集合分组Map
月似人伤 2017-11-08 03:35:49 List<LedgerInfo> result = new ArrayList<LedgerInfo>();
if (null == list || list.size() == 0)
{
return result;
}
Map<String, String> map = new HashMap<String, String>();
Map<String, List<LedgerInfo>> listMap = new LinkedHashMap<String, List<LedgerInfo>>();
List<LedgerInfo> modelList = null;
for (LedgerInfo ledgerInfo : list)
{
String accOperId = ledgerInfo.getAccOperId(); //accOperId
String dealerID = ledgerInfo.getDealerID(); //门店ID
String temp = accOperId + "_" + dealerID;
if (map.get(temp) == null)
{
modelList = new ArrayList<LedgerInfo>();
map.put(temp, temp);
}
else
{
modelList = (List<LedgerInfo>) listMap.get(temp);
}
modelList.add(ledgerInfo);
listMap.put(temp, modelList);
}
Map<String, String> map = new HashMap<String, String>();
map.put("1", "value1");
map.put("2", "value2");
map.put("3", "value3");
//第一种:普遍使用,二次取值
System.out.println("通过Map.keySet遍历key和value:");
for (String key : map.keySet()) {
System.out.println("key= "+ key + " and value= " + map.get(key));
}
//第二种
System.out.println("通过Map.entrySet使用iterator遍历key和value:");
Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<String, String> entry = it.next();
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
//第三种:推荐,尤其是容量大时
System.out.println("通过Map.entrySet遍历key和value");
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
//第四种
System.out.println("通过Map.values()遍历所有的value,但不能遍历key");
for (String v : map.values()) {
System.out.println("value= " + v);
}
}