1. 遍历key和value - keySet
for(String key : map.keySet()){
Sysout.out.println(key + ": " + map.get(key) )
}
2. 遍历value - values
for (Integer value:map.values()){
System.out.println( "value :" + value );
}
3. 遍历key和value - entrySet
for (Map.Entry<String,Integer>entry :map.entrySet()){
System.out.println(entry.getKey()+ ": " +entry.getValue());
}
4. 遍历key和value - Iterator
for(Iterator<Map.Entry<String,Integer>> it=map.entrySet().iterator(); it.hasNext();){
Map.Entry<String, Integer> entry = it.next();
System.out.println( entry.getKey() + ": " + entry.getValue() );
}