Store cell values to Object

Question

I'm currently new to TestNG using java. I'm trying to read the values from an excel using poi apache 4.0

public static void read2dRowExcelFile2(String filePath) throws IOException {

    try {
        FileInputStream fis = new FileInputStream(new File(filePath));
        HSSFWorkbook wb = new HSSFWorkbook(fis);
        HSSFSheet sheet = wb.getSheet("PerLocation");

        Object[][] tableArr = new String[sheet.getLastRowNum() + 1][];
        int arrNo1 = 0;
        for (int i = 1; i <= sheet.getLastRowNum(); i++) {
            Row row = sheet.getRow(i);              
            int arrNo2 = 0;
            for (int j = 0; j < row.getLastCellNum(); j++) {
                String cellValue = row.getCell(j).getStringCellValue();
                System.out.println(acellValue);
                //tableArr[arrNo1][arrNo2] = cellValue;
                System.out.println("test");
                arrNo2++;
            }
            
            arrNo1++;
        }
        
        wb.close();
        
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Code above displays the values on the console. My goal is to store those values to an Object. Something like [{London, Blue},{Tokyo,Yellow},{Manila,Red}] so I can pass them to a dataProvider

If I run the code above, it displays : London BLue Tokyo Yellow Manila Red

But If i uncomment this line :

//tableArr[arrNo1][arrNo2] = cellValue;

The output is only : London

03-08-19 : After I enabled stacktrace, it says : java.lang.NullPointerException which pertains to this code :

tableArr[arrNo1][arrNo2] = cellValue;

Answer 1

From your code,

Object[][] tableArr = new String[sheet.getLastRowNum() + 1][]; 

At the time of initialization of array, your are setting size of first dimension but not the second . You need to initialize array for second dimension before you access it.

Refer below example:

    public static void main(String[] args) {
        //read rows size
        int numOfRows = 3;
        String[][] tableArr = new String[numOfRows][];

        for (int row = 0; row <3; row++) {
            //read columns size
            int numOfColsInRow = 3;
            tableArr[row]=new String[numOfColsInRow];              
            for (int col = 0; col < 3; col++) {
                String cellValue = "cell-" + row+""+col;//read cell value
                tableArr[row][col] = cellValue;
            }
        }

        for(String[] row: tableArr) {
            System.out.println(Arrays.toString(row));
        }
    }

Running above code with generate expected output:

[cell-00, cell-01, cell-02]
[cell-10, cell-11, cell-12]
[cell-20, cell-21, cell-22]

To reproduce your problem you can try commenting line which initialize array for second dimension in the code and you will see Exception in thread "main" java.lang.NullPointerException .

        //tableArr[row]=new String[numOfColsInRow];              

To avoid all such issues you also can check if any exiting TestNG data-provider extension satisfies your need.