Load Excel Data to Java Class

DummyData.java

package test;

import java.util.ArrayList;
import java.util.List;

public class DummyData {
	List<List<Integer>> _data = new ArrayList<List<Integer>>();
	public void addRow (List<Integer> row) {
		_data.add(row);
	}
	public List<List<Integer>> getData () {
		return _data;
	}
	public List<Integer> getRowSum () {
		List<Integer> rowSum = new ArrayList<Integer>();
		for (List<Integer> row : _data) {
			Integer sum = 0;
			for (Integer i : row) {
				sum += i;
			}
			rowSum.add(sum);
		}
		return rowSum;
	}
}

TestExcelCalc.java

package test;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class TestExcelCalc {
	private static String CHAR_SET = "UTF-16LE";
	public static void main (String args[])
		throws Exception {
		// convert excel file to InputStream
		InputStream is = excelToInputStream("test.xlsx");
		// load InputStream to DummyData class
		DummyData dd = inputStreamToDummyData(is);
		// output some calculation result
		for (Integer i : dd.getRowSum()) {
			System.out.println(i);
		}
	}
	// convert excel file to InputStream
	private static InputStream excelToInputStream (String filePath)
		throws InvalidFormatException, IOException {
		// create workbook from file
		// and get first sheet
		Sheet sheet = new XSSFWorkbook(OPCPackage.open(new File(filePath)))
			.getSheetAt(0);
		StringBuilder sb = new StringBuilder("");
		// load all data into StringBuilder
		for (Row r : sheet) {
			for (Cell c : r) {
				if (sb.length() > 0)
					sb.append(" ");
				sb.append(new Double(c.getNumericCellValue()).intValue());
			}
		}
		// convert result String to InputStream
		return new ByteArrayInputStream(sb.toString().getBytes(CHAR_SET));
	}
	// load InputStream to DummyData class
	private static DummyData inputStreamToDummyData (InputStream is) {
		// create DummyData and Scanner
		DummyData dd = new DummyData();
		Scanner sc = new Scanner(is, CHAR_SET);
		// put data into DummyData class
		List<Integer> row = new ArrayList<Integer>();
		while (sc.hasNext()) {
			row.add(sc.nextInt());
			if (row.size() == 3) {
				dd.addRow(row);
				row = new ArrayList<Integer>();
			}
		}
		return dd;
	}
}