Thread: I cannot figure out what the errors mean nor how to correct them. Please help.

Here is the input file "test.txt" is:

5

55 65 75 85 95

Here is my code:

import java.io.Console;
import java.util.*;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.IOException;
 
public class Project{
   public static void main(String[] args)
        throws FileNotFoundException, IOException 
   {
 
        //Console console = System.console();
        System.out.println("----------------------------------------------------------------------\n");
 
        BufferedReader inputFile = new BufferedReader(
            new FileReader("test.txt")
        );
 
        while (inputFile.ready()) {
            String[] line = inputFile.readLine().split("\\s+");
            int length = Integer.parseInt(line[0]);
        }
 
        // Vectors for each letter grade  
        Vector A = new Vector(100);
        Vector B = new Vector(100);
        Vector C = new Vector(100);
        Vector D = new Vector(100);
        Vector F = new Vector(100);
 
 
        // For loop that repeats to program.
        for (int j = 1; j < (length + 1); j++) {
 
            //String a = console.readLine("What is your grade # %s ", j + 1);
            int NewGrade = Integer.parseInt(line[j]);
 
            NewGrade = line[j];
 
 
            if (NewGrade >= 90) {
                A.addElement(new Integer(NewGrade));
            }
            else if (80 <= NewGrade && NewGrade <= 89) {
                B.addElement(new Integer(NewGrade));
            } 
            else if (70 <= NewGrade && NewGrade <= 79) {
                C.addElement(new Integer(NewGrade));
            } 
            else if (60 <= NewGrade && NewGrade <= 69) {
                D.addElement(new Integer(NewGrade));
            } 
            else {
                F.addElement(new Integer(NewGrade));
            }
 
        }
 
 
        System.out.println("Number of people who made an 'A': " + A.size());
        System.out.println("Number of people who made an 'B': " + B.size());
        System.out.println("Number of people who made an 'C': " + C.size());
        System.out.println("Number of people who made an 'D': " + D.size());
        System.out.println("Number of people who made an 'F': " + F.size());
 
 
        System.out.println("\n----------------------------------------------------------------------");
    }
}

And here are the error messages:


C:\Users\Jared\Desktop\Project>javac Project.java
Project.java:34: error: cannot find symbol
for (int j = 1; j < (length + 1); j++) {
^
symbol: variable length
location: class Project
Project.java:37: error: cannot find symbol
int NewGrade = Integer.parseInt(line[j]);
^
symbol: variable line
location: class Project
Project.java:39: error: cannot find symbol
NewGrade = line[j];
^
symbol: variable line
location: class Project
Note: Project.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
3 errors

C:\Users\Jared\Desktop\Project>

Hello.
You need to learn about scope of a variable in java.
This link may be of help. Variable Scope

Also, it shall help us if we know what exactly your program is doing. Based on that we can help you better.

Syed.

for (int j = 1; j < (length + 1); j++)

length of what?

Originally Posted by syedbhai

Hello.
You need to learn about scope of a variable in java.
This link may be of help. Variable Scope

Also, it shall help us if we know what exactly your program is doing. Based on that we can help you better.

Syed.

I apologize, I forgot to explain the program. Basically it's reading a list of grades from a file and putting a letter grade to them. It outputs the total number of each letter grade. The first number in the text file is the number of grades.[COLOR="Silver"]

--- Update ---

It's the length variable that was declared earlier in the code.

Originally Posted by syedbhai

Hello.
You need to learn about scope of a variable in java.
This link may be of help. Variable Scope

Also, it shall help us if we know what exactly your program is doing. Based on that we can help you better.

Syed.

Okay, here is my new code:

import java.io.Console;
import java.util.*;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.IOException;
 
public class Project{
   public static void main(String[] args)
        throws FileNotFoundException, IOException 
   {
        int length;
        String[] line;
        //Console console = System.console();
        System.out.println("----------------------------------------------------------------------\n");
 
        BufferedReader inputFile = new BufferedReader(
            new FileReader("test.txt")
        );
 
        while (inputFile.ready()) {
            line = inputFile.readLine().split("\\s+");
            length = Integer.parseInt(line[0]);
        }
 
        // Vectors for each letter grade  
        Vector A = new Vector(100);
        Vector B = new Vector(100);
        Vector C = new Vector(100);
        Vector D = new Vector(100);
        Vector F = new Vector(100);
 
 
        // For loop that repeats to program.
        for (int j = 1; j < (length + 1); j++) {
 
            //String a = console.readLine("What is your grade # %s ", j + 1);
            int NewGrade = Integer.parseInt(line[j]);
 
            //NewGrade = line[j];
 
 
            if (NewGrade >= 90) {
                A.addElement(new Integer(NewGrade));
            }
            else if (80 <= NewGrade && NewGrade <= 89) {
                B.addElement(new Integer(NewGrade));
            } 
            else if (70 <= NewGrade && NewGrade <= 79) {
                C.addElement(new Integer(NewGrade));
            } 
            else if (60 <= NewGrade && NewGrade <= 69) {
                D.addElement(new Integer(NewGrade));
            } 
            else {
                F.addElement(new Integer(NewGrade));
            }
 
