一般情况下,要输出Map中的key 和 value 是先得到key的集合,然后再迭代(循环)由每个key得到每个value
而Entry可以一次性获得这两个值
Set set = map.keySet(); //keySet()
for(Iterator iter = set.iterator();iter.hasNext();)
{
String key = (String)iter.next(); //先获得键key
Integer value = (Integer)map.get(key); //再由键获得value
System.out.println(key + "=" + value);
}
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Set set = map.entrySet(); //entrySet()
for(Iterator iter = set.iterator();iter.hasNext();)
{
Map.Entry entry = (Map.Entry)iter.next();
String key = (String)entry.getKey(); //一次性获得键和值 key和value
String value = (String)entry.getValue();
System.out.println(key + ": " + value);
}