Programming and Problem Solving with Java

CASE STUDY^607

Internal Data Representation:Earlier, we said that an array is the ideal implementation
structure for a matrix. In many languages, we would have to include the number of
rows and number of columns as data fields in the Matrixclass. Java, however, provides
them automatically as instance variables in the array object. Let’s represent the
numeric values in the matrices as double; this strategy allows us to handle the largest
range of values.

public classMatrix
{
// Private data field
private double[][] matrix;
...
}

Class Name: Matrix Superclass: Object Subclasses:

Responsibilities Collaborations

Create itself (rows, columns) None

Know value at (row, col) None

return double

Know number of rows None

return int

Know number of columns

return Matrix

None

return int

Subtract (two) from self None

return Matrix

Multiply self times (two) None

return Matrix

Print (outFile) PrintWriter

Add self to (two) None

Set a value at (row, col, value) None