        }
 
 
        System.out.println("Number of people who made an 'A': " + A.size());
        System.out.println("Number of people who made an 'B': " + B.size());
        System.out.println("Number of people who made an 'C': " + C.size());
        System.out.println("Number of people who made an 'D': " + D.size());
        System.out.println("Number of people who made an 'F': " + F.size());
 
 
        System.out.println("\n----------------------------------------------------------------------");
    }
}

Here are my errors:


C:\Users\Jared\Desktop\Project>javac Project.java
Project.java:12: error: illegal start of expression
protected int length;
^
Project.java:13: error: illegal start of expression
protected String[] line;
^
2 errors

C:\Users\Jared\Desktop\Project>

Did you post the right code?
There is no "protected" keyword anywhere in your class. Just to be correct I compiled your source code in your most recent post.
This is the compile-time error I get:

Project.java:35: variable length might not have been initialized
        for (int j = 1; j < (length + 1); j++) {
                             ^
Project.java:38: variable line might not have been initialized
            int NewGrade = Integer.parseInt(line[j]);

Syed.

I'm not sure what happened. I must have copied the wrong thing. The compile error that you got, was what I got.

This:

Project.java:35: variable length might not have been initialized
for (int j = 1; j < (length + 1); j++) {
^
Project.java:38: variable line might not have been initialized
int NewGrade = Integer.parseInt(line[j]);

Those lines are very descriptive in the error itself. Both are initialized within the while loop but what happens if the condition in the while loop is not met? Those values will never be initialized and when you try to use them it won't know what to do. Best practice is to initialize the variables as soon as possible then modify them as you need to.

I initialized them before the while loop.

There is a difference between initializing a variable and creating a variable.

// Create variables
int firstInt; // This variable was just created not initialized
int secInt = 100; // This variable was created an initialized
 
firstInt = 500; // This variable has now been initialized

Another word for "created" that is used more commonly is Java is "declared."

Thanks everyone for the help. I finished the program and got it working. Here is what I ended up with. If anyone has suggestions or tips, please let me know.

My code:

import java.io.Console;
import java.util.*;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.*;
 
public class Project{
   public static void main(String[] args)
        throws FileNotFoundException, IOException 
   {
        // Initializing Variables.
        int length = 0;
        String[] line = {};
 
        // Just for looks.
         System.out.println("\n" + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178
          + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178
           + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178
            + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + "\n");
 
        // Reading the number of grades and the actual grades from the file.
        BufferedReader inputFile = new BufferedReader(new FileReader("test.txt"));
        length = Integer.parseInt(inputFile.readLine());
        while (inputFile.ready()) {
            line = inputFile.readLine().split("\\s+");
        }
 
        // Vectors for each range of grades  .
        // [0-24]
        Vector A = new Vector(100);
        // [25-49]
        Vector B = new Vector(100);
        // [50-74]
        Vector C = new Vector(100);
        // [75-99]
        Vector D = new Vector(100);
        // [100-124]
        Vector E = new Vector(100);
        // [125-149]
        Vector F = new Vector(100);
        // [150-174]
        Vector G = new Vector(100);
        // [175-200]
        Vector H = new Vector(100);
        // This one if for any number that happens to not fit within a category.
        Vector I = new Vector(100);
 
 
        // For loop that repeats the program.                         
        for (int j = 0; j < length; j++) {
 
            // Initializing NewGrade Variable.
            int NewGrade = Integer.parseInt(line[j]);
 
            // Logic for categorizing the grades.
            if (0 <= NewGrade && NewGrade <= 24) {
                A.addElement(new Integer(NewGrade));
            }
            else if (25 <= NewGrade && NewGrade <= 49) {
                B.addElement(new Integer(NewGrade));
            } 
            else if (50 <= NewGrade && NewGrade <= 74) {
                C.addElement(new Integer(NewGrade));
            } 
            else if (75 <= NewGrade && NewGrade <= 99) {
                D.addElement(new Integer(NewGrade));
            } 
            else if (100 <= NewGrade && NewGrade <= 124) {
                E.addElement(new Integer(NewGrade));
            }
            else if (125 <= NewGrade && NewGrade <= 149) {
                F.addElement(new Integer(NewGrade));
            }
            else if (150 <= NewGrade && NewGrade <= 174) {
                G.addElement(new Integer(NewGrade));
            }
            else if (175 <= NewGrade && NewGrade <= 200) {
                H.addElement(new Integer(NewGrade));
            }
            else {
                I.addElement(new Integer(NewGrade));
            }
 
        }
 
        // Printing the groups of grades out to the screen.
        System.out.println("[0 - 24]: " + A.size());
        System.out.println("[25 - 49]: " + B.size());
        System.out.println("[50 - 74]: " + C.size());
        System.out.println("[75 - 99]: " + D.size());
        System.out.println("[100 - 124]: " + E.size());
        System.out.println("[125 - 149]: " + F.size());
        System.out.println("[150 - 174]: " + G.size());
        System.out.println("[175 - 200]: " + H.size());
 
        // Just for looks.
        System.out.println("\n" + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178
             + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178
              + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178
               + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178 + (char)178);
    }
}