Map做put时报空指针异常

场景

Map<String, String> lines = findA(find.getA(wA.getW((String) order.get("A"))));
     if (null==lines || lines.isEmpty()){
         log.info("过期了");
         lines.put("A",null);
         lines.put("B",null);
         lines.put("C",null);
         lines.put("D",null);
         lines.put("E",null);
     }

报错

java.lang.NullPointerException: null

更改

Map<String, String> lines = findA(find.getA(wA.getW((String) order.get("A"))));
     if (null==lines || lines.isEmpty()){
         //初始化
         lines = new HashMap<>();
         log.info("过期了");
         lines.put("A",null);
         lines.put("B",null);
         lines.put("C",null);
         lines.put("D",null);
         lines.put("E",null);
     }

原因：lines未初始化，sql查询出为空。