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Set<String> set = new HashSet<String>();
set.add("aaa");
Iterator<String> its = set.iterator();
while(its.hasNext())
{
System.out.println(its.next());
}
Map<String,Object> map = new HashMap<String, Object>();
map.put("aaa", new Object());
Iterator<String> itm = map.keySet().iterator();
while(itm.hasNext())
{
System.out.println(itm.next());
}
import java.util.HashMap;
import java.util.Map;
public class NewCal {
public static void main(String[] args) {
Map<String,String> map = new HashMap<String,String>();
map.put("123","123");
map.put("123","124");
System.out.println(map.size());
}
}