Develop Reference

How to choose pass instance method to use to a method in Java

I have a method that sorts a List by different criteria and returns the name (an instance variable) of the one with maximum value. In case more than one instance is having the maximum, all of their names should be concatenated.
Let's say I have Class A as follows.
Class A {
...
String getName(){...}
int getValue1() {...}
int getValue2() {...}
...
int getValueN() {...}
...
}
I have a List<A> listToSort. I would normally sort this list as listToSort.sort(Comparator.comparing(A::getValue1)) or listToSort.sort(Comparator.comparing(A::getValue2)), so on and so forth. Then get the ones sharing the maximum value.
In a method I believe this should be done as:
String getMaxString (Comparator c) {
listToSort.sort(c);
...
}
and send Comparator.comparing(A.getValueX) as parameter to call it with different methods. (X here indicates an arbitrary number for the getValue function).
However, I need to also return other instances sharing the same values
I will need to pass the Class methods to my method and call on instances as:
String getMaxString (Comparator c) {
listToSort.sort(c);
int maxValue = listToSort.get(listToSort.size() - 1).getValueX();
String maxString = listToSort.get(listToSort.size() - 1).getName();
for (int i = listToSort.size() - 2; i >= 0; i--) {
if (listToSort.get(i).getValueX()() == maxValue) {
maxString += ", " + listToSort.get(i).getName();
}
}
return maxString;
}
How would I pass this method to call on instances here? Or do I need to consider another way?
Edit:
I have a list of Courses as List<Course> mylist where a course can be simplified as:
Class Course {
private String name;
private int capacity;
private int students;
...
//bunch of getters.
}
My task is to return Strings for the course(es) with maximum capacity, the course(es) with maximum registered students, the course(es) with most difficulty, the maximum filled percentage, the course(es) with the maximum number of TAs etc...
Edit 2:
As requested in the comment section.
List of
Course a (name "a", capacity 10, students 5)
Course b (name "b", capacity 20, students 5)
Course c (name "c", capacity 30, students 0)
Sorting based on capacity should return "c"
Sorting based on students should return "a b"

You can pass the getter method and create the Comparator in getMaxString:
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.function.Function;
public class Foo {
static class AClass {
private final String name;
private final int value1;
private final int value2;
String getName() { return name; }
int getValue1() { return value1; }
int getValue2() { return value2; }
public AClass(String name, int value1, int value2) {
this.name = name;
this.value1 = value1;
this.value2 = value2;
}
}
static String getMaxString(Function<AClass,Integer> f, List<AClass> listToSort) {
listToSort.sort(Comparator.comparing(f));
int maxValue = f.apply(listToSort.get(listToSort.size() - 1));
String maxString = listToSort.get(listToSort.size() - 1).getName();
for (int i = listToSort.size() - 2; i >= 0; i--) {
if (f.apply(listToSort.get(i)) == maxValue) {
maxString += ", " + listToSort.get(i).getName();
}
}
return maxString;
}
public static void main(String[] args) {
List<AClass> list = new ArrayList<>();
list.add(new AClass("a", 1,2));
list.add(new AClass("b", 1,2));
list.add(new AClass("c", 2,1));
list.add(new AClass("d", 2,1));
System.out.println(getMaxString(AClass::getValue1, list));
System.out.println(getMaxString(AClass::getValue2, list));
}
}
As Tim Moore suggested above, it isn't necessary to sort the list (which has cost O(n*log n)), we can traverse it twice:
static String getMaxString2(ToIntFunction<AClass> f, List<AClass> listToSort) {
int maxValue = listToSort.stream().mapToInt(f).max().orElseThrow();
return listToSort.stream()
.filter(a -> maxValue == f.applyAsInt(a))
.map(AClass::getName)
.collect(Collectors.joining(", "));
}
Note that you should test your code with an empty list.

