Actor entity[] = new Actor[15]; // All the entities.
...
double time[] = new double[entity.length]; // Keep track of translation times for all entities for collision.
...
update {
// Set velocity vectors for all entities.
for (int i = 1; i < entity.length; i++)
entity.updateMovements(/* various variables */);

// Collision tests.
for (int i = 0; i < entity.length; i++) {
for (int j = i + 1; j < entity.length; j++) {
double tempTime = collisionTest(entity, entity[j]);

// Entities' velocities multiplied by smallest calculated time.
if (tempTime < time)
time = tempTime;

if (tempTime < time[j])
time[j] = tempTime;
}
}

// Actual movement.
for (int i = 0; i < entity.length; i++) {
entity.move(time);
time = 1.0;
}
}

public double collisionTime(Actor A, Actor B) {   Get relative velocity from A to B (treat B as stationary). -> vel           if (vel.magnitude == 0.0)      return 1.0; // Actors stationary to each other.           Get relative position from A to B. -> pos           Get minimum possible distance between A and B: sum of their radii. -> minDist           if ((vel.magnitude + minDist) <= pos.magnitude)      return 1.0; // Actors would not reach each other.           Get unit vector of vel. -> unitVel           Get dot product of unitVel and pos. -> dotprod   if (dotprod > 0.0)      return 1.0; // Actors either moving parallel to or away from each other.           /* dotprod is also the projection of pos onto vel.  dotprod is the distance      along vel that's closest to B.      Therefore, the shortest distance between B and vel is the square root of      the squares of the magnitude of pos and dotprod. */           Get shortest distance between B and vel, (distance between B and its      projection onto vel). -> F           // F is shortest distance A would ever get to B as they travel.           if (F > minDist)      return 1.0; // A wouldn't touch B.           // F makes right triangle with minDist and a third value of T.   Use pythagoras to get T.           // If no such right triangle exists, T^2 would be negative.   if (T^2 < 0.0)      return 1.0;           Get the real distance, which is dotprod - T. -> realDist           if (vel.magnitude <= realDist)      return 1.0; // Final distance greater than relative velocity.           double time = realDist / vel.magnitude;           if (time < 0.0)      return 0.0;   else if (time > 1.0)      return 1.0;   else      return time;}