Using Apache POI (java) to store excel cells in 2 dimensional array. Exception being returned despite me formatting all Excel cells as “text”

Question

I am extremely new to using Apache POI (and still new to Java too, infact!) and have come across an exception that I cannot determine how to fix.

Obviously you cannot store 2 different datatypes in an array, so I selected every column with data and converted the cell format to "Text" in Excel.

I then try to store this data in an array with the following:

String cellData[][] = new String[rows][cols];            
System.out.println(rows+" entries found with "+cols+" columns of data");

//iterate over every row and store cell data;
for(int i=0; i<rows; i++){
    row = worksheet.getRow(i);
    if(row != null){
        for(int j=0;j<cols;j++){
            cell = row.getCell(j);
            if(cell != null){
                try{
                    cellData[i][j] = cell.getStringCellValue();
                }catch(IllegalStateException e){
                    System.out.println("Cell data is not a string(text)");
                }
            }
        }
    }
}

The output from this is countless rows of "Cell data is not a string(text)", where am I going wrong here? Forgive me for any oversights I am also new to Stackoverflow and want to become a valued member of the community here too :) Thanks for your advice!

EDIT: Added e.printStackTrace() as requested.

at exceltesting.ExcelTesting.main(ExcelTesting.java:80)
java.lang.IllegalStateException: Cannot get a text value from a numeric cell
at org.apache.poi.hssf.usermodel.HSSFCell.typeMismatch(HSSFCell.java:648)
at org.apache.poi.hssf.usermodel.HSSFCell.getRichStringCellValue(HSSFCell.java:725)
at org.apache.poi.hssf.usermodel.HSSFCell.getStringCellValue(HSSFCell.java:708)

Interestingly enough, when I change it from cell.getStringCellValue() to cell.getNumericCellValue() the IllegalStateException then changes to "Cannot get a numerical value from a text cell"... I think the excel document, despite converting the cells to text is not actually changing to string data and passing them as their inherent data type? Thanks again

Answer 1

It seems that some of the cells are of Numeric type and some of them are of String Type. You need to handle Numeric Cell Types and String Cell types separately. I have not checked on my end, but sure... the following will work.

Cell cell = row.getCell(j); 
CellValue cellValue = evaluator.evaluate(cell);
switch (cellValue.getCellType()) {
    case Cell.CELL_TYPE_NUMERIC:
    cellData[i][j] = String.valueOf(cellValue.getNumberValue());
    break;
    case Cell.CELL_TYPE_STRING:
    cellData[i][j] = cell.getStringCellValue();
    break
}