Merge pull request #2208 from hmantri05/master

Moving Address into Customer

.gitignore

@@ -33,3 +33,11 @@ spring-openid/src/main/resources/application.properties
 spring-security-openid/src/main/resources/application.properties
 
 spring-all/*.log
+
+*.jar
+
+SpringDataInjectionDemo/.mvn/wrapper/maven-wrapper.properties
+
+spring-call-getters-using-reflection/.mvn/wrapper/maven-wrapper.properties
+
+spring-check-if-a-property-is-null/.mvn/wrapper/maven-wrapper.properties

SpringDataInjectionDemo/.gitignore

@@ -0,0 +1,24 @@
+target/
+!.mvn/wrapper/maven-wrapper.jar
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+nbproject/private/
+build/
+nbbuild/
+dist/
+nbdist/
+.nb-gradle/

SpringDataInjectionDemo/pom.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>baeldung</groupId>
+	<artifactId>springdatainjectiondemo</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<packaging>jar</packaging>
+
+	<name>SpringDataInjectionDemo</name>
+	<description>Spring Data Injection Demp</description>
+
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>1.5.3.RELEASE</version>
+		<relativePath /> <!-- lookup parent from repository -->
+	</parent>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+		
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+
+</project>

SpringDataInjectionDemo/src/main/java/com/baeldung/SpringDataInjectionDemoApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SpringDataInjectionDemoApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(SpringDataInjectionDemoApplication.class, args);
+	}
+}

SpringDataInjectionDemo/src/main/java/com/baeldung/didemo/controller/OrderController.java

@@ -0,0 +1,46 @@
+package com.baeldung.didemo.controller;
+
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.MediaType;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.baeldung.didemo.model.Order;
+import com.baeldung.didemo.service.CustomerServiceConstructorDI;
+import com.baeldung.didemo.service.CustomerServiceConstructorWithoutSpringDI;
+import com.baeldung.didemo.service.CustomerServiceFieldDI;
+import com.baeldung.didemo.service.CustomerServiceSetterDI;
+import com.baeldung.didemo.service.OrderService;
+
+@RestController
+@RequestMapping(value = "/orders")
+public class OrderController {
+
+    @Autowired
+    CustomerServiceConstructorDI constructorDI;
+
+    @Autowired
+    CustomerServiceFieldDI fieldDI;
+
+    @Autowired
+    CustomerServiceSetterDI setterDI;
+
+    @RequestMapping(method = RequestMethod.GET)
+    public List<Order> getOrdersFieldDI(@RequestParam(required = false) String dIMethod) {
+        if ("setter".equals(dIMethod)) {
+            return setterDI.getCustomerOrders(1l);
+        } else if ("constructor".equals(dIMethod)) {
+            return constructorDI.getCustomerOrders(1l);
+        } else if ("field".equals(dIMethod)) {
+            return fieldDI.getCustomerOrders(1l);
+        } else {
+            OrderService orderSvc = new OrderService();
+            CustomerServiceConstructorWithoutSpringDI customerSvc = new CustomerServiceConstructorWithoutSpringDI(orderSvc);
+            return customerSvc.getCustomerOrders(1l);
+        }
+    }
+}

SpringDataInjectionDemo/src/main/java/com/baeldung/didemo/model/Order.java

@@ -0,0 +1,26 @@
+package com.baeldung.didemo.model;
+
+public class Order {
+
+    private Integer id;
+    private String item;
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getItem() {
+        return item;
+    }
+
+    public void setItem(String item) {
+        this.item = item;
+    }
+
+    // other order properties..
+
+}

SpringDataInjectionDemo/src/main/java/com/baeldung/didemo/service/CustomerServiceConstructorDI.java

