java - 如何将附加“\ n”添加到 StringBuilder 以获取下一行的值？

Question

我有一个编辑弹出窗口。在我的代码中，我使用的是 String Builder 。我用 append 表示 '.' . 我的消息以“。”结尾。即点。如何使用“\n”让我的消息出现在下一行？我试过 historyMessage.append("\n"),historyMessage.append("\n") 和 historyMessage.append("\r\n"); 但这对我不起作用。任何人都可以请查看我的代码并在我错的地方提供帮助。

private String historyMessage(HdiGdvHistory hdiGdvHistory, String messageType) {
        StringBuilder historyMessage = new StringBuilder();
        HdiGdv gdv = hdiGdvDAO.getById(hdiGdvHistory.getHdiGdvId());
        hdiGdvHistoryList = hdiGdvHistoryDAO.getByIds(gdv.getId());
        if("approved".equals(messageType)  || "rejected".equals(messageType)){
            historyMessage.append("User "+hdiGdvHistory.getUser().getFirstName() +" has "+messageType);
        }

        if(hdiGdvHistoryList==null || hdiGdvHistoryList.isEmpty()){     
            if(!gdv.getHouseNumber().equals(hdiGdvHistory.getHouseNumber())){
                historyMessage.append(getHistoryMessage(hdiGdvHistory, "House Number" ,gdv.getHouseNumber(),hdiGdvHistory.getHouseNumber()));
                historyMessage.append(". ");
            }
        }else{
            hdiGdvHistoryList = hdiGdvHistoryDAO.getByFilteredIds(gdv.getId());
            System.out.println("list "+hdiGdvHistoryList.size());

            hdiGdvHistoryList = hdiGdvHistoryDAO.getByIds(gdv.getId());
            for (HdiGdvHistory history : hdiGdvHistoryList) {
                if(!hdiGdvHistory.getHouseNumber().equals(history.getHouseNumber())){
                    historyMessage.append(getHistoryMessage(hdiGdvHistory, "House Number" ,history.getHouseNumber(),hdiGdvHistory.getHouseNumber()));
                    historyMessage.append(". ");
                    break;
                }
            }
        }


    if(hdiGdvHistoryList==null || hdiGdvHistoryList.isEmpty()){
        if(!gdv.getCity().equals(hdiGdvHistory.getCity())){
            historyMessage.append(getHistoryMessage(hdiGdvHistory, "City" ,gdv.getCity(),hdiGdvHistory.getCity()));
            historyMessage.append(". ");
        }
    }else{
        for (HdiGdvHistory history : hdiGdvHistoryList) {
            if(!hdiGdvHistory.getCity().equals(history.getCity())){
                historyMessage.append(getHistoryMessage(hdiGdvHistory, "City" ,history.getCity(),hdiGdvHistory.getCity()));
                historyMessage.append(". ");
                break;
            }
        }
    }

       hdiGdvHistoryList.clear();
    gdv=new HdiGdv();
    hdiGdvHistory = new HdiGdvHistory();
    return historyMessage.toString();

}

private String getHistoryMessage(HdiGdvHistory hdiGdvHistory, String values , String preFieldValue ,String fieldValues ) {
        return "User "+hdiGdvHistory.getUser().getFirstName() +" has updated  " +values+ "  "+preFieldValue +" to "+fieldValues;
}

Answer 1

这应该可以解决问题：

historyMessage.append('\n');