BAEL-2253 - Difference Between @NotNull, @NotEmpty and @NotBlank Constraints in Bean Validation (#5310)

* Initial Commit

* Update UserNotBlankUnitTest.java

* Update UserNotEmptyUnitTest.java

* Update UserNotNullUnitTest.java

javaxval/pom.xml

@@ -1,55 +1,73 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-    <modelVersion>4.0.0</modelVersion>
-    <groupId>com.baeldung</groupId>
-    <artifactId>javaxval</artifactId>
-    <version>0.1-SNAPSHOT</version>
-
-    <parent>
-        <groupId>com.baeldung</groupId>
-        <artifactId>parent-modules</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
-    </parent>
-
-    <dependencies>
-        <dependency>
-            <groupId>org.hibernate</groupId>
-            <artifactId>hibernate-validator</artifactId>
-            <version>${hibernate-validator.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.hibernate</groupId>
-            <artifactId>hibernate-validator-annotation-processor</artifactId>
-            <version>${hibernate-validator.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>javax.el</groupId>
-            <artifactId>javax.el-api</artifactId>
-            <version>${javax.el-api.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.glassfish.web</groupId>
-            <artifactId>javax.el</artifactId>
-            <version>${javax.el.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.springframework</groupId>
-            <artifactId>spring-context</artifactId>
-            <version>${org.springframework.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.springframework</groupId>
-            <artifactId>spring-test</artifactId>
-            <version>${org.springframework.version}</version>
-        </dependency>
-    </dependencies>
-
-    <properties>
-        <validation-api.version>2.0.1.Final</validation-api.version>
-        <hibernate-validator.version>6.0.7.Final</hibernate-validator.version>
-        <javax.el-api.version>3.0.0</javax.el-api.version>
-        <javax.el.version>2.2.6</javax.el.version>
-        <org.springframework.version>5.0.2.RELEASE</org.springframework.version>
-    </properties>
-
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>javaxval</artifactId>
+    <version>0.1-SNAPSHOT</version>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>javax.validation</groupId>
+            <artifactId>validation-api</artifactId>
+            <version>${validation-api.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.hibernate</groupId>
+            <artifactId>hibernate-validator</artifactId>
+            <version>${hibernate-validator.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.hibernate</groupId>
+            <artifactId>hibernate-validator-annotation-processor</artifactId>
+            <version>${hibernate-validator.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.el</groupId>
+            <artifactId>javax.el-api</artifactId>
+            <version>${javax.el-api.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.glassfish.web</groupId>
+            <artifactId>javax.el</artifactId>
+            <version>${javax.el.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-context</artifactId>
+            <version>${org.springframework.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-test</artifactId>
+            <version>${org.springframework.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+    	
+    <properties>
+        <validation-api.version>2.0.1.Final</validation-api.version>
+        <hibernate-validator.version>6.0.7.Final</hibernate-validator.version>
+        <javax.el-api.version>3.0.0</javax.el-api.version>
+        <javax.el.version>2.2.6</javax.el.version>    
+        <org.springframework.version>5.0.2.RELEASE</org.springframework.version>
+        <junit.version>4.12</junit.version>
+        <assertj.version>3.11.1</assertj.version>
+    </properties>    
 </project>

javaxval/src/main/java/org/baeldung/javabeanconstraints/appplication/Application.java

@@ -0,0 +1,14 @@
+package org.baeldung.javabeanconstraints.appplication;
+
+import javax.validation.Validation;
+import javax.validation.Validator;
+import org.baeldung.javabeanconstraints.entities.UserNotBlank;
+
+public class Application {
+
+    public static void main(String[] args) throws Exception {
+        Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
+        UserNotBlank user = new UserNotBlank(" ");
+        validator.validate(user).stream().forEach(violation -> System.out.println(violation.getMessage())); 
+    }
+}

javaxval/src/main/java/org/baeldung/javabeanconstraints/entities/UserNotBlank.java

@@ -0,0 +1,22 @@
+package org.baeldung.javabeanconstraints.entities;
+
+import javax.validation.constraints.NotBlank;
+
+public class UserNotBlank {
+
+    @NotBlank(message = "Name is mandatory")
+    private final String name;
+    
+    public UserNotBlank(String name) {
+        this.name = name;
+    }
+    
+    public String getName() {
+        return name;
+    }
+    
+    @Override
+    public String toString() {
+        return "User{" + "name=" + name + "}";
+    }
+}

javaxval/src/main/java/org/baeldung/javabeanconstraints/entities/UserNotEmpty.java

@@ -0,0 +1,22 @@
+package org.baeldung.javabeanconstraints.entities;
+
+import javax.validation.constraints.NotEmpty;
+
+public class UserNotEmpty {
+    
+    @NotEmpty(message = "Name is mandatory")
+    private final String name;
+    
+    public UserNotEmpty(String name) {
+        this.name = name;
+    }
+    
+    public String getName() {
+        return name;
+    }
+    
+    @Override
+    public String toString() {
+        return "User{" + "name=" + name + "}";
+    }
+}

javaxval/src/main/java/org/baeldung/javabeanconstraints/entities/UserNotNull.java

