map.remove("c"); // 3
Iterator it = map.keySet().iterator();
while (it.hasNext()) {
Object key = it.next();
}
it = map.values().iterator();
while (it.hasNext()) {
Object value = it.next();
}
}
}
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