KTLN-798 - Equals and hashcode generator in Kotlin (#766)

Author: abh1navv

core-kotlin-modules/core-kotlin-lang-4/src/main/java/com/baeldung/equalsandhashcode/Person.kt

@@ -0,0 +1,5 @@
+package com.baeldung.equalsandhashcode
+
+
+data class Person(val name: String, val age: Int, val address: String) {
+}

core-kotlin-modules/core-kotlin-lang-4/src/main/java/com/baeldung/equalsandhashcode/PersonWithUniqueName.kt

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+package com.baeldung.equalsandhashcode
+
+import java.util.Objects
+data class PersonWithUniqueName(val name: String, val age: Int, val address: String) {
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || javaClass != other.javaClass) return false
+        val otherPerson: PersonWithUniqueName = other as PersonWithUniqueName
+        return otherPerson.name == name
+    }
+
+    override fun hashCode(): Int {
+        return Objects.hash(name)
+    }
+}

core-kotlin-modules/core-kotlin-lang-4/src/main/java/com/baeldung/equalsandhashcode/PersonWithUniqueNameAndAge.kt

@@ -0,0 +1,5 @@
+package com.baeldung.equalsandhashcode
+
+data class PersonWithUniqueNameAndAge(val name: String, val age: Int) {
+    lateinit var address: String
+}

core-kotlin-modules/core-kotlin-lang-4/src/test/kotlin/com/baeldung/equalsandhashcode/PersonUnitTest.kt

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+package com.baeldung.equalsandhashcode
+
+import org.junit.jupiter.api.Test
+
+import org.junit.jupiter.api.Assertions.*
+
+class PersonUnitTest {
+
+    @Test
+    fun `equal when fields are equal`() {
+        val person1 = Person("John", 18, "Address")
+        val person2 = Person("John", 18, "Address")
+        assertEquals(person1, person2)
+    }
+
+    @Test
+    fun `not equal when fields are different`() {
+        val person1 = Person("John", 18, "Address")
+        val person2 = Person("John", 18, "Another Address")
+        assertNotEquals(person1, person2)
+    }
+}

core-kotlin-modules/core-kotlin-lang-4/src/test/kotlin/com/baeldung/equalsandhashcode/PersonWithUniqueNameAndAgeUnitTest.kt

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+package com.baeldung.equalsandhashcode
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+
+class PersonWithUniqueNameAndAgeUnitTest {
+    @Test
+    fun `equal when name and age fields are equal`() {
+        val person1 = PersonWithUniqueNameAndAge("John", 18)
+        person1.address = "Address"
+        val person2 = PersonWithUniqueNameAndAge("John", 18)
+        person2.address = "Another Address"
+
+        assertEquals(person1, person2)
+    }
+
+    @Test
+    fun `not equal when name and age fields are not equal`() {
+        val person1 = PersonWithUniqueNameAndAge("John", 18)
+        person1.address = "Address"
+        val person2 = PersonWithUniqueNameAndAge("John", 19)
+        person2.address = "Address"
+
+        assertNotEquals(person1, person2)
+    }
+}

core-kotlin-modules/core-kotlin-lang-4/src/test/kotlin/com/baeldung/equalsandhashcode/PersonWithUniqueNameUnitTest.kt

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+package com.baeldung.equalsandhashcode
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+
+class PersonWithUniqueNameUnitTest {
+    @Test
+    fun `equal when name field is equal`() {
+        val person1 = PersonWithUniqueName("John", 18, "Address")
+        val person2 = PersonWithUniqueName("John", 19, "Another Address")
+        assertEquals(person1, person2)
+    }
+}