It's useful to look at the type signature for Comparator.comparing, because it sounds like you want to do something similar:
static <T,U extends Comparable<? super U>> Comparator<T> comparing(Function<? super T,? extends U> keyExtractor)
The interesting part is the type of keyExtractor. Roughly speaking, it's a function from the type of the object you're comparing, to the type of the field you want to use for the comparison. In our case, these correspond to the A class and Integer. Because these types are fixed in this example, you can declare a method with a signature like this:
String getMaxString(Function<A, Integer> property)
With the existing algorithm, it can be used this way:
String getMaxString(Function<A, Integer> property) {
listToSort.sort(Comparator.comparing(property));
int maxValue = property.apply(listToSort.get(listToSort.size() - 1));
String maxString = listToSort.get(listToSort.size() - 1).getName();
for (int i = listToSort.size() - 2; i >= 0; i--) {
if (listToSort.get(i).getValueN() == maxValue) {
maxString += ", " + listToSort.get(i).getName();
}
}
return maxString;
}
However, it isn't necessary or efficient to sort the entire list in order to determine the maximum elements, as this can be determined by iterating through the list once:
String getMaxString(Function<A, Integer> property) {
int maxValue = Integer.MIN_VALUE;
StringBuilder maxString = new StringBuilder();
for (A element : listToSort) {
int currentValue = property.apply(element);
if (currentValue > maxValue) {
// there is a new maximum, so start the string again
maxString = new StringBuilder(element.getName());
maxValue = currentValue;
} else if (currentValue == maxValue) {
// equal to the existing maximum, append it to the string
if (maxString.length() > 0) {
maxString.append(", ");
}
maxString.append(element.getName());
}
// otherwise, it's less than the existing maximum and can be ignored
}
return maxString.toString();
}
Either way, you can call it using the same method reference syntax:
getMaxString(A::getValueN)

Time complexity O(n) - only one iteration through the dataset.
Hope it'll help.
If something will be unclear fill free to raise a question.
Main
public class MaxClient {
public static void main(String[] args) {
Comparator<A> comp = Comparator.comparingInt(A::getVal1);
List<A> items = List.of(new A(1, 8), new A(2, 8), new A(5, 8), new A(5, 27), new A(3, 8));
items.stream()
.collect(new GetMax(comp))
.forEach(System.out::println);
}
}
Custom collector GetMax
public class GetMax implements Collector <A, Deque<A>, Deque<A>> {
private final Comparator<A> comp;
public GetMax(Comparator<A> comp) {
this.comp = comp;
}
#Override
public Supplier<Deque<A>> supplier() {
return ArrayDeque::new;
}
#Override
public BiConsumer<Deque<A>, A> accumulator() {
return (stack, next) -> {
if (!stack.isEmpty() && comp.compare(next, stack.peekFirst()) > 0) stack.clear();
if (stack.isEmpty() || comp.compare(next, stack.peekFirst()) == 0) stack.offerLast(next);
};
}
#Override
public BinaryOperator<Deque<A>> combiner() {
return (stack1, stack2) -> {
if (stack1.isEmpty()) return stack2;
if (stack2.isEmpty()) return stack1;
if (comp.compare(stack1.peekFirst(), stack2.peekFirst()) == 0) {
stack1.addAll(stack2);
}
return stack1;
};
}
#Override
public Function<Deque<A>, Deque<A>> finisher() {
return stack -> stack;
}
#Override
public Set<Characteristics> characteristics() {
return Set.of(Characteristics.UNORDERED);
}
}
Class A that I used for testing purposes
public class A {
private int val1;
private int val2;
public A(int val1, int val2) {
this.val1 = val1;
this.val2 = val2;
}
public int getVal1() {
return val1;
}
public int getVal2() {
return val2;
}
#Override
public String toString() {
return "A val1: " + val1 + " val2: " + val2;
}
}
OUTPUT
A val1: 5 val2: 8
A val1: 5 val2: 27

Thanks for posting the information I requested. Here is what I came up with.
Create a list of Course objects
List<Course> list = List.of(
new Course("a", 10, 5),
new Course("b", 20, 5),
new Course("c", 30, 0));
Stream the methods and apply them to the list
List<String> results = Stream.<Function<Course, Integer>>of(
Course::getCapacity,
Course::getStudents)
.map(fnc-> getMaxString(fnc, list))
.toList();
results.forEach(System.out::println);
print the results
c
a b
I wrote a simple method that takes a method reference and list and finds the maximum. It does not do any sorting.
allocate a list to hold the names
set the maximum to the lowest possible
iterate thru the list applying the method.
if the value is greater than the current max replace it and clear the current list of names.
otherwise, if equal, add a new name.
once done, return the formatted string.
static String getMaxString(Function<Course, Integer> fnc,
List<Course> list) {
List<String> result = new ArrayList<>();
int max = Integer.MIN_VALUE;
for (Course obj : list) {
int val = fnc.apply(obj);
if (val >= max) {
if (val > max) {
result.clear();
}
max = val;
result.add(obj.getName());
}
}
return String.join(" ", result);
}

