[SoapUI] error in using Java language to determine whether Excel cells are empty or null in SoapUI

When I fetch Excel data, I first determine if the cell is "":

If (cellvalue! = "") {
Listnumber.add (i);
Cellvalues.add (cellvalue.trim ());
}

has been error, because the original also took no error, so entered the misunderstanding, did not expect that the cell format in Excel has Changed.

Cause: because the cell format is general, the data is error-free when the cell is Empty. I didn't determine if the cell was Null.

Two workarounds:

1: change the cell format of Excel to number, string to Text.

2: Change the judging code, if (cellvalue! = "" "&& cellvalue! = Null)

[SoapUI] error in using Java language to determine whether Excel cells are empty or null in SoapUI