@Override
    public CharSequence flatten(long timeMillis, int logLevel, String tag, String message) {
        return Long.toString(timeMillis)
                + '|' + LogLevel.getShortLevelName(logLevel)
                + '|' + tag
                + '|' + message;
    }
Simply join the timestamp, log level, tag and message together.

@since 1.3.0
android/android_framework/base/src/main/java/com/elvishew/xlog/flattener/DefaultFlattener.java