MPAndroid 日期格式和解析丢失精度 [英] MPAndroid Date Formatting and Parsing Loses Precision

问题描述

我将 MPAndroid 库用于我的 android 应用程序的图表.我在条目中输入了一个很长的值.我的问题是，当我格式化 x 轴的值时，它使用浮点值而不是长值，因此它会失去精度.

I'm using the MPAndroid library for the graph of my android app. I have a long value inputted to the entry. My problem is that when I format the values of x axis, it uses float value instead of long so it loses precision.

这是我的图表入口代码:

Here is my code for the entry to the graph:

String dateString = "02/13/2019(11:23:45)";
long readingDate = 0;
try {
    SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy(kk:mm:ss)", Locale.US);
    Date date = sdf.parse(dateString);
    readingDate = date.getTime();
    } catch (ParseException e) {
         e.printStackTrace();
    }
SensorData.add(new Entry(readingDate, 1.5);

这是我格式化 x 轴的代码:

Here is my code for formatting the x axis:

private class XAxisValueFormatter implements IAxisValueFormatter {

    @Override
    public String getFormattedValue(float value, AxisBase axis) {
        String dateString = new SimpleDateFormat("MM/dd/yyyy(kk:mm:ss)", Locale.US).format(value);
        return dateString;
    }
}

我该如何解决这个问题?

How can I fix this problem?

推荐答案

一个可能的解决方案是让你的第一个点保持 0 值.

One of possible solutions would be to make your first point hold 0 value.

基本上，您需要从 Entry 的每个新 x 值中减去 start_timestamp，这样图表将从 0 值而不是时间戳开始.

Basically you need subtract start_timestamp from every new x value of Entry so chart will be started from 0 value and not of timestamp.

例如.

让我们假设 start_timestamp 变量保存您的第一个数据点时间戳.

Let's assume start_timestamp variable holds your first timestamp of datapoints.

要添加新条目，请使用:

To add new entry use:

SensorData.add(new Entry(readingDate - start_timestamp, 1.5);

要格式化 x 值，您只需将 start_timestamp 添加到提供的 x 值.

To format x value you just add start_timestamp to provided x value.

这篇关于MPAndroid 日期格式和解析丢失精度的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！