@@ -0,0 +1,25 @@
+package com.baeldung.didemo.service;
+
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import com.baeldung.didemo.model.Order;
+
+@Service
+public class CustomerServiceConstructorDI {
+
+    OrderService orderService;
+
+    @Autowired
+    public CustomerServiceConstructorDI(OrderService orderService) {
+        super();
+        this.orderService = orderService;
+    }
+
+    public List<Order> getCustomerOrders(Long customerId) {
+        return orderService.getOrdersForCustomer(customerId);
+    }
+
+}

SpringDataInjectionDemo/src/main/java/com/baeldung/didemo/service/CustomerServiceConstructorWithoutSpringDI.java

@@ -0,0 +1,20 @@
+package com.baeldung.didemo.service;
+
+import java.util.List;
+
+import com.baeldung.didemo.model.Order;
+
+public class CustomerServiceConstructorWithoutSpringDI {
+
+    OrderService orderService;
+
+    public CustomerServiceConstructorWithoutSpringDI(OrderService orderService) {
+        super();
+        this.orderService = orderService;
+    }
+
+    public List<Order> getCustomerOrders(Long customerId) {
+        return orderService.getOrdersForCustomer(customerId);
+    }
+
+}

SpringDataInjectionDemo/src/main/java/com/baeldung/didemo/service/CustomerServiceFieldDI.java

@@ -0,0 +1,19 @@
+package com.baeldung.didemo.service;
+
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import com.baeldung.didemo.model.Order;
+
+@Service
+public class CustomerServiceFieldDI {
+
+    @Autowired
+    OrderService orderService;
+    
+    public List<Order> getCustomerOrders(Long customerId) {
+        return orderService.getOrdersForCustomer(customerId);
+    }
+}

SpringDataInjectionDemo/src/main/java/com/baeldung/didemo/service/CustomerServiceSetterDI.java

@@ -0,0 +1,24 @@
+package com.baeldung.didemo.service;
+
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import com.baeldung.didemo.model.Order;
+
+@Service
+public class CustomerServiceSetterDI {
+
+    OrderService orderService;
+
+    public List<Order> getCustomerOrders(Long customerId) {
+        return orderService.getOrdersForCustomer(customerId);
+    }
+
+    @Autowired
+    public void setOrderService(OrderService orderService) {
+        this.orderService = orderService;
+    }
+
+}

SpringDataInjectionDemo/src/main/java/com/baeldung/didemo/service/OrderService.java

@@ -0,0 +1,30 @@
+package com.baeldung.didemo.service;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.stereotype.Service;
+
+import com.baeldung.didemo.model.Order;
+
+@Service
+public class OrderService {
+
+    public List<Order> getOrdersForCustomer(Long id) {
+        List<Order> orders = new ArrayList<Order>();
+        
+        Order order1 = new Order();
+        order1.setId(1);
+        order1.setItem("Pizza");
+        
+        Order order2 = new Order();
+        order2.setId(1);
+        order2.setItem("Garlic Bread");
+        
+        orders.add(order1);
+        orders.add(order2);
+        
+        return orders;
+    }
+    
+}

SpringDataInjectionDemo/src/test/java/com/baeldung/didemo/SpringDataInjectionDemoApplicationTests.java

