Monthly Archives: February 2022

2-d Arrays OOP Project

Let’s write a program for something like PowerSchool that helps organize a seating chart for students.  There is a tester file at the page’s bottom.

First class : Student  , from https://mrmonline.org/student-class/

Class SeatingChart

This class mainly manages a 2-d  array of student objects. Note: an empty seat in the chart will be designated by a null value.

Constructor(s)

  • public SeatingChart(int period, String teacher, String _rosterName) Initializes parameters to respective arguments and creates a 2-d array  of null objects with default dimensions DEFAULT_ROWS , DEFAULT_COLS
  • public SeatingChart(int period, String teacher, String _rosterName, Student[][] table)

Methods:

public int countEmptySeats() ; //returns the number of empty seats. As noted earlier, an empty seat is represented by a null value in the 2-d array of student s

Student[][] getStudentChart()  @returns chart

public int[] indexOf(Student stu);  returns a 2 element array representing the row and column position of stu in chart ; [-1][-1] should be returned if stu is not in chart

public boolean setSeat(int row, int col, Student stu) -  places Student Stu  at that row and column .  This can only be done if there is no student in that location. If a student already inhabits that row and column then the method should return false and not make any changes to chart .

public void swap(Student s1, Student s2) // this swaps the locations of s1 and s2

public Student getStudent(int row, int col) returns the student at the given row and col ; or null if the seat is empty

public void removeStudentAt(int row, int col)   sets value of object at  row  and  col  to  null 

public boolean equals(SeatingChart other) // returns true if all aspects of  other are equivalent to self.

public String toString(); //follow the conventions we have been using

public Student oldest() // returns the student object with the greatest age

Extra credit

public void randomize() // this randomizes the chart. This extra credit method is only available if you first meet with me to explain what I expect out of this.

 

SeatingChartTesterv2.java :

import java.util.Arrays;

public class SeatingChartTesterv2
{
    public SeatingChartTesterv2()
    {
    Student amelia = new Student("Amelia", 17);
    Student antonioooo = new Student("antonioooo", 14);

    SeatingChart period3 = new SeatingChart(3, "Mr. M", "A Days");

    int correct = 0;
    int wrong  = 0;

    Student[][] currentChart = period3.getStudentChart();
    if(currentChart[0].length == SeatingChart.DEFAULT_COLS && currentChart.length == SeatingChart.DEFAULT_ROWS)
        correct++;
    else
        {
        p("Default constructor's 2-d Array incorrect dimensions");
        wrong++;
        }

    boolean result = period3.setSeat(5,6, amelia );

    if(result)
        correct++;
    else
        {
        p("setSeat() return value error");
        }

    Student[][] chartNow = period3.getStudentChart();
    if(chartNow[5][6] == amelia)
    {
        correct++;

// Student getStudent(int row, int col)
        if( period3.getStudent(5,6) == amelia)
            correct++;
        else
            {
            p("Error, looks like getStudent() ");
            }

    }    
    else
        {
        p("A) erorr, probably from setSeat() or getStudentChart() ");
        wrong++;
        }



    int[] locaxn = period3.indexOf(amelia);
    if(locaxn[0]==5 && locaxn[1] == 6)
        correct++;
    else
        {
        p("B) setSeat() or indexOf() error");
        wrong++;
        }
    result =period3.setSeat(5,6, antonioooo );

    if(result== false)
        correct++;
    else
        {
        p("C) setSeat() return value error");
        wrong++;
        }

    String st = period3.toString();

    if(st.indexOf("SeatingChart") == 0)
        correct++;
    else{
        p("toString() error. ClassName should be first characters");
        wrong++;
    }

    if(st.contains("Mr. M"))
        correct++;
    else{
        p("toString() error. ");
        wrong++;
    }
   
    if(st.contains("A Days"))
        correct++;
    else{
        p("toString() error. ");
        wrong++;
    }
//new seating chart
Student tim = new Student("tim");
Student[][]  someKids= {
                    { new Student(), tim , null},
                    { new Student(), new Student("joe", 12), null, null,null},
                    { new Student(), new Student("alfjdj", 999), null},
                    { new Student(), new Student("sss", 5), null},
                        };

