Having trouble with reading a txt file with one line and multiple variables

Question

(Fixed) I am new to Java (Which you probably will be able to tell by the inefficiency of code) and I am having a problem reading data from a text file.

Here is an example of how I create the file and write my data to the file.

  final String GString = "c:/GradeCalc/java/files";
        Path Gpath = Paths.get(GString);
        if (Files.notExists( Gpath )){
            try {
                Files.createDirectories(Gpath);
            } catch (IOException e2) {

                System.out.println(e2);
            }
        }

        final String Gfile = "Grades.txt";
         Path filePath = Paths.get(GString, Gfile);
         if (Files.notExists (filePath)) {

            try {
                Files.createFile (filePath);
            } catch (IOException e1) {

                System.out.println(e1);
            }
        }

        File gradeFile = filePath.toFile();
        try (PrintWriter out = new PrintWriter(
                new BufferedWriter(
                new FileWriter (gradeFile))))
        {

            if (BQ1Num != null){
            out.print(BQ1Num + "\t" );
            }else{
                out.print("0.0"+"\t");}
            if (BQ2Num != null){
                out.print(BQ2Num + "\t" );
                }else{
                    out.print("0.0"+"\t");}
            if (BQ3Num != null){
                out.print(BQ3Num + "\t" );
                }else{
                    out.print("0.0"+"\t");}
            if (BQ4Num != null){
                out.println(BQ4Num + "\t" );
                }else{
                    out.println("0.0"+"\t");}

                out.close ();
        }
            catch (IOException a)
            {
                System.out.println (a);
                }

Writting the data to the file seems to work perfectly. My problem arrises when I try to read that data and set it to a variable.

Here is an example of how I attempt to read the data from said file and assign the data to variables, then use those variables.

            try (BufferedReader in = new BufferedReader(new FileReader(Gfile))){

                String line = in.readLine();

                while(line != null){
                String[] columns = line.split("\t");
                BQ1RetrievedNum = columns [0];
                BQ2RetrievedNum = columns [1];
                BQ3RetrievedNum = columns [2];
                BQ4RetrievedNum = columns [3];

                 line = in.readLine();
                }
                }

            catch(IOException b){

                System.out.println(b);

            }




    if (BQ1RetrievedNum != null ){
    BQ1.setText("   Quarter 1  " +BQ1RetrievedNum+ "%");
    }
    if (BQ2RetrievedNum != null){
    BQ2.setText("   Quarter 2  " +BQ2RetrievedNum+ "%");
    }
    if (BQ3RetrievedNum != null){
    BQ3.setText("   Quarter 3  " +BQ1RetrievedNum+ "%");
    }
    if (BQ4RetrievedNum != null){
    BQ4.setText("   Quarter 4  " +BQ1RetrievedNum+ "%");
    }

Whenever I run my program, I get an ArrayIndexOutOfBoundsException. I've been searching for hours on how to fix this exception, but with no success.

Here is what the contents of the Grades.txt look like.

43.0 0.0 0.0 0.0

Here is the code for the fileReader that I now have after some editing.

try (BufferedReader in = new BufferedReader(new FileReader(Gfile))){

                String line = in.readLine();
                line = in.readLine();
                  String[]columns = line.split("\t");
                  for(int i=0;i<4;i++) {
                       if(i<columns.length) {
                          switch(i) {
                             case 1:  BQ1RetrievedNum = columns[0];
                                      break;
                             case 2:  BQ2RetrievedNum = columns[1];
                                      break;
                             case 3:  BQ3RetrievedNum = columns[2];
                                    break;
                             case 4:  BQ4RetrievedNum = columns [3];
                                    break;


                       }
                  }
                }
            }


            catch(IOException b){

                System.out.println(b);

            }

I keep getting a NullPointerException on this line:

 String[]columns = line.split("\t");

This is the code for my repaired reader.

 try (BufferedReader reader = Files.newBufferedReader(filePath, ENCODING )){
                  String line = null;
                  while ((line = reader.readLine()) != null) {

                System.out.println(line);
                String[]columns = line.split("/");
                BQ1RetrievedNum = "";
                BQ2RetrievedNum = "";
                BQ3RetrievedNum = "";
                BQ4RetrievedNum = "";

                System.out.println(columns.length);

                for(int i=0;i<4;i++) {
                    if(i<columns.length) {
                       switch(i) {
                          case 0:  BQ1RetrievedNum = columns[0];
                                   break;
                          case 1:  BQ2RetrievedNum = columns[1];
                                   break;
                          case 2:  BQ3RetrievedNum = columns[2];
                                 break;
                          case 3:  BQ4RetrievedNum = columns[3];
                                 break;


                       }
                    }
                }

                System.out.println("1: "+BQ1RetrievedNum);
                System.out.println("2: "+BQ2RetrievedNum);
                System.out.println("3: "+BQ3RetrievedNum);
                System.out.println("4: "+BQ4RetrievedNum);

                  }
                }



            catch(IOException b){

                System.out.println(b);

            }

Answer 1

See what is the length of the array

System.out.println(columns.length);

It may not contains expected number of values

EDIT: Following code work for me. Case values are edited.

String line = "43.0 0.0 0.0 0.0";
    String[]columns = line.split("\t");
    String output1 = "";
    String output2 = "";
    String output3 = "";
    String output4 = "";

    System.out.println(columns.length);

    for(int i=0;i<4;i++) {
        if(i<columns.length) {
           switch(i) {
              case 0:  output1 = columns[0];
                       break;
              case 1:  output2 = columns[1];
                       break;
              case 2:  output3 = columns[2];
                     break;
              case 3:  output4 = columns[3];
                     break;
           }
        }
    }

    System.out.println("1: "+output1);
    System.out.println("2: "+output2);
    System.out.println("3: "+output3);
    System.out.println("4: "+output4);

String.split("") doesn't throw NullPointerException

Answer 2

When you split according to \t:

String[] columns = line.split("\t");

You don't check the length of the returned array. You're getting the exception in one of these lines:

BQ1RetrievedNum = columns [0];
BQ2RetrievedNum = columns [1];
BQ3RetrievedNum = columns [2];
BQ4RetrievedNum = columns [3];

Before doing that, make sure the array has 4 elements.

---

You can do something like this:

for(int i=0;i<4;i++) {
   if(i<columns.length) {
      switch(i) {
         case 1:  BQ1RetrievedNum = columns[0];
                  break;
         case 2:  BQ2RetrievedNum = columns[1];
                  break;
         //...
      }
   }
}