public class MapTest {
public static void main(String args[]){
Map<String, Integer> map = new HashMap<>();
List list =new ArrayList<>();
System.out.println(list.size());
map.put("1", 1);
map.put("2", 2);
map.put("3", 3);
map.put("4", 4);
//采用keyset()迭代器
Iterator iterator =map.keySet().iterator();
while (iterator.hasNext()) {
Object key= iterator.next();
System.out.println("key: "+key + "值为:"+map.get(key));
}
Object key;
Object value;
//采用entryset()迭代
Iterator iterator2=map.entrySet().iterator();
while (iterator2.hasNext()) {
Map.Entry entry = (Map.Entry) iterator2.next();
key = entry.getKey();
value=entry.getValue();
System.out.println("key:"+key +"value:"+value);
}
System.out.println();
//采用foreach
for (String key1 : map.keySet()) {
System.out.println("key1:"+key1 + "value :"+map.get(key1));
}
}
}