MPAndroidChart:饼图或自定义标签中的负值 [英] MPAndroidChart: negative values in pie chart or custom labels

问题描述

在我的Android应用程序中，我必须以饼图显示我的收入和支出金额.费用金额为负数.金额类型为float.因此，可以使用MPAndroidChart库在饼图中显示负值和正值吗?

In my Android application I have to show my income and expense amounts in a piechart. The expense amounts will be negative. The amounts are of type float. So is it possible to display both negative and positive values in a pie chart using MPAndroidChart library?

我尝试使用一些负和正整数值，结果令人难以置信.饼图的行为会像拉米纸牌或照明屏幕一样疯狂.

I have tried with some negative and positive integer values and the result is horible. The pie-chart will behave crazy like a rummy board or illumination screen.

如果我不能在饼图中使用负值，即使实际值是正数，是否也可以将标签显示为负数?

If I can't have negative values in a pie chart, is it possible to show the labels in negative by even though the actual values are positive?

推荐答案

您实际上是在问如何自定义 IValueFormatter .

You are essentially asking how to customise the labels on an MPAndroidChart chart. This can be done easily by writing your own implementation of the interface IValueFormatter.

IValueFormatter有一种您需要实现的方法:

IValueFormatter has one method that you need to implement:

getFormattedValue(float value, Entry entry, int dataSetIndex, ViewPortHandler viewPortHandler)`

您可以使用方法的参数将所需的标签构造为String.您想要在前面加减号-"，因此只需执行以下操作:

You use the parameters of the method to construct the label you want as a String. You want a minus sign "-" in front so you simply do this:

return "-" + mFormat.format(value) + " %";

这是完整的实现:

public class NegativePercentFormatter implements IValueFormatter

    protected DecimalFormat mFormat;

    public NegativePercentFormatter() {
        mFormat = new DecimalFormat("###,###,##0.0");
    }


    public NegativePercentFormatter(DecimalFormat format) {
        this.mFormat = format;
    }

    @Override
    public String getFormattedValue(float value, Entry entry, int dataSetIndex, ViewPortHandler viewPortHandler) {
        return "-" + mFormat.format(value) + " %";
    }
}

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