I'm implementing a set interface that requires my matrix to be immutable. I thought I had it correct but the test I'm running to change a value to 101 still changes that value.
public class NeilMatrix implements Matrix {
private final int[][] data;
private NeilMatrix(int[][] data) {
this.data = data;
}
public int getElement(int y, int x) {
return data[y][x];
}
public String toString() {
String strMatrix = "";
for(int i = 0; i < getRows(); i++) {
for(int j = 0; j < getColumns(); j++) {
strMatrix = strMatrix.concat(data[i][j] + " ");
}
strMatrix = strMatrix.concat("\n");
}
return strMatrix;
}
/**
* Entry point for matrix testing.
* @param args the command line arguments
*/
public static void main(String[] args) {
int[][] data1 = new int[0][0];
int[][] data2 = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
int[][] data3 = {{1, 4, 7}, {2, 5, 8}, {3, 6, 9}};
Matrix m1 = new NeilMatrix(data1);
Matrix m2 = new NeilMatrix(data2);
Matrix m3 = new NeilMatrix(data3);
//check for reference issues
System.out.println("m2 -->\n" + m2);
data2[1][1] = 101;
System.out.println("m2 -->\n" + m2);
}
}
This is the relevant piece of code. Shouldn't marking it final be enough to make sure you can't change it? If not, how do I do that? Please note that I cannot change the class to be private or add the final keyword to it so the other post suggested isn't helpful.
