public void test_subclassing() throws Exception {
// http://b/2502231
// Ensure that Random's constructors call setSeed by emulating the active ingredient
// from the bug: the subclass' setSeed had a side-effect necessary for the correct
// functioning of next.
class MyRandom extends Random {
public String state;
public MyRandom() {
super();
}
public MyRandom(long l) {
super(l);
}
@Override
protected synchronized int next(int bits) {
return state.length();
}
@Override
public synchronized void setSeed(long seed) {
state = Long.toString(seed);
}
}
// Test the 0-argument constructor...
MyRandom r1 = new MyRandom();
r1.nextInt();
assertNotNull(r1.state);
// Test the 1-argument constructor...
MyRandom r2 = new MyRandom(123L);
r2.nextInt();
assertNotNull(r2.state);
}
// roulette wheel method
public void select(Chromosome[] population, Chromosome[] newPopulation, int populationSize)
throws FitnessSumZeroException {
double p, sum = 0;
// find total _fitness of the population
for (int mem = 0; mem < populationSize; mem++) {
sum += population[mem].getFitness();
}
if (sum == 0) throw new FitnessSumZeroException();
// calculate relative _fitness
for (int mem = 0; mem < populationSize; mem++) {
population[mem].rfitnessSet(population[mem].getFitness() / sum);
}
population[0].cfitnessSet(population[0].rfitnessGet());
if (Debug.flag) {
System.out.println("mem=0, _cfitness=" + population[0].cfitnessGet());
}
// calculate cumulative _fitness
for (int mem = 1; mem < populationSize; mem++) {
population[mem].cfitnessSet(
population[mem - 1].cfitnessGet() + population[mem].rfitnessGet());
if (Debug.flag) {
System.out.println("mem=" + mem + ", _cfitness=" + population[mem].cfitnessGet());
}
}
// finally select survivors using cumulative _fitness.
for (int i = 0; i < populationSize; i++) {
p = MyRandom.dblRandom();
if (p < population[0].cfitnessGet()) {
population[0].copyChromosome(newPopulation[i]);
if (Debug.flag) {
System.out.println("p=" + p + ", selected 0");
}
} else {
for (int j = 0; j < populationSize; j++) {
if (p >= population[j].cfitnessGet() && p < population[j + 1].cfitnessGet()) {
// note that population[populationSize-1].cfitnessGet()
// is 1.0, so j+1 never gets as big as populationSize
population[j + 1].copyChromosome(newPopulation[i]);
if (Debug.flag) {
System.out.println("p=" + p + ", selected " + (j + 1));
}
}
}
}
}
}
