Add Trendline to Chart and Read Trendline Equation in Excel in Java

This article demonstrates how to add Trendline to an Excel chart and read the equation of the Trendline using Spire.XLS for Java.

Add Trendline

import com.spire.xls.*;
import com.spire.xls.core.IChartTrendLine;

import java.awt.*;

public class AddTrendline {
    public static void main(String[] args){
        //Create a Workbook instance
        Workbook workbook = new Workbook();
        //Load the Excel file
        workbook.loadFromFile("test.xlsx");

        //Get the first chart in the first worksheet
        Chart chart = workbook.getWorksheets().get(0).getCharts().get(0);

        //Add a Trendline to the first series of the chart
        IChartTrendLine trendLine = chart.getSeries().get(0).getTrendLines().add(TrendLineType.Linear);

        //Set Trendline name
        trendLine.setName("Linear(Series1)");
        //Set line type and color
        trendLine.getBorder().setPattern(ChartLinePatternType.DashDot);
        trendLine.getBorder().setColor(Color.blue);
        //Set forward and backward value
        trendLine.setForward(0.5);
        trendLine.setBackward(0.5);
        //Set intercept value
        trendLine.setIntercept(5);

        //Display equation on chart
        trendLine.setDisplayEquation(true);
        //Display R-Squared value on chart
        trendLine.setDisplayRSquared(true);

        //Save the result file
        workbook.saveToFile("AddTrendline.xlsx", ExcelVersion.Version2013);
    }
}

Add Trendline to Chart and Read Trendline Equation in Excel in Java

Read Trendline equation

import com.spire.xls.Chart;
import com.spire.xls.Workbook;
import com.spire.xls.core.IChartTrendLine;

public class ReadEquationOfTrendline {
    public static void main(String[] args){
        //Create a Workbook instance
        Workbook workbook = new Workbook();
        //Load the Excel file
        workbook.loadFromFile("AddTrendline.xlsx");

        //Get the first chart in the first worksheet
        Chart chart = workbook.getWorksheets().get(0).getCharts().get(0);

        //Read the equation of the first series of the chart
        IChartTrendLine trendLine = chart.getSeries().get(0).getTrendLines().get(0);
        String equation = trendLine.getFormula();
        System.out.println("The equation is: " + equation);
    }
}

Add Trendline to Chart and Read Trendline Equation in Excel in Java