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Practice task #1409

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28a96fe
first solution
May 13, 2026
ad1d901
firstSolution
May 13, 2026
807e2c4
checkstyle fixes
May 13, 2026
7749fcc
after fixes
May 13, 2026
a47d389
override remove
May 13, 2026
671ceb8
empty line remove
May 13, 2026
b6fb94c
fixes equals, added method periodInUkrConvertedToYears in class Candi…
May 14, 2026
9fee0c3
changes nad fixes applied
May 14, 2026
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250 changes: 250 additions & 0 deletions config/checkstyle.xml
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@@ -0,0 +1,250 @@
<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
"-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
"https://checkstyle.org/dtds/configuration_1_3.dtd">

<!--
Checkstyle configuration that checks the Google coding conventions from Google Java Style
that can be found at https://google.github.io/styleguide/javaguide.html.

Checkstyle is very configurable. Be sure to read the documentation at
http://checkstyle.sf.net (or in your downloaded distribution).

To completely disable a check, just comment it out or delete it from the file.

Authors: Max Vetrenko, Ruslan Diachenko, Roman Ivanov.
-->

<module name="Checker">
<property name="charset" value="UTF-8"/>

<property name="severity" value="error"/>

<property name="fileExtensions" value="java, properties, xml"/>
<!-- Checks for whitespace -->
<!-- See http://checkstyle.sf.net/config_whitespace.html -->
<module name="FileTabCharacter">
<property name="eachLine" value="true"/>
</module>
<module name="NewlineAtEndOfFile">
<property name="fileExtensions" value="java, properties, xml"/>
</module>
<module name="LineLength">
<property name="max" value="100"/>
<property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
</module>
<module name="TreeWalker">
<module name="OuterTypeFilename"/>
<module name="IllegalTokenText">
<property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
<property name="format"
value="\\u00(09|0(a|A)|0(c|C)|0(d|D)|22|27|5(C|c))|\\(0(10|11|12|14|15|42|47)|134)"/>
<property name="message"
value="Consider using special escape sequence instead of octal value or Unicode escaped value."/>
</module>
<module name="AvoidEscapedUnicodeCharacters">
<property name="allowEscapesForControlCharacters" value="true"/>
<property name="allowByTailComment" value="true"/>
<property name="allowNonPrintableEscapes" value="true"/>
</module>
<module name="AvoidStarImport"/>
<module name="IllegalImport"/>
<module name="RedundantImport"/>
<module name="UnusedImports"/>
<module name="OneTopLevelClass"/>
<module name="NoLineWrap"/>
<module name="EmptyBlock">
<property name="option" value="TEXT"/>
<property name="tokens"
value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
</module>
<module name="NeedBraces"/>
<module name="LeftCurly"/>
<module name="RightCurly">
<property name="id" value="RightCurlySame"/>
<property name="tokens"
value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE,
LITERAL_DO"/>
</module>
<module name="RightCurly">
<property name="id" value="RightCurlyAlone"/>
<property name="option" value="alone"/>
<property name="tokens"
value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT,
INSTANCE_INIT"/>
</module>
<module name="WhitespaceAround">
<property name="allowEmptyConstructors" value="true"/>
<property name="allowEmptyLambdas" value="true"/>
<property name="allowEmptyMethods" value="true"/>
<property name="allowEmptyTypes" value="true"/>
<property name="allowEmptyLoops" value="true"/>
<message key="ws.notFollowed"
value="WhitespaceAround: ''{0}'' is not followed by whitespace. Empty blocks may only be represented as '{}' when not part of a multi-block statement (4.1.3)"/>
<message key="ws.notPreceded"
value="WhitespaceAround: ''{0}'' is not preceded with whitespace."/>
</module>
<module name="OneStatementPerLine"/>
<module name="MultipleVariableDeclarations"/>
<module name="ArrayTypeStyle"/>
<module name="MissingSwitchDefault"/>
<module name="FallThrough"/>
<module name="VisibilityModifier">
<property name="protectedAllowed" value="true"/>
</module>
<module name="UpperEll"/>
<module name="ModifierOrder"/>
<module name="EmptyLineSeparator">
<property name="allowNoEmptyLineBetweenFields" value="true"/>
<property name="allowMultipleEmptyLines" value="false"/>
<property name="allowMultipleEmptyLinesInsideClassMembers" value="false"/>
</module>
<module name="SeparatorWrap">
<property name="id" value="SeparatorWrapDot"/>
<property name="tokens" value="DOT"/>
<property name="option" value="nl"/>
</module>
<module name="SeparatorWrap">
<property name="id" value="SeparatorWrapComma"/>
<property name="tokens" value="COMMA"/>
<property name="option" value="EOL"/>
</module>
<module name="SeparatorWrap">
<!-- ELLIPSIS is EOL until https://github.com/google/styleguide/issues/258 -->
<property name="id" value="SeparatorWrapEllipsis"/>
<property name="tokens" value="ELLIPSIS"/>
<property name="option" value="EOL"/>
</module>
<module name="SeparatorWrap">
<!-- ARRAY_DECLARATOR is EOL until https://github.com/google/styleguide/issues/259 -->
<property name="id" value="SeparatorWrapArrayDeclarator"/>
<property name="tokens" value="ARRAY_DECLARATOR"/>
<property name="option" value="EOL"/>
</module>
<module name="SeparatorWrap">
<property name="id" value="SeparatorWrapMethodRef"/>