@@ -0,0 +1,65 @@
+package com.baeldung.didemo;
+
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import com.baeldung.didemo.model.Order;
+import com.baeldung.didemo.service.CustomerServiceConstructorDI;
+import com.baeldung.didemo.service.CustomerServiceFieldDI;
+import com.baeldung.didemo.service.CustomerServiceSetterDI;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class SpringDataInjectionDemoApplicationTests {
+
+    @Autowired
+    CustomerServiceConstructorDI constructorDI;
+
+    @Autowired
+    CustomerServiceFieldDI fieldDI;
+
+    @Autowired
+    CustomerServiceSetterDI setterDI;
+    
+	@Test
+	public void givenConstructorDI_whenNumberOfOrdersIsTwo_thenCorrect() {
+	    List<Order> orders = constructorDI.getCustomerOrders(1l);
+	    Assert.assertNotNull(orders);
+	    Assert.assertTrue(orders.size() == 2);
+	}
+	
+	@Test
+    public void givenFieldDI_whenNumberOfOrdersIsTwo_thenCorrect() {
+        List<Order> orders = fieldDI.getCustomerOrders(1l);
+        Assert.assertNotNull(orders);
+        Assert.assertTrue(orders.size() == 2);
+    }
+	
+	@Test
+    public void givenSetterDI_whenNumberOfOrdersIsTwo_thenCorrect() {
+        List<Order> orders = setterDI.getCustomerOrders(1l);
+        Assert.assertNotNull(orders);
+        Assert.assertTrue(orders.size() == 2);
+    }
+	
+	@Test
+    public void givenAllThreeTypesOfDI_whenNumberOfOrdersIsEqualInAll_thenCorrect() {
+        List<Order> ordersSetter = setterDI.getCustomerOrders(1l);
+        List<Order> ordersConstructor = constructorDI.getCustomerOrders(1l);
+        List<Order> ordersField = fieldDI.getCustomerOrders(1l);
+        
+        Assert.assertNotNull(ordersSetter);
+        Assert.assertNotNull(ordersConstructor);
+        Assert.assertNotNull(ordersField);
+        Assert.assertTrue(ordersSetter.size() == 2 && ordersConstructor.size() == ordersSetter.size() && ordersField.size() == ordersSetter.size());
+    }
+	
+	
+
+}

call-all-getters/.gitignore

@@ -0,0 +1,24 @@
+target/
+!.mvn/wrapper/maven-wrapper.jar
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+nbproject/private/
+build/
+nbbuild/
+dist/
+nbdist/
+.nb-gradle/

call-all-getters/pom.xml

@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>baeldung</groupId>
+	<artifactId>call-all-getters</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<packaging>jar</packaging>
+
+	<name>call-all-getters</name>
+	<description>Calling all getters using Introspector</description>
+
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>1.5.3.RELEASE</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+
+</project>

call-all-getters/src/main/java/com/baeldung/CallAllGettersApplication.java

@@ -0,0 +1,18 @@
+package com.baeldung;
+
+import java.util.List;
+
+import com.baeldung.reflection.model.Customer;
+import com.baeldung.reflection.util.Utils;
+
+public class CallAllGettersApplication {
+
+	public static void main(String[] args) throws Exception {
+	    
+	    Customer customer = new Customer(1, "Himanshu", null, null);
+	    List<String> nullProps = Utils.getNullPropertiesList(customer);
+	    System.out.println(nullProps);
+	}
+	
+	
+}

call-all-getters/src/main/java/com/baeldung/reflection/model/Customer.java

@@ -0,0 +1,63 @@
+package com.baeldung.reflection.model;
+
+/**
+ * 
+ * @author himanshumantri
+ *
+ */
+public class Customer {
+
+    private Integer id;
+    private String name;
+    private String emailId;
+    private Long phoneNumber;
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getEmailId() {
+        return emailId;
+    }
+
+    public void setEmailId(String emailId) {
+        this.emailId = emailId;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append("Customer [id=").append(id).append(", name=").append(name).append(", emailId=").append(emailId).append(", phoneNumber=")
+                .append(phoneNumber).append("]");
+        return builder.toString();
+    }
+
+    public Customer(Integer id, String name, String emailId, Long phoneNumber) {
+        super();
+        this.id = id;
+        this.name = name;
+        this.emailId = emailId;
+        this.phoneNumber = phoneNumber;
+    }
+
+    public Long getPhoneNumber() {
+        return phoneNumber;
+    }
+
+    public void setPhoneNumber(Long phoneNumber) {
+        this.phoneNumber = phoneNumber;
+    }
+
+}

