利用jxl 读取文件夹下的多张excl表，excl表较多时报错数组越界，较少时不报错，结果正确，求大神解释

package jv; 
import java.io.File;  
import java.io.FileInputStream;  
import java.io.FileNotFoundException;  
import java.io.FileWriter;  
import java.io.IOException;  
import java.io.InputStream;  
import java.io.PrintWriter;  
import jxl.Cell;  
import jxl.Sheet;  
import jxl.Workbook;  
import jxl.read.biff.BiffException;  
public class Get {  
    public static void main(String[] args) {  
        Get obj = new Get();  
        // 此处路径指定文件夹  
        File file = new File("E:/DFYY");  
        if (file.isDirectory()) {  
            File[] files = file.listFiles();  
            for (File f : files)  
                // 读取子目录下的Excel文件  
                if (f.isDirectory()) {  
                    File[] subfiles = f.listFiles();  
                    for (File fi : subfiles) {  
                        // 只读取Excel文件  
                        if (fi.getName().indexOf(".xls") > 0) {  
                            obj.readExcelWriteDat(fi);  
                        }  
                    }  
                } else {  
                    // 只读取Excel文件
                    if (f.getName().indexOf(".xls") > 0) {  
                        obj.readExcelWriteDat(f);  
                    }  
                }  
        }  
    }  
  
    public void readExcelWriteDat(File file) {  
        // 创建文件输出流  
        FileWriter fw = null;  
        PrintWriter out = null;      
        try {   
            // 创建输入流
            InputStream is = new FileInputStream(file.getAbsolutePath());  
            // jxl提供的Workbook类  
            Workbook wb = Workbook.getWorkbook(is); 
            // 每一张工作簿中只有两张工作表，故用wb.getSheet(0),wb.getSheet(1);
                Sheet sheetPhase = wb.getSheet(0);
                Sheet sheetRes = wb.getSheet(1);
                Cell[] cell0 = sheetPhase.getColumn(0);
                //以单元格名字命名文件名
                for(int k=1;k<sheetPhase.getColumns();k++){
                	String newfileName =sheetPhase.getCell(k, 0).getContents();
                	fw = new FileWriter(file.getParent()+"/"+newfileName + ".dat");
                    out = new PrintWriter(fw);  
                    //获得工作表的某一列的值
                    Cell[] cellPhase = sheetPhase.getColumn(k);
                    Cell[] cellRes = sheetRes.getColumn(k);
                    //组合不同工作表同一列值输出
                    for(int i =1;i<sheetPhase.getRows();i++){
                    	out.print(cell0[i].getContents()+"  "+cellPhase[i].getContents()+"  "
                    			+cellRes[i].getContents());
                    	out.print("\r\n");
                    }
                    try {  
                        // 关闭流  
                        out.close();  
                        fw.close();  
                        out.flush();  
                    } catch (IOException e) {  
                        e.printStackTrace();  
                    }
                }  
        } catch (FileNotFoundException e) {  
            e.printStackTrace();  
        } catch (BiffException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        } 
    }  
}

错误提示：Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 10at jxl.read.biff.SheetImpl.getColumn(SheetImpl.java:490)at jv.Get.readExcelWriteDat(Get.java:57)at jv.Get.main(Get.java:27)