Calculator for metric distance from an expression that contains different scales

public enum Operator {
PLUS("+"),
MINUS("-");
private final String operator;
Operator(String operator) {
this.operator = operator;
}
public String getOperator() {
return operator;
}
public static Operator getByValue(String operator) {
for (Operator operatorEnum : Operator.values()) {
if (operatorEnum.getOperator().equals(operator)) {
return operatorEnum;
}
}
throw new IllegalArgumentException("Invalid value");
}
}
//////////
public enum MetricConvertor {
m(1000),
cm(10),
mm(1),
km(1000000),
dm(100);
private int scale;
MetricConvertor(int scale) {
this.scale = scale;
}
public int getScale() {
return scale;
}
}
/////////
public class Application {
public static void main(String[] args) {
int scale = MetricConvertor.valueOf("m").getScale();
}
I wan to create a calculator that is capable of computing a metric distance value from an expression that contains different scales and systems.
Output should be specified by the user.
Only Addition and subtraction is allowed.
Output is in lowest unit.
Expression: 10 cm + 1 m - 10 mm
Result: 1090 mm
I am stuck at this point, how can I add or substract the values for a list and convert them at the lowest scale sistem( eg above mm, but it can be dm if are added for example dm + m + km)

Here is solution
split each string by add/minus and add it to appropriate list
split number and metric in each list(can use matcher) and sum it
result = sumAdd - sumMinus(mm).
Please optimize it, because i don't have time to optimize this code, I need to go to bed :D
Result is in mm, so you have to get lowest metric and recaculate it(leave it to you).
private static int caculator(String exp) {
List<String> addList = new ArrayList<>();
List<String> minusList = new ArrayList<>();
int checkPoint = 0;
boolean op = true;//default first value is plus
// Split string with add/minus
for (int i = 1; i < exp.length(); i++) {
String s = exp.substring(i, i + 1);
if (Operator.PLUS.getOperator().equals(s)) {
checkOperator(addList, minusList, op, exp.substring(checkPoint, i).trim());
checkPoint = i + 1;
op = true;
continue;
}
if (Operator.MINUS.getOperator().equals(s)) {
checkOperator(addList, minusList, op, exp.substring(checkPoint, i).trim());
checkPoint = i + 1;
op = false;
continue;
}
}
// Add last string
checkOperator(addList, minusList, op, exp.substring(checkPoint).trim());
// Get sum each list
int sumAdd = sumList(addList);
int sumMinus = sumList(minusList);
return sumAdd - sumMinus;
}
//sum a list
private static int sumList(List<String> addList) {
int sum = 0;
for (String s: addList) {
String[] arr = s.split(" ");
int value = Integer.parseInt(arr[0]);
int scale = MetricConvertor.valueOf(arr[1]).getScale();
sum += value * scale;
}
return sum;
}
// check operator to put into approriate list
private static void checkOperator(List<String> addList, List<String> minusList, boolean op, String substring) {
if (op) {
addList.add(substring);
} else {
minusList.add(substring);
}
}

Polynomial program not working as expected

So I Created a class Term. This class represents a term of a polynomial such as 2x4 where 2 is coefficient and 4 is exponent of the
term.
Data members:-
int coefficient
int exponent
public class Term2 {
private int coefficient;
private int exponent;
public Term2() {
coefficient = 0;
exponent = 0;
}
public Term2(int coefficient, int exponent) {
this.coefficient = coefficient;
this.exponent = exponent;
}
public int getCoefficient() {
return coefficient;
}
public void setCoefficient(int coefficient) {
this.coefficient = coefficient;
}
public int getExponent() {
return exponent;
}
public void setExponent(int exponent) {
this.exponent = exponent;
}
}
then I Created another class called Polynomial. The internal representation of a polynomial is an array of Terms. The size of this array should be fixed. I
Provided a constructor for this class that will set all terms of a polynomial object as zero (where coefficient is 0 and exponent is 0).
then I created a funtion called
setTerm(int, int)
which Setting a term of a polynomial object. Each successive call of
this function should set next term of the polynomial object.
package javaapplication2;
import java.util.Scanner;
public class Polynomials {
private Term2 terms[];
private int valueLength = 0;
public Polynomials(int termSize) {
terms = new Term2[termSize];
for (int i = 0; i < terms.length; i++) {
terms[i] = new Term2(0, 0);
}
}
public void setTerm(int c, int e) {
if (valueLength >= terms.length) {
System.out.println("big");
return;
}
terms[valueLength++] = new Term2(c, e);
if (e > 0) {
for (int i = 0; i < terms.length; i++) {
terms[i] = new Term2(c, e);
}
}
}
public static void main(String[] args) {
int n;
System.out.println("Enter the number of terms : ");
Scanner in = new Scanner(System.in);
n = in.nextInt();
Polynomials p = new Polynomials(n);
p.setTerm(2, 3);
Term2 t = new Term2();
}
}
STUCKED
is the code structure is correct as I am not able to get the expected output in addtion i also want to achieve the two below funtionality
1.sort() ñ to arrange the terms in ascending order of exponents.
Provide a function to print a polynomial object
please suggest me the best solution
OUTPUT
run:
Enter the number of terms :
2
BUILD SUCCESSFUL (total time: 3 seconds)

