The ValueFormatter interface

Available since v1.6.2 - changed (improved) in v2.1.4

The ValueFormatter interface can be used to create custom-made formatter classes that allow to format values within the chart (from DataSets) in a specific way before drawing them.

For using the ValueFormatter, simply create a new class and let it implement the interface and return whatever you want to be displayed from the getFormattedValue(...) method.

Example of a custom formatter

public class MyValueFormatter implements ValueFormatter {

    private DecimalFormat mFormat;
    
    public MyValueFormatter() {
        mFormat = new DecimalFormat("###,###,##0.0"); // use one decimal
    }
    
    @Override
    public String getFormattedValue(float value, Entry entry, int dataSetIndex, ViewPortHandler viewPortHandler) {
        // write your logic here
        return mFormat.format(value) + " $"; // e.g. append a dollar-sign
    }
}

Then, set your formatter to the ChartData or DataSet object:

// usage on whole data object
lineData.setValueFormatter(new MyValueFormatter());

// usage on individual dataset object
lineDataSet.setValueFormatter(new MyValueFormatter());

Predefined custom Formatters

• LargeValueFormatter: Can be used for formatting large values > "1.000". It will turn values like "1.000" into "1k", "1.000.000" will be "1m" (million), "1.000.000.000" will be "1b" (billion) and values like one trillion will be e.g. "1t". It does not support numbers with decimal digits like "1.000,5".
• PercentFormatter: Used for displaying a "%" sign after each value with 1 decimal digit. Especially useful for the PieChart.