Question

I need help with the last method listed in the problem: Implement a class Grid that stores measurements in a rectangular grid. The grid has a given number of rows and columns, and a description string can be added for any grid location. Supply the following constructor and methods:

public Grid(int numRows, int numColumns)

public void add(int row, int column, String description)

public String getDescription(int row, int column)

public ArrayList getDescribedLocations()

Here, Location is an inner class that encapsulates the row and the column of a grid location.

This is what I have so far for the last method:

import javax.xml.stream.Location;
import java.util.ArrayList;
/**
 * The object class for the Grid element which will store the measurement and description
 * */
class gridElement {
    int measurement;
    String description;
}

public class Grid {
    //Instance Variables
    private int row;
    private int column;
    private gridElement[][] gridArray;

//Constructors
    /**
     * Created a Grid with the provided rows and columns
     * @param numRows for the grid
     * @param numColumns for the grid
     * */
    public Grid (int numRows, int numColumns) {

    gridArray = new gridElement[numRows][numColumns];
    }
//Methods
    /**
     * A method to add a description to certain rows + columns
     * @param row in the grid
     * @param column in the griod
     * @param description of the location on the grid
     * */
    public void add(int row, int column, String description) {
        gridArray[row][column].description = description;
    }
    /**
     * A method to get the description
     * @param row of the grid
     * @param column of the grid
     * @return gridArray row & column description
     * */
    public String getDescription(int row, int column) {

        return this.gridArray[row][column].description;
    }
    /**
     * A method that returns the row and column of the grid elements which have a description
     * */
    public ArrayList<Location> getDescribedLocations(){
        int k = 0;
        ArrayList<Location> location = new ArrayList<>();

        for ( int i = 0; i < row; i++) {
            for (int j = 0; j < column; j++) {
                if (gridArray[i][j].description != null) {
                    location.add(" i = " + i + " and j = " + j);
                }
            }
        }
        return location;

    }
}

I can't figure out how to display the row and columns that are filled with descriptions when the arraylist type is of "Location"

ERROR:

add(javax.xml.stream.Location)in ArrayList cannot be applied to(java.lang.String)

Answer 1

// import javax.xml.stream.Location; this is an interface

import java.util.ArrayList;

/**

* The object class for the Grid element which will store the measurement and description

* */

class gridElement

{

       int measurement;

       String description;

}

public class Grid {

      

       //Instance Variables

    private int row;

    private int column;

    private gridElement[][] gridArray;

      

    // create an inner class Location that encapsulates the row and the column of a grid location.

       class Location

       {

             private int row;

             private int col;

            

             public Location(int row, int col)

             {

                    this.row = row;

                    this.col = col;

             }

            

             public int getRow()

             {

                    return row;

             }

            

             public int getCol()

             {

                    return col;

             }

       }

      

       //Constructors

    /**

     * Created a Grid with the provided rows and columns

     * @param numRows for the grid

     * @param numColumns for the grid

     * */

    public Grid (int numRows, int numColumns) {

       gridArray = new gridElement[numRows][numColumns];

    }

   

//Methods

    /**

     * A method to add a description to certain rows + columns

     * @param row in the grid

     * @param column in the griod

     * @param description of the location on the grid

     * */

    public void add(int row, int column, String description) {

        gridArray[row][column].description = description;

    }

   

    /**

     * A method to get the description

     * @param row of the grid

     * @param column of the grid

     * @return gridArray row & column description

     * */

    public String getDescription(int row, int column) {

        return this.gridArray[row][column].description;

    }

   

    /**

     * A method that returns the row and column of the grid elements which have a description

     * */

    public ArrayList<Location> getDescribedLocations(){

        //int k = 0;

        ArrayList<Location> location = new ArrayList<>();

        for ( int i = 0; i < row; i++) {

            for (int j = 0; j < column; j++) {

                if (gridArray[i][j].description != null) {

                    location.add(new Location(i,j));

                }

            }

        }

        return location;

    }

}