    SeatingChart period4 = new  SeatingChart(4, "MR M", "p4", someKids);

//make sure that someKids was actually set to the chart

Student[][] p4Chart = period4.getStudentChart();
if( Arrays.equals(p4Chart , someKids))
    correct++;
else
    {
    wrong++;
    p("Error . Looks like you did not correctly instantiate 2-d array in constructor ");
    }




    boolean isCorrect = true;
Student oldest  = null ;
    try{
    oldest = period4.oldest();
    }
    catch(NullPointerException e){
        isCorrect = false;    
            p("Error @ oldest(), you cannot call .getAge() on a null object");
        }
   
if(isCorrect && oldest != null && oldest.getAge() ==999)
correct++;
else
    {
    wrong++;
    p("Error @ oldest()");
    }
    locaxn = period4.indexOf(tim);
  
    
    System.out.print(locaxn[0]);
    System.out.print(locaxn[1]);


    if(locaxn[0]==0 && locaxn[1] == 1)
        correct++;
    else
        {
        p("A incorrect student. Could be constructor");
        wrong++;
        }
       
if ( period4.getStudent(0,1) == tim )
        correct++;
    else
        {
        p("B incorrect student. Could be constructor, getStudent()");
        wrong++;
        }
    ///


int emptySeats = period4.countEmptySeats();

if(emptySeats == 6)
        correct++;
    else
        {
        p("countEmptySeats() error");
        wrong++;
        }


Student vinnie = new Student("Vinnie", 16);
Student yuya = new Student("Yuya", 18);
Student[][]  p5Kids = {
                        { yuya, vinnie}
                        };

SeatingChart period5 = new  SeatingChart(4, "MR M", "p4", p5Kids);

int[]  yuyaLocation_befo = period5.indexOf(yuya);
int[]  vinniaLocation_befor = period5.indexOf(vinnie);



period5.swap(vinnie,yuya) ;
int[]  yuyaLocation_now = period5.indexOf(yuya);
int[]  vinniaLocation_now = period5.indexOf(vinnie);

if( yuyaLocation_now[0] == vinniaLocation_befor[0] &&  yuyaLocation_now[1] == vinniaLocation_befor[1]  )
        correct++;
    else
        {
        p("Error Swap");
        wrong++;
        }
if( vinniaLocation_now[0] == yuyaLocation_befo[0] &&  vinniaLocation_now[1] == yuyaLocation_befo[1]  )
        correct++;
    else
        {
        p("Error Swap");
        wrong++;
        }
////
//


Student rany = new Student("rany", 16);
Student[][]  p6Kids = {
                        { rany, null,null,null},
                        { null, null,null,null}
                        };

SeatingChart period6 = new  SeatingChart(4, "MR M", "p4", p6Kids );
period6.removeStudentAt(0,0);
if( period6.getStudent(0,0) == null )
        correct++;
    else
        {
        p("Error @ removeStudentAt() ");
        wrong++;
        }

if( period5.equals(period6) == false)
        correct++;
    else
        {
        p("A Error @ equals() ");
        wrong++;
        }
if( period5.equals(period5) )
        correct++;
    else
        {
        p("B Error @ equals() ");
        wrong++;
        }

SeatingChart period6Clone = new  SeatingChart(4, "MR M", "p4", p6Kids );

if( period6.equals(period6Clone) )
        correct++;
    else
        {
        p("C Error @ equals() ");
        wrong++;
        }




p("----------------------------------");
p("Correct : " + correct);
p("Wrong : " + wrong);


    }//end of constructor

void p(String x) { System.out.println(x); }
void p(int x) { System.out.println(x); }
void p(boolean x) { System.out.println(x); }
void p(double x) { System.out.println(x); }
void p2d(int[] x) { System.out.println(x[0] + ",  " + x[1]); }

}
SeatingChartTester