Re: Urgent with this program, Pls help

[Jeannie Kaw]

Hi, I'm a idiot beginner in Java who have limited knowledge in this lang. Even so, I have 1 program which i not able to complete here. Here is the program aspects which i need to fulfill
Develop this program in Application which will perform the following functions:
Create a record contains 15 students and read the input from user.
1) We are free invited to enter the details of a Student with the name,
and enter the 3 Marks obtained in each 3 subjects.(like..Integer.parseInt(input);read their input
2) Calculate the average test score of each student.
3) Display the name of the student and test score according to their grade esTination, Credit, Pass
or Failed.
Fail=less than 40
Pass=less than 60 more than 40
Credit=Less than 70 more than 60
Destination=More than 70
4) Calculate and display the highest and lowest average score.
5) Develop in Application and print out the input from what user entered.
The report program should display in this format.
Roger Investigation Company
=====================================================================
S.No Name of Student Marks in 3 subject Average Grade
Mark1 Mark2 Mark3
=====================================================================
1. Mayer 65 79 24 56 PASS
2. Raite 55 78 69 67.33 CREDIT
3.......................................
4. .....................................
till 15 students.
=====================================================================
Highest Average = 67
Lowest Average = 56
Below is the source code which i completed, however it shd said incomplete.
-------------------------------------------------

//run this program as GoodLuck.java
 
import java.io.*;
import java.lang.*;
 
class GoodLuck
{
    
    public static void main(String args[]) throws IOException
    {
        String[] name  = new String[15];
        int[] students = new int[15];
        String Studname;
        int mark1, mark2, mark3;
        
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("Enter your Name:");
        System.out.println("Enter your mark1");
        System.out.println("Enter your mark2");
        System.out.println("Enter your mark3");
        
        for(int i = 0; i <= 14; i++)
        {
            Studname = input.readLine();
            mark1 = Integer.parseInt(input.readLine());
            mark2 = Integer.parseInt(input.readLine());
            mark3 = Integer.parseInt(input.readLine());
            name[i] = Studname;
            students[i] = mark1;
            students[i] = mark2;                              
            students[i] = mark3;
        }; 
        
        double highestAvg = -1.0;
        double lowestAvg = 101.0;    
        
        for (int i = 0; i < students.length; i++)
            for (int i = 0; i < students.length; i++)
            {
                double avg = (students[i].mark1 + students[i].mark2 +
                students[i].mark3) / 3.0;
                
                if (avg > highestAvg)
                    highestAvg = avg;
                
                if (avg < lowestAvg)
                    lowestAvg = avg;
                
                System.out.print (students[i].name + " "  +
                students[i]+ " "  +
                students[i]+ " " +
                students[i]+ " " + avg + " ");
                
                if (avg < 40)
                    System.out.println ("FAIL");
                else if (avg < 60)
                    System.out.println ("PASS");
                else if (avg < 70)
                    System.out.println ("CREDIT");
                else
                    System.out.println ("DISTINCTION");
            }
        
        System.out.println ();
        
        System.out.println ("Highest Average = " + highestAvg);
        System.out.println ("Lowest Average = "  + lowestAvg);
    }
    
}

--------------------------------------------------
My problem is that how i going to create array within array, I'm not able to figure at here. And i got errors when i javac...etc :
int[] incompatiable types.
Could someone show me how to work this program out. I'd appreciate your patience in solving this program.
Jeannie
[ May 02, 2002: Message edited by: Dirk Schreckmann ]

[frank davis]

int [][] marks = new int[15][3]
creates a multi-dimensional arrray called marks that holds 3 marks for 15 students.
mark[0][0] , mark [0][1], mark[0][2] would hold the first 3 marks for the first student, etc.
You could add another element to hold the average : int [][] marks = new int[15][4]

There's many solutions to this problem, some better. But your instructor should point those out.
[ April 30, 2002: Message edited by: herb slocomb ]

[Manfred Leonhardt]

Hi Jeannie,
I would start the project out using a Student class that handles the important stuff. For example:

class Student
{
  private String name;
  private int[] marks;
  private double average;
  public Student()
  {
    this( null, null );
  }
  public Student( String name )
  {
    this( name, null );
  }
  public Student( String name, int[] marks )
  {
    this.name = name;
    if( marks != null )
    {
      this.marks = marks;
    }
  }
  public void setName( String newName )
  {
    name = newName;
  }
  public void setMarks( int[] newMarks )
  {
    this.marks = newMarks;
    calcAverage();
  }
  public double getAverage()
  {
    return( average );
  }
  private calcAverage()
  {
    double sum = 0.;
    for( int i = 0; i < marks.length; ++i )
    {
     // ....
    }
    return( sum / marks.length );
  }
  public String toString()
  {
    //
    // This routine outputs to look like:
    //   mark1 mark2 mark3, average
    //
    return( formattedString );
  }
}

Then you could have your GoodLuck class look much cleaner. Something like:

public class GoodLuck
{
  private Student[] students;
  public GoodLuck()
  {
    students = new Student[15];
  }
  public askUserForInputs()
  {
    BufferedReader ...
    for( int i = 0; i < students.length; ++i )
    {
      // read name
      students[i] = new Student( name );
      int[] marks = new int[3];
      for( int j = 0; j < 3; ++j )
      {
        // read mark
        marks[i] = newMark;
      }
      students[i].setMarks( marks );
    }
  }
  public String toString()
  {
    // Loop though all students adding numbers in
    // front.
    for( ... )
    {
      outStr = # + ". " + students[i].toString()
      ...
    }
  }
  public double getHighestAverage()
  {
  }
  public double getLowestAverage()
  {
  }
  public static void main( String[] args )
  {
    GoodLuck gl = new GoodLuck();
    gl.askUserForInputs();
    System.out.println( gl );
    System.out.println( "Lowest: " + gl.getLowestAverage() );
    System.out.println( "Highest: " + gl.getHighestAverage() );
  }
}

Good Luck,
Manfred.

