The code gets cut out by freedium, so here is all the code after doing a ctrl-a then ctrl-c:

``` import java.util.Random;

// Main class public class SimpleDemoGA {

Population population = new Population();
Individual fittest;
Individual secondFittest;
int generationCount = 0;

public static void main(String[] args) {

    Random rn = new Random();

    SimpleDemoGA demo = new SimpleDemoGA();

    //Initialize population
    demo.population.initializePopulation(10);

    //Calculate fitness of each individual
    demo.population.calculateFitness();

    System.out.println("Generation: " + demo.generationCount + " Fittest: " + demo.population.fittest);

    //While population gets an individual with maximum fitness
    while (demo.population.fittest < 5) {
        ++demo.generationCount;

        //Do selection
        demo.selection();

        //Do crossover
        demo.crossover();

        //Do mutation under a random probability
        if (rn.nextInt()%7 < 5) {
            demo.mutation();
        }

        //Add fittest offspring to population
        demo.addFittestOffspring();

        //Calculate new fitness value
        demo.population.calculateFitness();

        System.out.println("Generation: " + demo.generationCount + " Fittest: " + demo.population.fittest);
    }

    System.out.println("\nSolution found in generation " + demo.generationCount);
    System.out.println("Fitness: "+demo.population.getFittest().fitness);
    System.out.print("Genes: ");
    for (int i = 0; i < 5; i++) {
        System.out.print(demo.population.getFittest().genes[i]);
    }

    System.out.println("");

}

//Selection
void selection() {

    //Select the most fittest individual
    fittest = population.getFittest();

    //Select the second most fittest individual
    secondFittest = population.getSecondFittest();
}

//Crossover
void crossover() {
    Random rn = new Random();

    //Select a random crossover point
    int crossOverPoint = rn.nextInt(population.individuals[0].geneLength);

    //Swap values among parents
    for (int i = 0; i < crossOverPoint; i++) {
        int temp = fittest.genes[i];
        fittest.genes[i] = secondFittest.genes[i];
        secondFittest.genes[i] = temp;

    }

}

//Mutation
void mutation() {
    Random rn = new Random();

    //Select a random mutation point
    int mutationPoint = rn.nextInt(population.individuals[0].geneLength);

    //Flip values at the mutation point
    if (fittest.genes[mutationPoint] == 0) {
        fittest.genes[mutationPoint] = 1;
    } else {
        fittest.genes[mutationPoint] = 0;
    }

    mutationPoint = rn.nextInt(population.individuals[0].geneLength);

    if (secondFittest.genes[mutationPoint] == 0) {
        secondFittest.genes[mutationPoint] = 1;
    } else {
        secondFittest.genes[mutationPoint] = 0;
    }
}

//Get fittest offspring
Individual getFittestOffspring() {
    if (fittest.fitness > secondFittest.fitness) {
        return fittest;
    }
    return secondFittest;
}


//Replace least fittest individual from most fittest offspring
void addFittestOffspring() {

    //Update fitness values of offspring
    fittest.calcFitness();
    secondFittest.calcFitness();

    //Get index of least fit individual
    int leastFittestIndex = population.getLeastFittestIndex();

    //Replace least fittest individual from most fittest offspring
    population.individuals[leastFittestIndex] = getFittestOffspring();
}

}

//Individual class class Individual {

int fitness = 0;
int[] genes = new int[5];
int geneLength = 5;

public Individual() {
    Random rn = new Random();

    //Set genes randomly for each individual
    for (int i = 0; i < genes.length; i++) {
        genes[i] = Math.abs(rn.nextInt() % 2);
    }

    fitness = 0;
}

//Calculate fitness
public void calcFitness() {

    fitness = 0;
    for (int i = 0; i < 5; i++) {
        if (genes[i] == 1) {
            ++fitness;
        }
    }
}

}

//Population class class Population {

int popSize = 10;
Individual[] individuals = new Individual[10];
int fittest = 0;

//Initialize population
public void initializePopulation(int size) {
    for (int i = 0; i < individuals.length; i++) {
        individuals[i] = new Individual();
    }
}

//Get the fittest individual
public Individual getFittest() {
    int maxFit = Integer.MIN_VALUE;
    int maxFitIndex = 0;
    for (int i = 0; i < individuals.length; i++) {
        if (maxFit <= individuals[i].fitness) {
            maxFit = individuals[i].fitness;
            maxFitIndex = i;
        }
    }
    fittest = individuals[maxFitIndex].fitness;
    return individuals[maxFitIndex];
}

//Get the second most fittest individual
public Individual getSecondFittest() {
    int maxFit1 = 0;
    int maxFit2 = 0;
    for (int i = 0; i < individuals.length; i++) {
        if (individuals[i].fitness > individuals[maxFit1].fitness) {
            maxFit2 = maxFit1;
            maxFit1 = i;
        } else if (individuals[i].fitness > individuals[maxFit2].fitness) {
            maxFit2 = i;
        }
    }
    return individuals[maxFit2];
}

//Get index of least fittest individual
public int getLeastFittestIndex() {
    int minFitVal = Integer.MAX_VALUE;
    int minFitIndex = 0;
    for (int i = 0; i < individuals.length; i++) {
        if (minFitVal >= individuals[i].fitness) {
            minFitVal = individuals[i].fitness;
            minFitIndex = i;
        }
    }
    return minFitIndex;
}

//Calculate fitness of each individual
public void calculateFitness() {

    for (int i = 0; i < individuals.length; i++) {
        individuals[i].calcFitness();
    }
    getFittest();
}

} ```

A fully compiled language on the other hand (e.g. C), is run directly on the machine's CPU after the source code is compiled into machine code.

This interpreter is a software program that reads the code, analyzes it, and performs the actions specified in the code at runtime. An interpreter translates source code into machine code on the fly, executing it line by line or statement by statement.

The JVM is essentially an interpreter for the intermediate-level byte code generated after compiling java code.