java - 如何在Java中格式化CSV的行和列

Question

我的最终目标是连续收集数据（大约700行），并将其发送到CSV以便以后查看。
目前，我的代码正在正确发送数据，但似乎在同一位置进行打印-覆盖最后的输出并在其位置打印最新的输出。我似乎找不到如何在每个新输出中增加行数/列数的方法。

我的代码：

String output = ("The difference b/w sent and received is: " + milliseconds + " milliseconds" );
try (PrintWriter writer = new PrintWriter(new File("/storage/self/primary/Download/test.xlsx"))) {
    StringBuilder sb = new StringBuilder();
    sb.append(sentTimestamp);
    sb.append('\n');
    sb.append(responseTimestamp);
    sb.append('\n');
    sb.append(output);
    sb.append('\n');
    writer.write(sb.toString());
} catch (FileNotFoundException e) {
    System.out.println(e.getMessage());
}

它显示为：



2019-11-21 07:47:59.18

2019-11-21 07:47:59.492

The difference b/w sent and received is: 312 milliseconds



很好，但是每发送和接收一次新邮件，我都希望它以新的三行打印。如何在CSV文件中指定行/列？

Answer 1

您可以按照以下步骤进行操作：

FileWriter fileWriter = new FileWriter("/storage/self/primary/Download/test.xlsx", true); //Set true for append mode
PrintWriter printWriter = new PrintWriter(fileWriter);
...
...
...
printWriter.println(sb.toString());