call-all-getters/src/main/java/com/baeldung/reflection/util/Utils.java

@@ -0,0 +1,43 @@
+package com.baeldung.reflection.util;
+
+import java.beans.Introspector;
+import java.beans.PropertyDescriptor;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+
+import com.baeldung.reflection.model.Customer;
+
+public class Utils {
+
+    public static List<String> getNullPropertiesList(Customer customer) throws Exception {
+        PropertyDescriptor[] propDescArr = Introspector.getBeanInfo(Customer.class, Object.class).getPropertyDescriptors();
+        List<PropertyDescriptor>  propDescList = Arrays.asList(propDescArr);
+        
+        List<String> nullProps = propDescList.stream()
+                                        .filter(nulls(customer))
+                                        .map(PropertyDescriptor::getName)
+                                        .collect(Collectors.toList());
+        return nullProps;
+    }
+
+    private static Predicate<PropertyDescriptor> nulls(Customer customer) {
+        Predicate<PropertyDescriptor> isNull = new Predicate<PropertyDescriptor>() {
+            @Override
+            public boolean test(PropertyDescriptor pd) {
+                Method getterMethod = pd.getReadMethod();
+                boolean result = false;
+                try {
+                    result = (getterMethod != null && getterMethod.invoke(customer) == null);
+                } catch (Exception e) {
+                    // Handle the exception
+                    e.printStackTrace();
+                }
+                return result;
+            }
+        };
+        return isNull;
+    }
+}

call-all-getters/src/test/java/com/baeldung/CallAllGettersApplicationTests.java

@@ -0,0 +1,26 @@
+package com.baeldung;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.baeldung.reflection.model.Customer;
+import com.baeldung.reflection.util.Utils;
+
+public class CallAllGettersApplicationTests {
+
+	@Test
+	public void givenCustomer_whenAFieldIsNull_thenFieldNameInResult() throws Exception {
+	    Customer customer = new Customer(1, "Himanshu", null, null);
+	    
+	    List<String> result = Utils.getNullPropertiesList(customer);
+	    List<String> expectedFieldNames = Arrays.asList("emailId","phoneNumber");
+	    
+        Assert.assertTrue(result.size() == expectedFieldNames.size());
+        Assert.assertTrue(result.containsAll(expectedFieldNames));
+        
+	}
+
+}

collectionutils/pom.xml

@@ -0,0 +1,33 @@
+<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>baeldung</groupId>
+  <artifactId>collectionutils</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+  <name>collectionutils-guide</name>
+  <description>A guide to Apache Commons CollectionUtils</description>
+  
+  <properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+	</properties>
+
+	<dependencies>
+		<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-collections4 -->
+		<dependency>
+		    <groupId>org.apache.commons</groupId>
+		    <artifactId>commons-collections4</artifactId>
+		    <version>4.1</version>
+		</dependency>
+		
+		<!-- https://mvnrepository.com/artifact/junit/junit -->
+		<dependency>
+		    <groupId>junit</groupId>
+		    <artifactId>junit</artifactId>
+		    <version>4.12</version>
+		    <scope>test</scope>
+		</dependency>
+		
+
+	</dependencies>
+</project>

collectionutils/src/main/java/com/baeldung/collectionutilsguide/model/Address.java

@@ -0,0 +1,37 @@
+package com.baeldung.collectionutilsguide.model;
+
+public class Address {
+
+    String locality;
+    String city;
+
+    public String getLocality() {
+        return locality;
+    }
+
+    public void setLocality(String locality) {
+        this.locality = locality;
+    }
+
+    public String getCity() {
+        return city;
+    }
+
+    public void setCity(String city) {
+        this.city = city;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append("Address [locality=").append(locality).append(", city=").append(city).append("]");
+        return builder.toString();
+    }
+
+    public Address(String locality, String city) {
+        super();
+        this.locality = locality;
+        this.city = city;
+    }
+
+}

collectionutils/src/main/java/com/baeldung/collectionutilsguide/model/Customer.java

