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Java lang null pointer exception


newcoder1010
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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 );

				}
	    		
	    	}

 

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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 by newcoder1010
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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 );
//
//				}

 

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  • 3 years later...
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?

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