从Java中的字符串单元格获取数值

Question

I am learning reading and writing excel files with java. i have written code for creating the bar chart from the excel sheet and im facing the error that " Cannot get a NUMERIC value from a STRING cell". i am not understanding how to resolve the issue .. Is anyone could help me getting resolve the issue .

here is code .

> import java.io.*; import java.util.*;
> 
> import org.jfree.data.*; import org.jfree.chart.JFreeChart; import
> org.jfree.chart.ChartFactory; import org.jfree.chart.ChartUtilities;
> import org.jfree.chart.plot.PlotOrientation; import
> org.apache.poi.hssf.usermodel.HSSFRow; import
> org.apache.poi.hssf.usermodel.HSSFCell; import
> org.apache.poi.hssf.usermodel.HSSFSheet; import
> org.apache.poi.hssf.usermodel.HSSFWorkbook; import
> org.jfree.data.category.DefaultCategoryDataset; import
> org.apache.poi.ss.usermodel.Cell;
> 
> 
> public class BARCHART{ public static void main(String[]args){ short
> a=0;  short b=1;  int i=0;  ArrayList<String> list1=new
> ArrayList<String>(); ArrayList<Integer> list2=new
> ArrayList<Integer>();
> 
> String x; int y=0;  String filename ="Student Grading Report.xls"; 
> 
> 
> if(filename != null && !filename.equals("")){ try{  FileInputStream fs
> =new FileInputStream(filename);  HSSFWorkbook wb = new HSSFWorkbook(fs);  for(int k = 0; k < wb.getNumberOfSheets(); k++){ 
> int j=i+1;  HSSFSheet sheet = wb.getSheetAt(k);  int rows =
> sheet.getPhysicalNumberOfRows();  for(int r = 1; r < rows; r++){ 
> HSSFRow row = sheet.getRow(r);  int cells =
> row.getPhysicalNumberOfCells();  HSSFCell cell1 = row.getCell(a); 
> 
> x =(String) cell1.getStringCellValue();  HSSFCell cell2 =
> row.getCell(b);  y =(int) cell2.getNumericCellValue(); 
> 
> list1.add(new String(x)); list2.add(new Integer(y));  }  i++;  } 
> }catch(Exception e){  System.out.println(e);
> 
> }
> 
> } DefaultCategoryDataset dataset = new DefaultCategoryDataset();
> for(int j=0;j<list2.size();j++){
> dataset.setValue((double)list2.get(j), "Marks",
> list1.get(j).toString()); } JFreeChart chart =
> ChartFactory.createBarChart("BarChart","Marks", "St_Id", dataset, 
> PlotOrientation.VERTICAL, false,true, false); try {
> ChartUtilities.saveChartAsJPEG(new File("chart.jpg"), chart,400, 300);
> } catch (IOException e) { System.out.println("Problem in creating
> chart."); } } }

anyone one who can help me in resolving such issue? Thankyou :)

Answer 1

If you try to save a string into a double or integer in Java, it will reject this as it is a strongly typed language. You can instead use the lines of code

Integer.parseInt(*desiredVariable*)

or

Double.parseDouble(*desiredVariable*)

to change these strings into the right data type.

Answer 2

   HSSFCell yourCell = sheet.getRow(row).getCell(column);
   yourCell.setCellType(Cell.CELL_TYPE_STRING);
   String data = yourCell.getStringCellValue();