The arrray is a too complicated data structure here. (Besides if (e > 0) { ... } messes things up.)
Either a Map from exponent to Term2 or to the coefficient.
public class Polynomials {
private SortedMap<Integer, Term2> termsByExponent = new TreeMap<>();
public Polynomials() {
}
public void setTerm(int c, int e) {
termsByExponent.put(e, new Term2(c, e));
}
/**
* #param exp the exponent (not the index).
*/
public Term2 getTerm(int exp) {
return termsByExponent.computeIfAbsent(exp, e -> new Term2(0, e));
}
public Term2 getTermByIndex(int i) {
return termsByExponent.values().get(i);
}
public int size() {
return map.size();
}
#Override
public String toString() {
return termsByExponent.values().stream()
.map(t -> String.format("%s%d.x^%d",
t.getCoefficient() >= 0 ? "+" : "", // Minus already there.
t.getCoefficient(),
t.getExponent()))
.collect(Collectors.join(""))
.replaceFirst("\\.x\\^0\\b", "")
.replaceFirst("\\^1\\b", "");
}
}

Can't locate the problems in this simple Genetic Algorithm program

I have written a simple genetic algorithm program in java. What it is does is maximize the decimal value represented by the bits in the chromosome. Somehow mutation is not working as expected, e.g. causing two genes to mutate when just one is to change. The print statements I have included there show which to mutate, but in addition to that some more chromosomes get mutated. I can't figure out what the problem is :-(
Here are my java classes.
Gene.java
public class Gene {
private int value;
public Gene() {
value = Math.random() < 0.5 ? 0 : 1;
}
public Gene(int value) {
if (value != 0 && value != 1) {
throw new IllegalArgumentException("value must be either 0 or 1");
}
else {
this.value = value;
}
}
public void mutate() {
value = 1 - value;
}
public int value() {
return value;
}
#Override
public String toString() {
return String.valueOf(value);
}
}
Chromosome.java
import java.util.ArrayList;
import java.util.List;
public class Chromosome implements Comparable {
private ArrayList<Gene> genes;
private final int chromosomeLength;
public Chromosome(int length) {
this.genes = new ArrayList<>();
this.chromosomeLength = length > 0 ? length : 16;
for (int i = 0; i < chromosomeLength; i++) {
this.genes.add(i, new Gene());
}
}
public List<Gene> getAllele(int fromIndex, int toIndex) {
return new ArrayList<>(genes.subList(fromIndex, toIndex));
}
public void setAllele(int fromIndex, List<Gene> allele) {
int lastIndex = fromIndex + allele.size();
if (lastIndex > chromosomeLength) {
throw new IndexOutOfBoundsException("the allele exceeds beyond the size of the chromosome");
}
for (int i = fromIndex, j = 0; i < lastIndex; i++, j++) {
genes.set(i, allele.get(j));
}
}
public int getChromosomeLength() {
return chromosomeLength;
}
public void setGeneAt(int index, Gene gene) {
genes.set(index, gene);
}
public Gene getGeneAt(int index) {
return genes.get(index);
}
public int value() {
return Integer.parseInt(this.toString(), 2);
}
#Override
public String toString() {
StringBuilder chromosome = new StringBuilder("");
genes.stream().forEach((Gene g) -> chromosome.append(g));
return chromosome.toString();
}
#Override
public int compareTo(Object anotherChromosome) {
Chromosome c = (Chromosome) anotherChromosome;
return this.value() - c.value();
}
}
GenePool.java
import java.util.ArrayList;
import java.util.Arrays;
public class GenePool {
private final ArrayList<Chromosome> genePool;
private final int genePoolSize;
private final int chromosomeLength;
private final double crossOverRate;
private final double mutationRate;
private int[] crossPoints;
public GenePool(int numOfChromosome, int chromosomeLength, double crossOverRate, double mutationRate) {
this.genePoolSize = numOfChromosome;
this.chromosomeLength = chromosomeLength > 0 ? chromosomeLength : 16;
this.crossOverRate = crossOverRate;
this.mutationRate = mutationRate;
crossPoints = new int[1];
crossPoints[0] = this.chromosomeLength / 2;
