处理Java异常导致未处理异常

Question

public List<OpBase> getHistory(ESRequest historyRequest)
        throws IOException, ResourceNotFoundException, URISyntaxException {
    String url = baseUrl + opIndex + "/_search";
    String resp = makeESQuery(historyRequest, url);
    HistoryResponse historyResponse = objectMapper.readValue(resp, HistoryResponse.class);
    List<OpBase> returnMsgList = new ArrayList<>();
    historyResponse.tasks.tasks.forEach(editTaskMsgResponse -> {
            Map<String, Object> msgObject = editTaskMsgResponse.source.msg;
            String taskType = (String) msgObject.get("task_type");
            EditTaskType editTaskType = EditTaskType.valueOf(taskType);
            switch(editTaskType) {
                case MIGRATE_PLACE: returnMsgList.add(objectMapper.readValue(
                        objectMapper.writeValueAsString(msgObject), MatchingTaskOperatorMetricsMsg.class));
                case CURATE_PLACE:
                case QC_PLACE: returnMsgList.add(objectMapper.readValue(objectMapper.writeValueAsString(msgObject),
                        MatchingTaskOperatorMetricsMsg.class));
            }
        });
    return returnMsgList;
}

我得到一个未处理的IOException异常错误，行如objectMapper.readValue(objectMapper.writeValueAsString(msgObject), MatchingTaskOperatorMetricsMsg.class));

但是我明确地说这个方法会抛出这个异常吗？

Answer 1

此警告可能显示的是包装在switch-case语句中的行。外面的那个会很好的。

原因是因为该代码位于lambda表达式中。在流和lambda表达式中，未处理的异常不是这样处理的。

您必须将在lambda表达式中编写的代码包装为try-catch。

historyResponse.tasks.tasks.forEach(editTaskMsgResponse -> {
            Map<String, Object> msgObject = editTaskMsgResponse.source.msg;
            String taskType = (String) msgObject.get("task_type");
            EditTaskType editTaskType = EditTaskType.valueOf(taskType);
            switch(editTaskType) {
                case MIGRATE_PLACE: 
                    try {
                        returnMsgList.add(objectMapper.readValue(objectMapper.writeValueAsString(msgObject), MatchingTaskOperatorMetricsMsg.class));
                    }
                    catch(IOException io) {}
                case CURATE_PLACE:
                case QC_PLACE: 
                    try {
                        returnMsgList.add(objectMapper.readValue(objectMapper.writeValueAsString(msgObject), MatchingTaskOperatorMetricsMsg.class));
                    }
                    catch(IOException io) {}
            }
        });

另请参阅：

1. Java 8 method reference unhandled exception
2. Java 8: How do I work with exception throwing methods in streams?