Java 使用StringBuilder組裝字元串

下面這個例子來自SpringBoot源碼，這裡是要列印程式啟動的時間這樣的字元串，需要拼裝的資訊有 程式名字，啟動時長，JVM時長。

private StringBuilder getStartedMessage(StopWatch stopWatch) {
    StringBuilder message = new StringBuilder();
    message.append("Started ");
    message.append(getApplicationName());
    message.append(" in ");
    message.append(stopWatch.getTotalTimeSeconds());
    try {
      double uptime = ManagementFactory.getRuntimeMXBean().getUptime() / 1000.0;
      message.append(" seconds (JVM running for " + uptime + ")");
    }
    catch (Throwable ex) {
      // No JVM time available
    }
    return message;
  }