<property name="tokens" value="METHOD_REF"/>
<property name="option" value="nl"/>
</module>
<module name="PackageName">
<property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
<message key="name.invalidPattern"
value="Package name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="TypeName">
<message key="name.invalidPattern"
value="Type name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="MemberName">
<property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
<message key="name.invalidPattern"
value="Member name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="ParameterName">
<property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
<message key="name.invalidPattern"
value="Parameter name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="LambdaParameterName">
<property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
<message key="name.invalidPattern"
value="Lambda parameter name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="CatchParameterName">
<property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
<message key="name.invalidPattern"
value="Catch parameter name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="LocalVariableName">
<property name="tokens" value="VARIABLE_DEF"/>
<property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
<message key="name.invalidPattern"
value="Local variable name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="ClassTypeParameterName">
<property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
<message key="name.invalidPattern"
value="Class type name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="MethodTypeParameterName">
<property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
<message key="name.invalidPattern"
value="Method type name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="InterfaceTypeParameterName">
<property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
<message key="name.invalidPattern"
value="Interface type name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="NoFinalizer"/>
<module name="GenericWhitespace">
<message key="ws.followed"
value="GenericWhitespace ''{0}'' is followed by whitespace."/>
<message key="ws.preceded"
value="GenericWhitespace ''{0}'' is preceded with whitespace."/>
<message key="ws.illegalFollow"
value="GenericWhitespace ''{0}'' should followed by whitespace."/>
<message key="ws.notPreceded"
value="GenericWhitespace ''{0}'' is not preceded with whitespace."/>
</module>
<module name="Indentation">
<property name="basicOffset" value="4"/>
<property name="braceAdjustment" value="0"/>
<property name="caseIndent" value="4"/>
<property name="throwsIndent" value="8"/>
<property name="lineWrappingIndentation" value="8"/>
<property name="arrayInitIndent" value="4"/>
</module>
<module name="AbbreviationAsWordInName">
<property name="ignoreFinal" value="false"/>
<property name="allowedAbbreviationLength" value="1"/>
</module>
<module name="OverloadMethodsDeclarationOrder"/>
<module name="VariableDeclarationUsageDistance"/>
<module name="CustomImportOrder">
<property name="sortImportsInGroupAlphabetically" value="true"/>
<property name="separateLineBetweenGroups" value="true"/>
<property name="customImportOrderRules" value="STATIC###THIRD_PARTY_PACKAGE"/>
</module>
<module name="MethodParamPad"/>
<module name="NoWhitespaceBefore">
<property name="tokens"
value="COMMA, SEMI, POST_INC, POST_DEC, DOT, ELLIPSIS, METHOD_REF"/>
<property name="allowLineBreaks" value="true"/>
</module>
<module name="ParenPad"/>
<module name="OperatorWrap">
<property name="option" value="NL"/>
<property name="tokens"
value="BAND, BOR, BSR, BXOR, DIV, EQUAL, GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR,
LT, MINUS, MOD, NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR, METHOD_REF "/>
</module>
<module name="AnnotationLocation">
<property name="id" value="AnnotationLocationMostCases"/>
<property name="tokens"
value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF"/>
</module>
<module name="AnnotationLocation">
<property name="id" value="AnnotationLocationVariables"/>
<property name="tokens" value="VARIABLE_DEF"/>
<property name="allowSamelineMultipleAnnotations" value="true"/>
</module>
<module name="NonEmptyAtclauseDescription"/>
<module name="MethodName">
<property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9_]*$"/>
<message key="name.invalidPattern"
value="Method name ''{0}'' must match pattern ''{1}''."/>
</module>
<module name="SingleLineJavadoc">
<property name="ignoreInlineTags" value="false"/>
</module>
<module name="EmptyCatchBlock">
<property name="exceptionVariableName" value="expected"/>
</module>
<module name="CommentsIndentation"/>
<module name="DeclarationOrder"/>
<module name="SingleSpaceSeparator">
<property name="validateComments" value="true"/>
</module>
</module>
</module>
2 changes: 1 addition & 1 deletion pom.xml
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Expand Up @@ -40,7 +40,7 @@
</execution>
</executions>
<configuration>
<configLocation>${maven.checkstyle.plugin.configLocation}</configLocation>
<configLocation>config/checkstyle.xml</configLocation>
<consoleOutput>true</consoleOutput>
<failsOnError>true</failsOnError>
<linkXRef>false</linkXRef>
Expand Down
27 changes: 25 additions & 2 deletions src/main/java/practice/CandidateValidator.java
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@@ -1,5 +1,28 @@
package practice;

