Java lang null pointer exception

[newcoder1010]

Hello, 

Hello,

I am a beginner of java. I wrote this code. When I run it in eclipse, I get an error: java lang null point exception. It does not tell me which line I have wrong code. Please advise on how to fix it. 
 

	    	// Open the Excel file
	    	FileInputStream fis = new FileInputStream(file);

	    	// Access the required test data sheet
	    	HSSFWorkbook wb = new HSSFWorkbook(fis);
	    	HSSFSheet sheet = wb.getSheet("Sheet1");
            int  TotalCol;
            int  TotalRow;

           // TotalCol = 0;
            TotalRow = sheet.getLastRowNum();
            TotalCol = sheet.getRow(0).getLastCellNum();
   	        System.out.println("row " + TotalRow +  " col " +  TotalCol);

			int resultcol;
			resultcol = 0;
	    	for(int col = 0;col<=TotalCol;col++){

	    	     HSSFRow row1 = sheet.getRow(0);
	    	     System.out.println("column names " + row1.getCell(col).toString() );
	    	 	if("result".equalsIgnoreCase(row1.getCell(col).toString().trim()))
				{
	    	 		resultcol = col;
		    	     System.out.println("result column number " + resultcol );

				}
	    		
	    	}

 

[Ingolme]

You're going to have to tell me what line its on, but usually that means you tried to use an object that wasn't initialized.

[newcoder1010]

I am not a good debugger. I need to learn how to debug in eclipse. 

First, I commented all code.

Then I un-commented one line at a time and ran it. 

I dont have any error until I reach this line:

       System.out.println("column names " + row1.getCell(col).toString() );

Even though I get the error, it still printed all the messages from the above code. 
 

Edited June 17, 2017 by newcoder1010

[newcoder1010]

This block of the code causing it. Please advise. 

	    	     //System.out.println("column names " + row1.getCell(col).toString() );
//	    	 	if("result".equalsIgnoreCase(row1.getCell(col).toString().trim()))
//				{
//	    	 		resultcol = col;
//		    	     System.out.println("result column number " + resultcol );
//
//				}

 

[Ingolme]

The console should tell you exactly on what line the exception occurred.

[newcoder1010]

It did not give me the line no.

https://drive.google.com/open?id=1FtMZVH2qm8zFAsONqFRWjvB6QRFlqZ8iXd2EbCRd-Tc

[Ingolme]

It says in your editor that the exception occurred in LoginTest.java at line 77.

You should check to see if the variable row1 is null.

[RyanLincoln]

On 6/17/2017 at 10:57 PM, newcoder1010 said:

Hello, 

Hello,

I am a beginner of java. I wrote this code. When I run it in eclipse, I get an error: java lang null point exception. It does not tell me which line I have wrong code. Please advise on how to fix it. 
 

	    	// Open the Excel file
	    	FileInputStream fis = new FileInputStream(file);

	    	// Access the required test data sheet
	    	HSSFWorkbook wb = new HSSFWorkbook(fis);
	    	HSSFSheet sheet = wb.getSheet("Sheet1");
            int  TotalCol;
            int  TotalRow;

           // TotalCol = 0;
            TotalRow = sheet.getLastRowNum();
            TotalCol = sheet.getRow(0).getLastCellNum();
   	        System.out.println("row " + TotalRow +  " col " +  TotalCol);

			int resultcol;
			resultcol = 0;
	    	for(int col = 0;col<=TotalCol;col++){

	    	     HSSFRow row1 = sheet.getRow(0);
	    	     System.out.println("column names " + row1.getCell(col).toString() );
	    	 	if("result".equalsIgnoreCase(row1.getCell(col).toString().trim()))
				{
	    	 		resultcol = col;
		    	     System.out.println("result column number " + resultcol );

				}
	    		
	    	}

 

Have you tried to debug your code?