feat(random): generate students using streams

- 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

app/src/main/java/ru/project/random/RandomStudentGenerator.java

@@ -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
+
-{
+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);
+
-        }
+      throw new IllegalArgumentException(
-        this.minGroupNumber = minGroupNumber;
+          "minGroupNumber does not match Student group pattern: " + GROUP_PATTERN_REGEX);
-        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;
     }
+
     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 =
+    return IntStream.range(0, size)
-          new StudentBuilder()
+        .mapToObj(i -> generateStudent())
-              .setGroupNumber(group)
+        .collect(MyCollectors.toMyList());
-              .setAverageGrade(grade)
+  }
-              .setRecordBookNumber(recordBook)
+
+  private Student generateStudent() {
+    String groupNumber = generateGroupNumber();
+
+    double averageGrade = generateAverageGrade();
+
+    int recordBookNumber = generateRecordBookNumber();
+
+    return new StudentBuilder()
+        .setGroupNumber(groupNumber)
+        .setAverageGrade(averageGrade)
+        .setRecordBookNumber(recordBookNumber)
         .build();
-
-      result.add(student);
-    }
-    return result;
   }
 
-    private double generateAverageGrade() {
+  private void validateRanges() {
-        double min = (minAverageGrade != null) ? minAverageGrade : DEFAULT_MIN_GRADE;
+    double effectiveMinGrade = minAverageGrade != null ? minAverageGrade : DEFAULT_MIN_GRADE;
-        double max = (maxAverageGrade != null) ? maxAverageGrade : DEFAULT_MAX_GRADE;
+
-        double range = max - min;
+    double effectiveMaxGrade = maxAverageGrade != null ? maxAverageGrade : DEFAULT_MAX_GRADE;
-        double grade = min + (range * RANDOM.nextDouble());
+
-        return Math.round(grade * 100.0) / 100.0;
+    if (effectiveMinGrade > effectiveMaxGrade) {
+      throw new IllegalArgumentException("minAverageGrade cannot be greater than maxAverageGrade");
     }
-    if (minGroupNumber != null && maxGroupNumber != null) {
+
-      if (minGroupNumber.compareTo(maxGroupNumber) > 0) {
+    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 min = minGroupNumber != null ? minGroupNumber : "A00";
-    String max = (maxGroupNumber != null) ? maxGroupNumber : "Z99";
+
+    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 min = minAverageGrade != null ? minAverageGrade : DEFAULT_MIN_GRADE;
-    double max = (maxAverageGrade != null) ? maxAverageGrade : DEFAULT_MAX_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 min = minRecordBookNumber != null ? minRecordBookNumber : DEFAULT_MIN_RECORD_BOOK;
-    int max =
+
-        (maxRecordBookNumber != null) ? maxRecordBookNumber : min + 999_999; // разумный максимум
+    int max = maxRecordBookNumber != null ? maxRecordBookNumber : min + 999_999;
+
     if (max < min) {
       max = min;
     }
+
     return min + RANDOM.nextInt((max - min) + 1);
   }
 }