public class CandidateValidator {
//write your code here
import java.util.function.Predicate;
import model.Candidate;

public class CandidateValidator implements Predicate<Candidate> {
public static final int MIN_AGE = 35;
public static final String REQUIRED_NATIONALITY = "Ukrainian";
public static final int MIN_LIVE_PERIOD = 10;

private int getYearsInUkraine(Candidate candidate) {
String period = candidate.getPeriodsInUkr();
int years = Math.abs(
Integer.parseInt(period.split("-")[0])
- Integer.parseInt(period.split("-")[1])
);
return years;
}

@Override
public boolean test(Candidate candidate) {
return candidate.getAge() >= MIN_AGE
&& candidate.isAllowedToVote()
&& REQUIRED_NATIONALITY.equals(candidate.getNationality())
&& getYearsInUkraine(candidate) >= MIN_LIVE_PERIOD;
}

@mateacademy-ai-mentor mateacademy-ai-mentor May 13, 2026

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Checklist item #9 requires using constants for magic numbers/strings. The value 10 for years lived should be defined as a constant instead of hardcoded.

}

46 changes: 39 additions & 7 deletions src/main/java/practice/StreamPractice.java
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Original file line number Diff line number Diff line change
@@ -1,11 +1,15 @@
package practice;

import java.util.Collections;
import java.util.Arrays;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.stream.IntStream;
import model.Candidate;
import model.Cat;
import model.Person;

@mateacademy-ai-mentor mateacademy-ai-mentor May 13, 2026

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Static methods cannot be overridden. Remove the @OverRide annotation or convert to instance method if you intend to implement Predicate interface properly.

public class StreamPractice {

/**
* Given list of strings where each element contains 1+ numbers:
* input = {"5,30,100", "0,22,7", ...}
Expand All @@ -14,7 +18,14 @@ public class StreamPractice {
* "Can't get min value from list: < Here is our input 'numbers' >"
*/
public int findMinEvenNumber(List<String> numbers) {
return 0;
return numbers.stream()
.flatMap(s -> Arrays.stream(s.split(",")))
.map(String::trim)
.mapToInt(Integer::parseInt)
.filter(n -> n % 2 == 0)
.min()
.orElseThrow(() -> new RuntimeException(
"Can't get min value from list: " + numbers));
}

