Using contracts in Kotlin

jeorg-kotlin-coroutines/coroutines-crums-group-1/pom.xml

@@ -34,6 +34,14 @@
             <groupId>org.jetbrains.kotlinx</groupId>
             <artifactId>kotlinx-coroutines-core-jvm</artifactId>
         </dependency>
+        <dependency>
+            <groupId>jakarta.validation</groupId>
+            <artifactId>jakarta.validation-api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.hibernate</groupId>
+            <artifactId>hibernate-validator</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.jetbrains.kotlinx</groupId>
             <artifactId>kotlinx-coroutines-test</artifactId>

jeorg-kotlin-coroutines/coroutines-crums-group-1/src/main/kotlin/org/jesperancinha/ktd/DSLContractsSmartCasting.kt

@@ -0,0 +1,60 @@
+package org.jesperancinha.ktd
+
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
+
+class DSLContractsSmartCasting {
+    fun showContract(id: Long?): Long? {
+        if (isValidIDE(id)) {
+            doWithId(id)
+        }
+        return id
+    }
+
+    fun doWithId(id: Long): Long {
+        println("Made contract with id $id")
+        return id
+    }
+
+    @OptIn(ExperimentalContracts::class)
+    fun isValidIDE(id: Long?): Boolean {
+        contract { returns(true) implies (id != null) }
+        return id != null && id != 0L
+    }
+
+    companion object {
+        @JvmStatic
+        fun main(args: Array<String> = emptyArray()) {
+            println("${DSLContractsSmartCasting().showContract(123)}")
+            println("${DSLContractsSmartCasting().showContract(null)}")
+        }
+    }
+}
+class ContractsExtension {
+    fun showContract(id: Long?): Long? {
+        if (id.isValidID()) {
+            doWithId(id!!)
+        }
+        return id
+    }
+
+    fun doWithId(id: Long): Long {
+        println("Made contract with id $id")
+        return id
+    }
+
+    @OptIn(ExperimentalContracts::class)
+    fun Long?.isValidID(): Boolean {
+        contract { returns(true) implies (this@isValidID != null) }
+        return this != null && this != 0L
+    }
+
+    companion object {
+        @JvmStatic
+        fun main(args: Array<String> = emptyArray()) {
+            DSLContractsSmartCasting.main()
+            println("${DSLContractsSmartCasting().showContract(123)}")
+            println("${DSLContractsSmartCasting().showContract(null)}")
+        }
+    }
+}

jeorg-kotlin-coroutines/coroutines-crums-group-1/src/main/kotlin/org/jesperancinha/ktd/Main.kt

@@ -9,5 +9,8 @@ object Main {
         TrainStationManager.main()
         NeuralNetworksCancelling.main()
         StructuredConcurrency.main()
+        ValidationUsersEmail.main()
+        ContractsExtension.main()
+        org.jesperancinha.ktd.java.ValidationUsersEmail.main(emptyArray())
     }
 }

jeorg-kotlin-coroutines/coroutines-crums-group-1/src/main/kotlin/org/jesperancinha/ktd/ValidationUsersEmail.kt

@@ -0,0 +1,24 @@
+package org.jesperancinha.ktd
+
+import jakarta.validation.Validation
+import jakarta.validation.constraints.Email
+
+
+data class User (
+    @field:Email(message = "Please insert a valid email")
+    val email:String
+)
+
+class ValidationUsersEmail {
+  companion object {
+      @JvmStatic
+      fun main(args: Array<String> = emptyArray()) {
+          val factory = Validation.buildDefaultValidatorFactory()
+          val validator = factory.validator
+          val validate1 = validator.validate(User("bad"))
+          println(validate1)
+          val validate2 = validator.validate(User("user@someemail.com"))
+          println(validate2)
+      }
+  }
+}

jeorg-kotlin-coroutines/coroutines-crums-group-1/src/main/kotlin/org/jesperancinha/ktd/java/User.java

@@ -0,0 +1,21 @@
+package org.jesperancinha.ktd.java;
+
+import jakarta.validation.constraints.Email;
+
+    public class User {
+
+        @Email(message = "Please insert a valid email")
+        private String email;
+
+        public User(String email) {
+            this.email = email;
+        }
+
+        public String getEmail() {
+            return email;
+        }
+
+        public void setEmail(String email) {
+            this.email = email;
+        }
+    }

jeorg-kotlin-coroutines/coroutines-crums-group-1/src/main/kotlin/org/jesperancinha/ktd/java/ValidationUsersEmail.java

@@ -0,0 +1,15 @@
+package org.jesperancinha.ktd.java;
+
+import static jakarta.validation.Validation.buildDefaultValidatorFactory;
+
+    public class ValidationUsersEmail {
+        public static void main(String[] args) {
+            try(var factory = buildDefaultValidatorFactory()) {
+                var validator = factory.getValidator();
+                var validate1 = validator.validate(new User("bad"));
+                System.out.println(validate1);
+                var validate2 = validator.validate(new User("user@someemail.com"));
+                System.out.println(validate2);
+            }
+        }
+    }

jeorg-kotlin-masters/jeorg-kotlin-constructor/pom.xml

@@ -29,7 +29,6 @@
         <dependency>
             <groupId>org.hibernate.validator</groupId>
             <artifactId>hibernate-validator</artifactId>
-            <version>8.0.1.Final</version>
         </dependency>
         <!-- https://mvnrepository.com/artifact/org.glassfish/jakarta.el -->
         <dependency>

pom.xml

@@ -56,6 +56,7 @@
         <slf4j-log4j12.version>2.0.5</slf4j-log4j12.version>
         <kotlinx-coroutines-reactor.version>1.7.3</kotlinx-coroutines-reactor.version>
         <kotlin-reflect.version>1.9.22</kotlin-reflect.version>
+        <hibernate-validator.version>8.0.1.Final</hibernate-validator.version>
     </properties>
 
     <modules>
@@ -177,6 +178,11 @@
                 <artifactId>slf4j-log4j12</artifactId>
                 <version>${slf4j-log4j12.version}</version>
             </dependency>
+            <dependency>
+                <groupId>org.hibernate</groupId>
+                <artifactId>hibernate-validator</artifactId>
+                <version>${hibernate-validator.version}</version>
+            </dependency>
             <dependency>
                 <groupId>org.jetbrains.kotlin</groupId>
                 <artifactId>kotlin-test-junit</artifactId>