Store cell values to Object - automation

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.