[Jeannie Kaw]

Okie, thks everybody. Again, I need u guys help.
1)So right now, I've paste the program elsewhere. Can u tell me how to println the user input, which meant once user input 1 student record:the name n 3 subjects marks, then the program will compute the result and print out with the heading.without going via to enter 4 students records then can be performed.
2) This program can compute/println 4 students records only, can i increase the array up to contains 15 students records?
How shd i modify the program?
3) Can i chose a option like say, the program will println only, when the user enter the command key. For instance:
show=println
insert=new student record
exit=escape.
I want to know is my program able to add on this option. How am i going to go abt?
Below is my source code, can someone amend on the code itself? Thks alot for your assistance.
==================================================

import java.io.*;
import java.math.*;
 
public class StudentProfileManager2 
{
    
    String[] students;
    int[][]  studentMarks;
    int numberOfStudents = 5;
    double[] studentsAvg;
    double minAvg = 0.0;
    double maxAvg = 0.0;
    
    public StudentProfileManager2(int numberOfStudents) 
    {
        this.numberOfStudents = numberOfStudents; 
        students = new String[numberOfStudents];
        studentMarks = new int[numberOfStudents][3];
        studentsAvg = new double[numberOfStudents];
    }
    
    public void getInput() throws Exception 
    {
        DataInputStream stream = new DataInputStream(System.in);
        double temp = 0; 
        
        for (int i = 0; i < numberOfStudents; ++i) 
        {
            System.out.print("enter student name:");
            students[i] = stream.readLine();
            
            for (int j = 0; j < 3; ++j) 
            {
                System.out.print("enter marks:");
                studentMarks[i][j] = Integer.parseInt(stream.readLine());
                temp += studentMarks[i][j];
            }
            
            studentsAvg[i] = (double) temp / 3.0;
            temp = 0; 
        }
    }
    
    public void showOutput() 
    {
        printHeader();
        
        for (int i = 0; i < numberOfStudents; ++i) 
        {
            System.out.print(formatString(new Integer((i + 1)).toString(), 4, ' ')); 
            System.out.print(formatString(students[i], 26, ' ')); 
            
            for (int j = 0; j < 3; ++j)
                System.out.print(formatString(
                    new Integer(studentMarks[i][j]).toString(), 9, ' '));
            
            System.out.print(formatString(roundup((float) studentsAvg[i]), 10, ' ')); 
            String grade = ""; 
            
            if (studentsAvg[i] < 40)
                grade = "FAIL";
            else if (studentsAvg[i] < 60)
                grade = "PASS"; 
            else if (studentsAvg[i] < 70)
                grade = "CREDIT"; 
            else
                grade = "DISTINCTION";
            System.out.println(formatString(grade, 12, ' ')); 
        }
        
        System.out.println(formatString("=", 78, '=')); 
        System.out.println("Lowest Average: "  + roundup((float) calMinAvg())); 
        System.out.println("Highest Average: " + roundup((float) calMaxAvg()) + "\n"); 
    }
    
    public double calMaxAvg() 
    {
        double max = 0; 
        
        if (studentsAvg != null) 
            if (studentsAvg.length > 0) 
                max = studentsAvg[0]; 
        
        for (int i = 0; i < studentsAvg.length; i++) { 
            if (studentsAvg[i] > max) 
                max = studentsAvg[i]; 
        }
        
        return max; 
    }
    
    public double calMinAvg() 
    {
        double min = 0; 
        
        if (studentsAvg != null) 
            if (studentsAvg.length > 0)
                min = studentsAvg[0];
        
        for (int i = 0; i < studentsAvg.length; i++) 
        {
            if (studentsAvg[i] < min) 
                min = studentsAvg[i]; 
        }
        
        return min; 
    }
    
    public void printHeader() 
    {
        System.out.println(formatString(" ", 24, ' ') + " Roger Investigation Company"); 
        System.out.println(formatString("=", 78, '=')); 
        System.out.println(formatString("SNo", 4, ' ') + 
                           formatString("Student Name", 30, ' ') + 
                           formatString("Marks in 3 Subject", 24, ' ') + 
                           formatString("Average", 10, ' ') + 
                           formatString("Grade", 12, ' ')); 
        System.out.println(formatString(" ", 30, ' ') + formatString("Mark 1", 9, ' ') + 
                           formatString("Mark 2", 9, ' ') + formatString("Mark 3", 9, ' ')); 
        System.out.println(formatString("=", 78, '=')); 
    }
    
    public static void main(String[] args) 
    {
        try 
        {
            StudentProfileManager2 stProfileMan = new StudentProfileManager2(5);
            
            stProfileMan.getInput();
            stProfileMan.showOutput();
        } 
        catch (Exception e) 
        {
            e.printStackTrace();
        }
    }
    
    public String formatString(String str, int length, char ch) 
    {
        String tempStr = ""; 
        boolean truncate = false; 
        
        if (str.length() < length) 
            tempStr = str; 
        else 
        {
            tempStr = str.substring(0, length); 
            
            truncate = true; 
        }
        
        if (str.length() < length && !truncate) 
        {
            for (int i = str.length(); i < length; i++) 
                tempStr = tempStr + ch; 
        }
        
        return tempStr; 
    }
    
    public String roundup(float value) 
    {
        BigDecimal d = new BigDecimal(value + "");
        
        d = d.setScale(2, BigDecimal.ROUND_HALF_UP); 
        
        return d.toString(); 
    }
    
}

[ May 02, 2002: Message edited by: Dirk Schreckmann ]