Java, How to find specific value from two dimensional array of doubles?

Question

I need to calculate the price between two locations, I have the following data structure which holds the price between areas:

                  Washington  Niagra Falls  New York
Washington        0,          6.30,         8.30
Niagra Falls      5.30,       0   ,         5.30
New York          3.20,       4.30,         0

How do I create a method that it will find the value in the two dimensional array based on the String X and String Y Locations?

Here is the code I have so far:

String Location X = "Washington";
String Location Y = "New York";

String XY = {"Washington", "Niagara Falls", "New York"}; 
//Cost of the trips
double[][] prices = { 
    {0,    6.30, 8.30},
    {5.30, 0,    5.30},
    {3.20, 4.30, 0   },
};

In the above case Washington -> New York should be 8.30 .

Method should be something like this:

public double calculateFees(String X, String Y){
    //add code here.

    double fares;
 return fares;
}

Answer 1

You'd need to figure out which array indices would apply.

public double calculateFees(String X, String Y){
    int xArrIdx=0;
    for(xArrIdx=0; xArrIdx<XY.length; xArrIdx++){
        if(XY[xArrIdx].equals(X)) break;

    }
    for(yArrIdx=0; yArrIdx<XY.length; yArrIdx++){
        if(XY[yArrIdx].equals(Y)) break;

    }

    return prices[xArrIdx][yArrIdx];
}  

Making this handle cases where X or Y aren't in the array is left as an exercise to the reader.

Also make sure prices and XY are accessible from calculateFees . XY should also be a String[] , not a String .

Answer 2

Get the index of the X from XY , say i .

Get the index of Y from XY , say j .

Get the fare using, prices[i][j] .

You might need to loop over the array XY testing for the given string each twice. You can save time by using a HashMap from String to Integer index instead.