Error in methods( Class container)

Question

This is my Book class. how to write a list that count books by classification in Library class???
class Book
     //attributes that holds data for each book in the library
     private String BookName;
     private char Classification;
     private int NumPages;
     private String SerialNum;
     //constructor with arguments that has the same name as the class name
     public Book(String inName, char inClassf, int inNumPg, String inSerialNo)
          BookName = inName;
          Classification = inClassf;
          NumPages = inNumPg;
          SerialNum = inSerialNo;
     //Mutator method to set name of the book
     public boolean setBookname(String newName)
     if (newName != null && newName.length() >0) 
          BookName = newName;   
          return true; 
          else 
          return false; 
     //Mutator method to set the classification of the book
     public boolean setClassF(char newClassf)
          if(newClassf == 'F' || newClassf == 'f'&& newClassf == 'N' || newClassf == 'n' && newClassf == 'R' || newClassf == 'r')
               Classification = newClassf;
               return true;
          else
               return false;
     //Mutator method to set number of pages of the book
     public boolean setNumpg(int newNumPg)
          if(newNumPg > 0)
               NumPages = newNumPg;
               return true;
          else
               return false;
     //Mutator method to set the serial number of the book
     public boolean setSerialno(String newSerialNo)   
          if ((newSerialNo != null) && (newSerialNo.length() == 4))       
               SerialNum = "A" + newSerialNo;           
               return true;       
          else           
               return false;   
     //Accessor method to get name of the book
     public String getBookname()
          return BookName;
     //Accessor method to get classification of the book
     public char getClassF()
          return Classification;
     //Accessor method to get number of pages of the book
     public int getNumpg()
          return NumPages;
     //Accessor method to get serial number of the book
     public String getSerialno()
          return SerialNum;
     //Method to calculate the book tax based on the number of pages
     public double bookTax()
          double totalTax = 0.0;   
          if(NumPages <= 100)
               totalTax = NumPages * 0.1; 
          else if     (NumPages > 100)
               totalTax = (NumPages * 0.1) + ((NumPages-100) * 0.15);   
          return totalTax;
     // toString method returns a String containing information about the object's
     // current data
     public String toString()
           return "\nName of book: "+getBookname()+"\nClassification: "+getClassF()+"\nNumber of pages: "+getNumpg()+"\nSerial Number: "+getSerialno();
here is my code in Library class
// Method that uses getClassF method of Book class and calculate books by
// classification.
    public String classificationsHeld()
         int held = 0;
         for(int i = 0; i < currentHolding; i++)
         held += lib.getClassF();

Answer 1

You'll probably have to get a lot more specific about the problem you're having in order to get much help.