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feat(random): generate students using streams

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- generate students with IntStream
- collect generated students into MyList using MyListCollector
- round average grade to two decimal places
- extract student generation into a separate method
This commit is contained in:
Володин Герман
2026-09-01 23:35:52 +04:00
parent 7d1e36917d
commit 6e7040b245
1 changed files with 126 additions and 63 deletions
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app/src/main/java/ru/project/random/RandomStudentGenerator.java
+126 -63
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@@ -1,53 +1,63 @@
package ru.project.random;
import ru.project.collection.MyLinkedList;
import ru.project.collection.MyList;
import ru.project.student.Student;
import java.util.Random;
import java.util.regex.Pattern;
import java.util.stream.IntStream;
import ru.project.collection.MyList;
import ru.project.collectors.MyCollectors;
import ru.project.student.Student;
import ru.project.student.StudentBuilder;
public class RandomStudentGenerator
{
private static final Random RANDOM = new Random();
private String minGroupNumber;
private String maxGroupNumber;
private Double minAverageGrade;
private Double maxAverageGrade;
private Integer minRecordBookNumber;
private Integer maxRecordBookNumber;
private static final double DEFAULT_MIN_GRADE = 0.0;
private static final double DEFAULT_MAX_GRADE = 5.0;
private static final int DEFAULT_MIN_RECORD_BOOK = 1;
private static final String GROUP_PATTERN_REGEX = "^[A-Z][0-9]{2}$";
private static final Pattern GROUP_PATTERN = Pattern.compile(GROUP_PATTERN_REGEX);
public RandomStudentGenerator setMinGroupNumber(String minGroupNumber) {
if (minGroupNumber != null && !GROUP_PATTERN.matcher(minGroupNumber).matches()) {
throw new IllegalArgumentException("minGroupNumber does not match Student group pattern: " + GROUP_PATTERN_REGEX);
}
this.minGroupNumber = minGroupNumber;
return this;
}
public RandomStudentGenerator setMaxGroupNumber(String maxGroupNumber) {
if (maxGroupNumber != null && !GROUP_PATTERN.matcher(maxGroupNumber).matches()) {
throw new IllegalArgumentException("maxGroupNumber does not match Student group pattern: " + GROUP_PATTERN_REGEX);
}
this.maxGroupNumber = maxGroupNumber;
return this;
public class RandomStudentGenerator {
private static final Random RANDOM = new Random();
private String minGroupNumber;
private String maxGroupNumber;
private Double minAverageGrade;
private Double maxAverageGrade;
private Integer minRecordBookNumber;
private Integer maxRecordBookNumber;
private static final double DEFAULT_MIN_GRADE = 0.0;
private static final double DEFAULT_MAX_GRADE = 5.0;
private static final int DEFAULT_MIN_RECORD_BOOK = 1;
private static final String GROUP_PATTERN_REGEX = "^[A-Z][0-9]{2}$";
private static final Pattern GROUP_PATTERN = Pattern.compile(GROUP_PATTERN_REGEX);
public RandomStudentGenerator setMinGroupNumber(String minGroupNumber) {
if (minGroupNumber != null && !GROUP_PATTERN.matcher(minGroupNumber).matches()) {
throw new IllegalArgumentException(
"minGroupNumber does not match Student group pattern: " + GROUP_PATTERN_REGEX);
}
this.minGroupNumber = minGroupNumber;
return this;
}
public RandomStudentGenerator setMaxGroupNumber(String maxGroupNumber) {
if (maxGroupNumber != null && !GROUP_PATTERN.matcher(maxGroupNumber).matches()) {
throw new IllegalArgumentException(
"maxGroupNumber does not match Student group pattern: " + GROUP_PATTERN_REGEX);
}
this.maxGroupNumber = maxGroupNumber;
return this;
}
public RandomStudentGenerator setMinAverageGrade(double minAverageGrade) {
if (minAverageGrade < DEFAULT_MIN_GRADE || minAverageGrade > DEFAULT_MAX_GRADE) {
throw new IllegalArgumentException(
"minAverageGrade out of Student allowed range ["
+ DEFAULT_MIN_GRADE
@@ -55,12 +65,16 @@ public class RandomStudentGenerator
+ DEFAULT_MAX_GRADE
+ "]");
}
this.minAverageGrade = minAverageGrade;
return this;
}
public RandomStudentGenerator setMaxAverageGrade(double maxAverageGrade) {
if (maxAverageGrade < DEFAULT_MIN_GRADE || maxAverageGrade > DEFAULT_MAX_GRADE) {
throw new IllegalArgumentException(
"maxAverageGrade out of Student allowed range ["
+ DEFAULT_MIN_GRADE
@@ -68,25 +82,33 @@ public class RandomStudentGenerator
+ DEFAULT_MAX_GRADE
+ "]");
}
this.maxAverageGrade = maxAverageGrade;
return this;
}
public RandomStudentGenerator setMinRecordBookNumber(int minRecordBookNumber) {
if (minRecordBookNumber < DEFAULT_MIN_RECORD_BOOK) {
throw new IllegalArgumentException(
"minRecordBookNumber must be >= " + DEFAULT_MIN_RECORD_BOOK);
}
this.minRecordBookNumber = minRecordBookNumber;
