Custom Constructors in Records (#13515)

core-java-modules/core-java-14/src/main/java/com/baeldung/java14/recordsCustomConstructors/StudentClassic.java

@@ -0,0 +1,61 @@
+package org.example;
+
+import java.util.Objects;
+
+public class StudentClassic {
+    private String name;
+    private int rollNo;
+    private int marks;
+
+    public StudentClassic(String name, int rollNo, int marks) {
+        this.name = name;
+        this.rollNo = rollNo;
+        this.marks = marks;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getRollNo() {
+        return rollNo;
+    }
+
+    public int getMarks() {
+        return marks;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public void setRollNo(int rollNo) {
+        this.rollNo = rollNo;
+    }
+
+    public void setMarks(int marks) {
+        this.marks = marks;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        StudentClassic that = (StudentClassic) o;
+        return rollNo == that.rollNo && marks == that.marks && Objects.equals(name, that.name);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, rollNo, marks);
+    }
+
+    @Override
+    public String toString() {
+        return "StudentClassic{" +
+                "name='" + name + '\'' +
+                ", rollNo=" + rollNo +
+                ", marks=" + marks +
+                '}';
+    }
+}

core-java-modules/core-java-14/src/main/java/com/baeldung/java14/recordsCustomConstructors/StudentRecord.java

@@ -0,0 +1,19 @@
+package org.example;
+
+import java.util.Comparator;
+import java.util.List;
+
+public record StudentRecord(String name, int rollNo, int marks) {
+    public StudentRecord(String name){
+        this(name, 0,0);
+    }
+    public StudentRecord {
+        if (marks < 0 || marks > 100) {
+            throw new IllegalArgumentException("Marks should be between 0 and 100.");
+        }
+        if (name == null) {
+            throw new IllegalArgumentException("Name cannot be null");
+        }
+    }
+}
+

core-java-modules/core-java-14/src/main/java/com/baeldung/java14/recordsCustomConstructors/StudentRecordV2.java

@@ -0,0 +1,22 @@
+package org.example;
+
+record StudentRecordV2(String name, int rollNo, int marks, char grade) {
+    public StudentRecordV2(String name, int rollNo, int marks) {
+        this(name, rollNo, marks, calculateGrade(marks));
+    }
+
+    private static char calculateGrade(int marks) {
+        if (marks >= 90) {
+            return 'A';
+        } else if (marks >= 80) {
+            return 'B';
+        } else if (marks >= 70) {
+            return 'C';
+        } else if (marks >= 60) {
+            return 'D';
+        } else {
+            return 'F';
+        }
+    }
+}
+

core-java-modules/core-java-14/src/main/java/com/baeldung/java14/recordsCustomConstructors/StudentRecordV3.java

@@ -0,0 +1,11 @@
+package org.example;
+
+import java.util.UUID;
+
+record StudentRecordV3(String name, int rollNo, int marks, String id) {
+
+    public StudentRecordV3(String name, int rollNo, int marks) {
+        this(name, rollNo, marks, UUID.randomUUID().toString());
+    }
+}
+

core-java-modules/core-java-14/src/test/java/com/baeldung/java14/recordsCustomConstructors/StudentRecordJUnitTest.java

@@ -0,0 +1,37 @@
+import org.example.StudentRecord;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+public class StudentRecordJUnitTest {
+
+    @Test
+    public void givenStudentRecordData_whenCreated_thenStudentPropertiesMatch() {
+        StudentRecord s1 = new StudentRecord("John", 1, 90);
+        StudentRecord s2 = new StudentRecord("Jane", 2, 80);
+        assertEquals("John", s1.name());
+        assertEquals(1, s1.rollNo());
+        assertEquals(90, s1.marks());
+        assertEquals("Jane", s2.name());
+        assertEquals(2, s2.rollNo());
+        assertEquals(80, s2.marks());
+    }
+    @Test
+    public void givenStudentRecordsList_whenSortingDataWithName_thenStudentsSorted(){
+        List<StudentRecord> studentRecords = List.of(
+                new StudentRecord("Dana", 1, 85),
+                new StudentRecord("Jim", 2, 90),
+                new StudentRecord("Jane", 3, 80)
+        );
+
+        List<StudentRecord> mutableStudentRecords = new ArrayList<>(studentRecords);
+        mutableStudentRecords.sort(Comparator.comparing(StudentRecord::name));
+
+        List<StudentRecord> sortedStudentRecords = List.copyOf(mutableStudentRecords);
+        assertEquals("Jane", sortedStudentRecords.get(1).name());
+    }
+}