/**
Expand All @@ -23,7 +34,12 @@ public int findMinEvenNumber(List<String> numbers) {
* But before that subtract 1 from each element on an odd position (having the odd index).
*/
public Double getOddNumsAverage(List<Integer> numbers) {
return 0D;
return IntStream.range(0, numbers.size())
.map(i -> i % 2 == 1 ? numbers.get(i) - 1 : numbers.get(i))
.filter(n -> n % 2 != 0)
.average()
.orElseThrow(() -> new NoSuchElementException(
"No odd numbers in the list: " + numbers));
Comment on lines 36 to +42

@mateacademy-ai-mentor mateacademy-ai-mentor May 13, 2026

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Task 2 Logic Error (still not fixed): The requirement states 'subtract 1 from each element on an odd position (having the odd index)' before averaging odd numbers. Current code only filters for odd numbers but never subtracts 1 from elements at odd indices. You need to use an indexed stream, subtract 1 from elements at odd indices first, then filter and average the resulting odd numbers.

}

/**
Expand All @@ -35,7 +51,10 @@ public Double getOddNumsAverage(List<Integer> numbers) {
* Example: select men who can be recruited to army (from 18 to 27 years old inclusively).
*/
public List<Person> selectMenByAge(List<Person> peopleList, int fromAge, int toAge) {
return Collections.emptyList();
return peopleList.stream()
.filter(p -> p.getSex().equals(Person.Sex.MAN)
&& (p.getAge() >= fromAge && p.getAge() <= toAge))
.toList();
}

/**
Expand All @@ -50,7 +69,12 @@ public List<Person> selectMenByAge(List<Person> peopleList, int fromAge, int toA
*/
public List<Person> getWorkablePeople(int fromAge, int femaleToAge,
int maleToAge, List<Person> peopleList) {
return Collections.emptyList();
return peopleList.stream()
.filter(p -> (p.getSex() == Person.Sex.MAN

@mateacademy-ai-mentor mateacademy-ai-mentor May 13, 2026

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Compare Enum values using equals() instead of ==

&& (p.getAge() >= fromAge && p.getAge() <= maleToAge))
|| (p.getSex().equals(Person.Sex.WOMAN)
&& (p.getAge() >= fromAge && p.getAge() <= femaleToAge)))
Comment on lines +72 to +76

@mateacademy-ai-mentor mateacademy-ai-mentor May 13, 2026

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Checklist violation: Use equals() method instead of == operator for Enum comparison. Replace both Person.Sex.MAN and Person.Sex.WOMAN comparisons with .equals() method calls.

.toList();
}

/**
Expand All @@ -59,7 +83,11 @@ public List<Person> getWorkablePeople(int fromAge, int femaleToAge,
* return the names of all cats whose owners are women from `femaleAge` years old inclusively.
*/
public List<String> getCatsNames(List<Person> peopleList, int femaleAge) {
return Collections.emptyList();
return peopleList.stream()

@mateacademy-ai-mentor mateacademy-ai-mentor May 13, 2026

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Checklist violation: Use equals() method instead of == operator for Enum comparison. Replace p.getSex() == Person.Sex.WOMAN with p.getSex().equals(Person.Sex.WOMAN).

.filter(p -> p.getSex().equals(Person.Sex.WOMAN) && p.getAge() >= femaleAge)
.flatMap(p -> p.getCats().stream())
.map(Cat::getName)
.toList();
}

/**
Expand All @@ -75,6 +103,10 @@ public List<String> getCatsNames(List<Person> peopleList, int femaleAge) {
* parametrized with Candidate in CandidateValidator.
*/
public List<String> validateCandidates(List<Candidate> candidates) {
return Collections.emptyList();
return candidates.stream()
.filter(new CandidateValidator())
.map(Candidate::getName)
.sorted()
.toList();
}
}
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