@@ -0,0 +1,81 @@
+package com.baeldung.collectionutilsguide.model;
+
+public class Customer implements Comparable<Customer> {
+
+    Integer id;
+    String name;
+    Address address;
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Address getAddress() {
+        return address;
+    }
+
+    public void setAddress(Address address) {
+        this.address = address;
+    }
+
+    public Customer(Integer id, String name, String locality, String city) {
+        super();
+        this.id = id;
+        this.name = name;
+        this.address = new Address(locality, city);
+    }
+    
+    public Customer(String name) {
+        super();
+        this.name = name;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((name == null) ? 0 : name.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        Customer other = (Customer) obj;
+        if (name == null) {
+            if (other.name != null)
+                return false;
+        } else if (!name.equals(other.name))
+            return false;
+        return true;
+    }
+
+    public int compareTo(Customer o) {
+        return this.name.compareTo(o.getName());
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append("Customer [id=").append(id).append(", name=").append(name).append("]");
+        return builder.toString();
+    }
+
+}

collectionutils/src/pom.xml

@@ -0,0 +1,33 @@
+<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>baeldung</groupId>
+  <artifactId>collectionutils</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+  <name>collectionutils-guide</name>
+  <description>A guide to Apache Commons CollectionUtils</description>
+  
+  <properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+	</properties>
+
+	<dependencies>
+		<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-collections4 -->
+		<dependency>
+		    <groupId>org.apache.commons</groupId>
+		    <artifactId>commons-collections4</artifactId>
+		    <version>4.1</version>
+		</dependency>
+		
+		<!-- https://mvnrepository.com/artifact/junit/junit -->
+		<dependency>
+		    <groupId>junit</groupId>
+		    <artifactId>junit</artifactId>
+		    <version>4.12</version>
+		    <scope>test</scope>
+		</dependency>
+		
+
+	</dependencies>
+</project>