genePool = new ArrayList<>();
for (int i = 0; i < numOfChromosome; i++) {
genePool.add(new Chromosome(chromosomeLength));
}
}
public int getGenePoolSize() {
return genePoolSize;
}
public Chromosome getChromosomeAt(int index) {
return genePool.get(index);
}
public void setChromosomeAt(int index, Chromosome c) {
genePool.set(index, c);
}
public int getChromosomeLength() {
return chromosomeLength;
}
public Chromosome[] crossOver(Chromosome c1, Chromosome c2) {
Chromosome[] offsprings = new Chromosome[2];
offsprings[0] = new Chromosome(c1.getChromosomeLength());
offsprings[1] = new Chromosome(c1.getChromosomeLength());
Chromosome[] parentChromosomes = {c1, c2};
int selector = 0;
for (int i = 0, start = 0; i <= crossPoints.length; i++) {
int crossPoint = i == crossPoints.length ? c1.getChromosomeLength() : crossPoints[i];
offsprings[0].setAllele(start, parentChromosomes[selector].getAllele(start, crossPoint));
offsprings[1].setAllele(start, parentChromosomes[1 - selector].getAllele(start, crossPoint));
selector = 1 - selector;
start = crossPoint;
}
return offsprings;
}
public void mutateGenePool() {
int totalGeneCount = genePoolSize * chromosomeLength;
System.out.println("Mutating genes:");
for (int i = 0; i < totalGeneCount; i++) {
double prob = Math.random();
if (prob < mutationRate) {
System.out.printf("Chromosome#: %d\tGene#: %d\n", i / chromosomeLength, i % chromosomeLength);
genePool.get(i / chromosomeLength).getGeneAt(i % chromosomeLength).mutate();
}
}
System.out.println("");
}
public int getLeastFitIndex() {
int index = 0;
int min = genePool.get(index).value();
int currentValue;
for (int i = 1; i < genePoolSize; i++) {
currentValue = genePool.get(i).value();
if (currentValue < min) {
index = i;
min = currentValue;
}
}
return index;
}
public void saveFittest(ArrayList<Chromosome> offsprings) {
// sort in ascending order
offsprings.sort(null);
offsprings.stream().forEach((offspring) -> {
int leastFitIndex = getLeastFitIndex();
if (offspring.value() > genePool.get(leastFitIndex).value()) {
genePool.set(leastFitIndex, offspring);
}
});
}
public void evolve(int noOfGeneration) {
for (int generation = 1; generation <= noOfGeneration; generation++) {
System.out.println("Generation :" + generation);
ArrayList<Integer> selection = new ArrayList<>();
for (int i = 0; i < genePoolSize; i++) {
if (Math.random() <= crossOverRate) {
selection.add(i);
}
}
if (selection.size() % 2 == 1) {
selection.remove(selection.size() - 1);
}
ArrayList<Chromosome> offsprings = new ArrayList<>();
for (int i = 0; i < selection.size(); i += 2) {
int index1 = selection.get(i);
int index2 = selection.get(i + 1);
offsprings.addAll(Arrays.asList(crossOver(genePool.get(index1), genePool.get(index2))));
}
System.out.println("Before saving the offsprings");
displayChromosomes(genePool, "GenePool");
displayChromosomes(offsprings, "Offsprings");
saveFittest(offsprings);
System.out.println("Before mutation:");
displayChromosomes(genePool, "GenePool");
mutateGenePool();
System.out.println("After mutation:");
displayChromosomes(genePool, "GenePool");
System.out.println("\n\n");
}
}
public void displayChromosomes(ArrayList<Chromosome> geneList, String name) {
System.out.println(name);
if (geneList.isEmpty()) {
System.out.println("Empty list");
}
geneList.stream().forEach((c) -> {
System.out.println(c + " -> " + c.value());
});
System.out.println("");
}
}
GADemo.java
public class GADemo {
public static void main(String[] args) {
GenePool gp = new GenePool(6, 8, 0.25, 0.01);
gp.evolve(10);
}
}
After evolving for a number of generations, the chromosomes all tend to become exactly the same, or very similar. And the problem is that that value is not the maximum for that many bits, and sometimes even a small value. For example, for 8 bits the values should (tend to) approach 255, but this doesn't do so in my code. Someone please provide a hint where/how to look for and solve the problem.

