使用Iterator遍历Sheet(POI)验证及解释结果有序性

test.xlsx:

Code:

package poi;

import static org.junit.Assert.*;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;

import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

@RunWith(value=Parameterized.class)
public class TestIterator {
    public TestIterator(Integer times) {
    }

    @Parameters
    public static Collection<Integer[]> init(){
        int times=200;
        Integer[][] parameters=new Integer[times][1];
        for (int i = 0; i < times; i++) {
            parameters[i][0]=i;
        }
        return Arrays.asList(parameters);
    }

    @Test
    public void  testItertor() throws IOException{
        List<Integer> expected=new ArrayList<Integer>();//rowNums.need to change according to demand
        for (int i = 0; i <=1 ; i++) {
            expected.add(i);
        }
        expected.add(3);
        expected.add(4);
        expected.add(6);

        List<Integer> actual=new ArrayList<Integer>();

        String filePath="/poi/test.xlsx";
        InputStream is=this.getClass().getResourceAsStream(filePath);
        Workbook wb=new XSSFWorkbook(is);
        Sheet sheet=wb.getSheetAt(0);
        for (Row row : sheet) {
            actual.add(row.getRowNum());
        }

        assertEquals(expected, actual);
    }
}

结果：通过验证。

源码解析：
org.apache.poi.xssf.usermodel.XSSFSheet
XSSFRow的存放数据结构：

 private TreeMap<Integer, XSSFRow> _rows;

    /**
     * @return an iterator of the PHYSICAL rows.  Meaning the 3rd element may not
     * be the third row if say for instance the second row is undefined.
     * Call getRowNum() on each row if you care which one it is.
     */
    @SuppressWarnings("unchecked")
    public Iterator<Row> rowIterator() {
        return (Iterator<Row>)(Iterator<? extends Row>) _rows.values().iterator();
    }

    /**
     * Alias for {@link #rowIterator()} to
     *  allow foreach loops
     */
    public Iterator<Row> iterator() {
        return rowIterator();
    }