return this;
}
public RandomStudentGenerator setMaxRecordBookNumber(int maxRecordBookNumber) {
if (maxRecordBookNumber < DEFAULT_MIN_RECORD_BOOK) {
throw new IllegalArgumentException(
"maxRecordBookNumber must be >= " + DEFAULT_MIN_RECORD_BOOK);
}
this.maxRecordBookNumber = maxRecordBookNumber;
return this;
}
@@ -94,75 +116,116 @@ public class RandomStudentGenerator
if (size < 0) {
throw new IllegalArgumentException("size must be non-negative");
}
validateRanges();
MyList<Student> result = new MyLinkedList<>();
for (int i = 0; i < size; i++) {
String group = generateGroupNumber();
double grade = generateAverageGrade();
int recordBook = generateRecordBookNumber();
Student student =
new StudentBuilder()
.setGroupNumber(group)
.setAverageGrade(grade)
.setRecordBookNumber(recordBook)
.build();
result.add(student);
}
return result;
return IntStream.range(0, size)
.mapToObj(i -> generateStudent())
.collect(MyCollectors.toMyList());
}
private double generateAverageGrade() {
double min = (minAverageGrade != null) ? minAverageGrade : DEFAULT_MIN_GRADE;
double max = (maxAverageGrade != null) ? maxAverageGrade : DEFAULT_MAX_GRADE;
double range = max - min;
double grade = min + (range * RANDOM.nextDouble());
return Math.round(grade * 100.0) / 100.0;
private Student generateStudent() {
String groupNumber = generateGroupNumber();
double averageGrade = generateAverageGrade();
int recordBookNumber = generateRecordBookNumber();
return new StudentBuilder()
.setGroupNumber(groupNumber)
.setAverageGrade(averageGrade)
.setRecordBookNumber(recordBookNumber)
.build();
}
private void validateRanges() {
double effectiveMinGrade = minAverageGrade != null ? minAverageGrade : DEFAULT_MIN_GRADE;
double effectiveMaxGrade = maxAverageGrade != null ? maxAverageGrade : DEFAULT_MAX_GRADE;
if (effectiveMinGrade > effectiveMaxGrade) {
throw new IllegalArgumentException("minAverageGrade cannot be greater than maxAverageGrade");
}
if (minGroupNumber != null && maxGroupNumber != null) {
if (minGroupNumber.compareTo(maxGroupNumber) > 0) {
throw new IllegalArgumentException("minGroupNumber cannot be greater than maxGroupNumber");
}
int effectiveMinRecord =
minRecordBookNumber != null ? minRecordBookNumber : DEFAULT_MIN_RECORD_BOOK;
int effectiveMaxRecord = maxRecordBookNumber != null ? maxRecordBookNumber : Integer.MAX_VALUE;
if (effectiveMaxRecord == Integer.MAX_VALUE) {
effectiveMaxRecord = effectiveMinRecord + 999_999;
}
if (effectiveMinRecord > effectiveMaxRecord) {
throw new IllegalArgumentException(
"minRecordBookNumber cannot be greater than maxRecordBookNumber");
}
if (minGroupNumber != null
&& maxGroupNumber != null
&& minGroupNumber.compareTo(maxGroupNumber) > 0) {
throw new IllegalArgumentException("minGroupNumber cannot be greater than maxGroupNumber");
}
}
private String generateGroupNumber() {
String min = (minGroupNumber != null) ? minGroupNumber : "A00";
String max = (maxGroupNumber != null) ? maxGroupNumber : "Z99";
String min = minGroupNumber != null ? minGroupNumber : "A00";
String max = maxGroupNumber != null ? maxGroupNumber : "Z99";
char minLetter = min.charAt(0);
char maxLetter = max.charAt(0);
int minDigit = Integer.parseInt(min.substring(1));
int maxDigit = Integer.parseInt(max.substring(1));
char letter = (char) (minLetter + RANDOM.nextInt((maxLetter - minLetter) + 1));
int digit;
if (letter == minLetter && letter == maxLetter) {
digit = minDigit + RANDOM.nextInt((maxDigit - minDigit) + 1);
} else if (letter == minLetter) {
digit = minDigit + RANDOM.nextInt(100 - minDigit);
} else if (letter == maxLetter) {
digit = RANDOM.nextInt(maxDigit + 1);
} else {
digit = RANDOM.nextInt(100);
}
return letter + String.format("%02d", digit);
}
private double generateAverageGrade() {
double min = (minAverageGrade != null) ? minAverageGrade : DEFAULT_MIN_GRADE;
double max = (maxAverageGrade != null) ? maxAverageGrade : DEFAULT_MAX_GRADE;
double min = minAverageGrade != null ? minAverageGrade : DEFAULT_MIN_GRADE;
double max = maxAverageGrade != null ? maxAverageGrade : DEFAULT_MAX_GRADE;
double range = max - min;
return min + (range * RANDOM.nextDouble());
double grade = min + (range * RANDOM.nextDouble());
return Math.round(grade * 100.0) / 100.0;
}
private int generateRecordBookNumber() {
int min = (minRecordBookNumber != null) ? minRecordBookNumber : DEFAULT_MIN_RECORD_BOOK;
int max =
(maxRecordBookNumber != null) ? maxRecordBookNumber : min + 999_999; // разумный максимум
int min = minRecordBookNumber != null ? minRecordBookNumber : DEFAULT_MIN_RECORD_BOOK;
int max = maxRecordBookNumber != null ? maxRecordBookNumber : min + 999_999;
if (max < min) {
max = min;
}
return min + RANDOM.nextInt((max - min) + 1);
}
}