Focus on these lines and imagine the references. These are from setAllele()
for (int i = fromIndex, j = 0; i < lastIndex; i++, j++) {
genes.set(i, allele.get(j));
}
You are basically copying the reference from one onto the other. They are the same Gene so whatever mutation you do on those genes, will also affect even other Chromosomes.
You must produce a deep copy here.

Initially each chromosome has an own list of genes. But when you do the crossover operation you set gene objects from one chromosome into the gene list of other chromosome.
When you evolve the system, the number of shared genes will rise and therefore ultimately all chromosomes will share the same genes. No matter how you mutate a gene the chromosomes are not affected.
EDIT:
As Incognito also answered the setAllele method seems to be the culprit where gene sharing starts. You may want to introduce a method in the gene class where you can set its value given another gene.

Duplicate values in a hashSet

I am trying to count the number of combinations of 1, 5, 10 and 25 that sum to n. Given that I don't want any repetitions (like 1+5 = 6 and 5+1 = 6). I am using a hashSet. I implemented a class named ResultSet that saves the number of 1, 5, 10, and 25 in a solution and I overrode the equals method. However, for some reason, my solution hashSet keeps returning duplicate values. Why?
import java.util.HashSet;
public class Solution {
public static void main(String[] args) {
int N = 6;
int combinationsSolution = new Combine(N).getSolution();
System.out.println("N= " + N + " Number of solutions= " + combinationsSolution);
}
}
class Combine {
private int solution;
private int n;
private HashSet<ResultSet> cacheUnordered = new HashSet<ResultSet>();
public Combine(int N) {
this.n = N;
this.solution = solve(n);
}
public int getSolution() {
return solution;
}
public int solve(int N) {
solve(N, 0, 0, 0, 0);
for (ResultSet r:cacheUnordered){
System.out.println(r.toString());
}
return cacheUnordered.size();
}
public void solve(int N, int substracted1, int substracted5, int substracted10, int substracted25) {
if (N == 0) {
cacheUnordered.add(new ResultSet(substracted1, substracted5, substracted10, substracted25));
} else if (N > 0) {
solve(N - 1, substracted1 + 1, substracted5, substracted10, substracted25);
solve(N - 5, substracted1, substracted5 + 1, substracted10, substracted25);
solve(N - 10, substracted1, substracted5, substracted10 + 1, substracted25);
solve(N - 25, substracted1, substracted5, substracted10, substracted25 + 1);
}
}
}
class ResultSet {
private int numberOf1;
private int numberOf5;
private int numberOf10;
private int numberOf25;
public ResultSet(int num1, int num5, int num10, int num25) {
numberOf1 = num1;
numberOf5 = num5;
numberOf10 = num10;
numberOf25 = num25;
}
#Override
public String toString(){
String result;
result = numberOf1 + " " + numberOf5 + " " + numberOf10 + " " + numberOf25;
return result;
}
#Override
public boolean equals(Object r2) {
if (r2 == null) {
return false;
}
if (!(r2 instanceof ResultSet)) {
return false;
}
ResultSet rr = (ResultSet) r2;
if (rr.numberOf1 == this.numberOf1 && rr.numberOf5 == this.numberOf5
&& rr.numberOf10 == this.numberOf10 && rr.numberOf25 == this.numberOf25) {
System.out.println("Comparing " + this.toString() + " to " + rr.toString());
return true;
} else {
return false;
}
}
public int getNum1() {
return numberOf1;
}
public int getNum5() {
return numberOf5;
}
public int getNum10() {
return numberOf10;
}
public int getNum25() {
return numberOf25;
}
}

For your ResultSet class, you defined an equals() method but not a hashCode() method. You need both methods for HashSet to work correctly. Please see this explanation. (It talks about HashMap, but it also applies to HashSet.)

As JavaDoc Clearly Specified
Note that it is generally necessary to override the hashCode method
whenever this method is overridden, so as to maintain the general
contract for the hashCode method, which states that equal objects must
have equal hash codes.
and you have not followed it , that is why you get duplicates ,
Please Read How HashCode and Equals Work it will help you out to understand the above statement better