Question

Consider the following method that is intended to determine if the double values d1 and d2 are close enough to be considered equal.
For example, given a tolerance of 0.001, the values 54.32271 and 54.32294 would be considered equal.

/** @return true if d1 and d2 are within the specified tolerance, 
 * false otherwise 
 */ 
public boolean almostEqual(double d1, double d2, double tolerance) 
{ 
 /* missing code */ 
}

Which of the following should replace /* missing code */ so that almostEqual will work as intended?

1. return ((d1 + d2) / 2) >= tolerance;

2. return ((d1 + d2) / 2) <= tolerance;

3. return Math.abs(d1 - d2) <= tolerance;

4. return (d1 - d2) <= tolerance;

5. return (d1 - d2) >= tolerance;

Answer 1

/** @return true if d1 and d2 are within the specified tolerance, 
 * false otherwise 
 */ 
public boolean almostEqual(double d1, double d2, double tolerance) 
{ 
    return Math.abs(d1 - d2) <= tolerance; 
}

return Math.abs(d1 - d2) <= tolerance;