@@ -0,0 +1,22 @@
+package org.baeldung.javabeanconstraints.entities;
+
+import javax.validation.constraints.NotNull;
+
+public class UserNotNull {
+    
+    @NotNull(message = "Name is mandatory")
+    private final String name;
+    
+    public UserNotNull(String name) {
+        this.name = name;
+    }
+    
+    public String getName() {
+        return name;
+    }
+    
+    @Override
+    public String toString() {
+        return "User{" + "name=" + name + "}";
+    }
+}

javaxval/src/test/java/org/baeldung/javabeanconstraints/test/UserNotBlankUnitTest.java

@@ -0,0 +1,63 @@
+package org.baeldung.javabeanconstraints.test;
+
+import java.util.Set;
+import javax.validation.ConstraintViolation;
+import javax.validation.Validation;
+import javax.validation.Validator;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.baeldung.javabeanconstraints.entities.UserNotBlank;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class UserNotBlankUnitTest {
+    
+    private static Validator validator;
+
+    @BeforeClass
+    public static void setupValidatorInstance() {
+        validator = Validation.buildDefaultValidatorFactory().getValidator();
+    }
+    
+    @Test
+    public void whenNotBlankName_thenNoConstraintViolations() {
+        UserNotBlank user = new UserNotBlank("John");
+        
+        Set<ConstraintViolation<UserNotBlank>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(0);
+    }
+    
+    @Test
+    public void whenBlankName_thenOneConstraintViolation() {
+        UserNotBlank user = new UserNotBlank(" ");
+        
+        Set<ConstraintViolation<UserNotBlank>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(1);
+    }
+    
+    @Test
+    public void whenEmptyName_thenOneConstraintViolation() {
+        UserNotBlank user = new UserNotBlank("");
+        
+        Set<ConstraintViolation<UserNotBlank>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(1);
+    }
+    
+    @Test
+    public void whenNullName_thenOneConstraintViolation() {
+        UserNotBlank user = new UserNotBlank(null);
+        
+        Set<ConstraintViolation<UserNotBlank>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(1);
+    }
+    
+    @Test
+    public void whenToString_thenCorrect() {
+        UserNotBlank user = new UserNotBlank("John");
+        
+        assertThat(user.toString()).isEqualTo("User{name=John}");
+    }
+}

javaxval/src/test/java/org/baeldung/javabeanconstraints/test/UserNotEmptyUnitTest.java

@@ -0,0 +1,54 @@
+package org.baeldung.javabeanconstraints.test;
+
+import java.util.Set;
+import javax.validation.ConstraintViolation;
+import javax.validation.Validation;
+import javax.validation.Validator;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.baeldung.javabeanconstraints.entities.UserNotEmpty;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class UserNotEmptyUnitTest {
+    
+    private static Validator validator;
+
+    @BeforeClass
+    public static void setupValidatorInstance() {
+        validator = Validation.buildDefaultValidatorFactory().getValidator();
+    }
+    
+    @Test
+    public void whenNotEmptyName_thenNoConstraintViolations() {
+        UserNotEmpty user = new UserNotEmpty("John");
+        
+        Set<ConstraintViolation<UserNotEmpty>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(0);
+    }
+    
+    @Test
+    public void whenEmptyName_thenOneConstraintViolation() {
+        UserNotEmpty user = new UserNotEmpty("");
+        
+        Set<ConstraintViolation<UserNotEmpty>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(1);
+    }
+    
+    @Test
+    public void whenNullName_thenOneConstraintViolation() {
+        UserNotEmpty user = new UserNotEmpty(null);
+        
+        Set<ConstraintViolation<UserNotEmpty>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(1);
+    }
+    
+    @Test
+    public void whenToString_thenCorrect() {
+        UserNotEmpty user = new UserNotEmpty("John");
+        
+        assertThat(user.toString()).isEqualTo("User{name=John}");
+    }
+}

javaxval/src/test/java/org/baeldung/javabeanconstraints/test/UserNotNullUnitTest.java

@@ -0,0 +1,54 @@
+package org.baeldung.javabeanconstraints.test;
+
+import java.util.Set;
+import javax.validation.ConstraintViolation;
+import javax.validation.Validation;
+import javax.validation.Validator;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.baeldung.javabeanconstraints.entities.UserNotNull;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class UserNotNullUnitTest {
+
+    private static Validator validator;
+
+    @BeforeClass
+    public static void setupValidatorInstance() {
+        validator = Validation.buildDefaultValidatorFactory().getValidator();
+    }
+
+    @Test
+    public void whenNotNullName_thenNoConstraintViolations() {
+        UserNotNull user = new UserNotNull("John");
+        
+        Set<ConstraintViolation<UserNotNull>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(0);
+    }
+    
+    @Test
+    public void whenNullName_thenOneConstraintViolation() {
+        UserNotNull user = new UserNotNull(null);
+        
+        Set<ConstraintViolation<UserNotNull>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(1);
+    }
+    
+    @Test
+    public void whenEmptyName_thenNoConstraintViolations() {
+        UserNotNull user = new UserNotNull("");
+        
+        Set<ConstraintViolation<UserNotNull>> violations = validator.validate(user);
+        
+        assertThat(violations.size()).isEqualTo(0);
+    }
+    
+    @Test
+    public void whenToString_thenCorrect() {
+        UserNotNull user = new UserNotNull("John");
+        
+        assertThat(user.toString()).isEqualTo("User{name=John}");
+    }
+}