java常用小技巧！

1.判断集合是否为空CollectionUtils.isEmpty(list) 2.遍历map集合list是个集合类

List<Map<String, String>> list = new ArrayList<Map<String, String>>(); Iterator<Entry<String,String>> iterator = JsonUtils.toObject(substring.trim(), Map.class).entrySet().iterator(); while(iterator.hasNext()){ Entry<String, String> entry = iterator.next(); Map<String, String> map = new HashMap<String, String>(); map.put("value",entry.getValue()); map.put("key",entry.getKey()); list.add(map); }

3.去掉属性下划线改为驼峰式

public static String getPropertyName(String propertyName) { propertyName = propertyName.toLowerCase(); String[] name = propertyName.split("_"); propertyName = name[0]; for (int i = 1; i < name.length; i++) { propertyName = propertyName + name[i].substring(0,1).toUpperCase() + name[i].substring(1); } return propertyName; }

4.json，object互转换类用到的包com.fasterxml.jackson.databind.ObjectMapper

private static ObjectMapper mapper = new ObjectMapper(); /** * toJson(把对象转换成json)<br/> */ public static String toJson(Object value) { try { return mapper.writeValueAsString(value); } catch (Exception e) { log.error("转换json失败", e); throw new RuntimeException("json转换异常", e); } } /** * toObject(把json转换成对象)<br/> */ public static <T> T toObject(String json, Class<T> clazz) { try { return mapper.readValue(json, clazz); } catch (Exception e) { log.error("json转换对象失败", e); throw new RuntimeException("json转换对象异常", e); } }