collectionutils/src/test/java/collectionutils/CollectionUtilsGuideTest.java

@@ -0,0 +1,135 @@
+package collectionutils;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.LinkedList;
+import java.util.List;
+
+import org.apache.commons.collections4.Closure;
+import org.apache.commons.collections4.CollectionUtils;
+import org.apache.commons.collections4.Predicate;
+import org.apache.commons.collections4.Transformer;
+import org.junit.Test;
+
+import com.baeldung.collectionutilsguide.model.Address;
+import com.baeldung.collectionutilsguide.model.Customer;
+
+public class CollectionUtilsGuideTest {
+    
+    Customer customer1 = new Customer(1, "Daniel", "locality1", "city1");
+    Customer customer2 = new Customer(2, "Fredrik", "locality2", "city2");
+    Customer customer3 = new Customer(3, "Kyle", "locality3", "city3");
+    Customer customer4 = new Customer(4, "Bob", "locality4", "city4");
+    Customer customer5 = new Customer(5, "Cat", "locality5", "city5");
+    Customer customer6 = new Customer(6, "John", "locality6", "city6");
+    
+    List<Customer> list1 = Arrays.asList(customer1, customer2, customer3);
+    List<Customer> list2 = Arrays.asList(customer4, customer5, customer6);
+    List<Customer> list3 = Arrays.asList(customer1, customer2);
+    
+    List<Customer> linkedList1 = new LinkedList<Customer>(list1);
+    
+    @Test
+    public void givenList_WhenAddIgnoreNull_thenNoNullAdded() {
+        CollectionUtils.addIgnoreNull(list1, null);
+        assertFalse(list1.contains(null));
+    }
+    
+    @Test
+    public void givenTwoSortedLists_WhenCollated_thenSorted() {
+        List<Customer> sortedList = CollectionUtils.collate(list1, list2);
+        assertTrue(sortedList.get(0).getName().equals("Bob"));
+        assertTrue(sortedList.get(2).getName().equals("Daniel"));
+    }
+    
+    @Test
+    public void givenListOfCustomers_whenTransformed_thenListOfAddress() {
+        Collection<Address> addressCol = CollectionUtils.collect(list1, new Transformer<Customer, Address>() {
+            public Address transform(Customer customer) {
+                return customer.getAddress();
+            }
+        });
+        
+        List<Address> addressList = new ArrayList<Address>(addressCol);
+        assertTrue(addressList.size() == 3);
+        assertTrue(addressList.get(0).getLocality().equals("locality1"));
+    }
+    
+    @Test
+    public void givenCustomerList_WhenCountMatches_thenCorrect() {
+        int result = CollectionUtils.countMatches(list1, new Predicate<Customer>() {
+            public boolean evaluate(Customer customer) {
+                return Arrays.asList("Daniel","Kyle").contains(customer.getName());
+            }
+        });
+        assertTrue(result == 2);
+    }
+    
+    @Test
+    public void givenCustomerList_WhenFiltered_thenCorrectSize() {
+        
+        boolean isModified = CollectionUtils.filter(linkedList1, new Predicate<Customer>() {
+            public boolean evaluate(Customer customer) {
+                return Arrays.asList("Daniel","Kyle").contains(customer.getName());
+            }
+        });
+        
+        //filterInverse does the opposite. It removes the element from the list if the Predicate returns true
+        //select and selectRejected work the same way except that they do not remove elements from the given collection and return a new collection 
+        
+        assertTrue(isModified && linkedList1.size() == 2);
+    }
+    
+    @Test
+    public void givenCustomerList_WhenForAllDoSetNameNull_thenNameNull() {
+        CollectionUtils.forAllDo(list1, new Closure<Customer>() {
+            public void execute(Customer customer) {
+                customer.setName(null);
+            }
+        });
+        
+        // forAllButLast does the same except for the last element in the collection
+        assertTrue(list1.get(0).getName() == null);
+    }
+    
+    @Test
+    public void givenNonEmptyList_WhenCheckedIsNotEmpty_thenTrue() {
+        List<Customer> emptyList = new ArrayList<Customer>();
+        List<Customer> nullList = null;
+        
+        //Very handy at times where we want to check if a collection is not null and not empty too.
+        //isNotEmpty does the opposite. Handy because using ! operator on isEmpty makes it missable while reading
+        assertTrue(CollectionUtils.isNotEmpty(list1));
+        assertTrue(CollectionUtils.isEmpty(nullList));
+        assertTrue(CollectionUtils.isEmpty(emptyList));
+    }
+    
+    @Test
+    public void givenCustomerListAndASubcollection_WhenChecked_thenTrue() {
+        assertTrue(CollectionUtils.isSubCollection(list3, list1));
+    }
+    
+    @Test
+    public void givenTwoLists_WhenIntersected_thenCheckSize() {
+        Collection<Customer> intersection = CollectionUtils.intersection(list1, list3);
+        assertTrue(intersection.size() == 2);
+    }
+    
+    @Test
+    public void givenTwoLists_WhenSubtracted_thenCheckElementNotPresentInA() {
+        Collection<Customer> result = CollectionUtils.subtract(list1, list3);
+        assertFalse(result.contains(customer1));
+    }
+    
+    @Test
+    public void givenTwoLists_WhenUnioned_thenCheckElementPresentInResult() {
+        Collection<Customer> union = CollectionUtils.union(list1, list2);
+        assertTrue(union.contains(customer1));
+        assertTrue(union.contains(customer4));
+    }
+    
+}

spring-check-if-a-property-is-null/.gitignore

@@ -0,0 +1,24 @@
+target/
+!.mvn/wrapper/maven-wrapper.jar
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+nbproject/private/
+build/
+nbbuild/
+dist/
+nbdist/
+.nb-gradle/

spring-check-if-a-property-is-null/pom.xml

@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>baeldung</groupId>
+	<artifactId>spring-check-null</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<packaging>jar</packaging>
+
+	<name>spring-check-if-a-property-is-null</name>
+	<description>Calling getters using Introspector</description>
+
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>1.5.3.RELEASE</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+
+</project>

spring-check-if-a-property-is-null/src/main/java/com/baeldung/SpringCheckIfAPropertyIsNullApplication.java

