Given:
public class ComputeSum {
public int x;
public int y;
public int sum;
public ComputeSum (int nx, int ny) {
x = nx; y =ny;
updateSum();
}
public void setX(int nx) { x = nx; updateSum();}
public void setY(int ny) { x = ny; updateSum();}
void updateSum() { sum = x + y;}
}
This class needs to protect an invariant on the sum field.
Which three members must have the private access modifier to ensure that this invariant is maintained?