@@ -0,0 +1,21 @@
+package com.baeldung;
+
+import java.util.List;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+import com.baeldung.reflection.model.Customer;
+import com.baeldung.reflection.util.Utils;
+
+@SpringBootApplication
+public class SpringCheckIfAPropertyIsNullApplication {
+
+	public static void main(String[] args) throws Exception {
+	    
+	    Customer customer = new Customer(1, "Himanshu", null, null);
+	    List<String> nullProps = Utils.getNullPropertiesList(customer);
+	    System.out.println(nullProps);
+	}
+	
+	
+}

spring-check-if-a-property-is-null/src/main/java/com/baeldung/reflection/model/Customer.java

@@ -0,0 +1,63 @@
+package com.baeldung.reflection.model;
+
+/**
+ * 
+ * @author himanshumantri
+ *
+ */
+public class Customer {
+
+    private Integer id;
+    private String name;
+    private String emailId;
+    private Long phoneNumber;
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getEmailId() {
+        return emailId;
+    }
+
+    public void setEmailId(String emailId) {
+        this.emailId = emailId;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append("Customer [id=").append(id).append(", name=").append(name).append(", emailId=").append(emailId).append(", phoneNumber=")
+                .append(phoneNumber).append("]");
+        return builder.toString();
+    }
+
+    public Customer(Integer id, String name, String emailId, Long phoneNumber) {
+        super();
+        this.id = id;
+        this.name = name;
+        this.emailId = emailId;
+        this.phoneNumber = phoneNumber;
+    }
+
+    public Long getPhoneNumber() {
+        return phoneNumber;
+    }
+
+    public void setPhoneNumber(Long phoneNumber) {
+        this.phoneNumber = phoneNumber;
+    }
+
+}

spring-check-if-a-property-is-null/src/main/java/com/baeldung/reflection/util/Utils.java

@@ -0,0 +1,34 @@
+package com.baeldung.reflection.util;
+
+import java.beans.Introspector;
+import java.beans.PropertyDescriptor;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import com.baeldung.reflection.model.Customer;
+
+public class Utils {
+
+    public static List<String> getNullPropertiesList(Customer customer) throws Exception {
+        PropertyDescriptor[] propDescArr = Introspector.getBeanInfo(Customer.class, Object.class).getPropertyDescriptors();
+        List<PropertyDescriptor>  propDescList = Arrays.asList(propDescArr);
+        
+        List<String> nullProps = new ArrayList<String>();
+        
+        propDescList.stream().forEach(p -> {
+            Method getterMethod = p.getReadMethod();
+            try {
+                if (getterMethod != null && getterMethod.invoke(customer) == null) {
+                    // If the value if null for that field
+                    nullProps.add(p.getName());
+                }
+            } catch (Exception e) {
+                // Handle the exception
+                e.printStackTrace();
+            }
+        });
+        return nullProps;
+    }
+}

spring-check-if-a-property-is-null/src/test/java/com/baeldung/SpringCheckIfAPropertyIsNullApplicationTests.java

@@ -0,0 +1,31 @@
+package com.baeldung;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import com.baeldung.reflection.model.Customer;
+import com.baeldung.reflection.util.Utils;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class SpringCheckIfAPropertyIsNullApplicationTests {
+
+	@Test
+	public void givenCustomer_whenAFieldIsNull_thenFieldNameInResult() throws Exception {
+	    Customer customer = new Customer(1, "Himanshu", null, null);
+	    
+	    List<String> result = Utils.getNullPropertiesList(customer);
+	    List<String> expectedFieldNames = Arrays.asList("emailId","phoneNumber");
+	    
+        Assert.assertTrue(result.size() == expectedFieldNames.size());
+        Assert.assertTrue(result.containsAll(expectedFieldNames));
+        
+	}
+
+}