Different types of Bean Injection

spring-core/src/main/java/com/baeldung/beaninjectiontypes/BeanConfig.java

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+package com.baeldung.beaninjectiontypes;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+
+import com.baeldung.beaninjectiontypes.models.Family;
+
+@Configuration
+@ComponentScan("com.baeldung.beaninjectiontypes")
+public class BeanConfig {
+
+    @Bean
+    public Family family() {
+        return new Family("Ayo", "Kemi");
+    }
+
+}

spring-core/src/main/java/com/baeldung/beaninjectiontypes/ConstructorInjectionBean.java

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+package com.baeldung.beaninjectiontypes;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+import com.baeldung.beaninjectiontypes.models.Family;
+
+@Component
+public class ConstructorInjectionBean {
+
+    private Family family;
+
+    @Autowired
+    public ConstructorInjectionBean(Family family) {
+        this.family = family;
+    }
+
+    public int noOfChildren() {
+        return family.getChildren()
+            .size();
+    }
+
+    public void addChildToFamily(String childName) {
+        family.getChildren()
+            .add(childName);
+    }
+
+    public boolean isChildAlive(String childName) {
+        return family.getChildren()
+            .contains(childName);
+    }
+
+    public void killChild(String childName) {
+        family.getChildren()
+            .remove(childName);
+    }
+
+}

spring-core/src/main/java/com/baeldung/beaninjectiontypes/SetterInjectionBean.java

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+package com.baeldung.beaninjectiontypes;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+import com.baeldung.beaninjectiontypes.models.Family;
+
+@Component
+public class SetterInjectionBean {
+
+    private Family family;
+
+    @Autowired
+    public void setFamily(Family family) {
+        this.family = family;
+    }
+
+    public int noOfChildren() {
+        return family.getChildren()
+            .size();
+    }
+
+    public void addChildToFamily(String childName) {
+        family.getChildren()
+            .add(childName);
+    }
+
+    public boolean isChildAlive(String childName) {
+        return family.getChildren()
+            .contains(childName);
+    }
+
+    public void killChild(String childName) {
+        family.getChildren()
+            .remove(childName);
+    }
+
+}

spring-core/src/main/java/com/baeldung/beaninjectiontypes/models/Family.java

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+package com.baeldung.beaninjectiontypes.models;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Family {
+
+    private String father;
+    private String mother;
+    private List<String> children;
+
+    public Family(String father, String mother) {
+        this.father = father;
+        this.mother = mother;
+        this.children = new ArrayList<>();
+    }
+
+    public String getFather() {
+        return father;
+    }
+
+    public void setFather(String father) {
+        this.father = father;
+    }
+
+    public String getMother() {
+        return mother;
+    }
+
+    public void setMother(String mother) {
+        this.mother = mother;
+    }
+
+    public List<String> getChildren() {
+        return children;
+    }
+
+    public void setChildren(List<String> children) {
+        this.children = children;
+    }
+
+}

spring-core/src/test/java/com/baeldung/beaninjectiontypes/ConstructorInjectionBeanTest.java

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+package com.baeldung.beaninjectiontypes;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import com.baeldung.beaninjectiontypes.models.Family;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = { BeanConfig.class })
+public class ConstructorInjectionBeanTest {
+
+    @Autowired
+    private ConstructorInjectionBean constructorFamilyBean;
+
+    @Test
+    public void testConstructorInjectionBean() {
+        assertNotNull(constructorFamilyBean);
+    }
+
+    @Test
+    public void testNoOfChildren() {
+        assertTrue(constructorFamilyBean.noOfChildren() == 0);
+        constructorFamilyBean.addChildToFamily("Bimbo");
+        constructorFamilyBean.addChildToFamily("Bayo");
+        assertTrue(constructorFamilyBean.noOfChildren() == 2);
+    }
+
+    @Test
+    public void testAddChildToFamily() {
+        assertFalse(constructorFamilyBean.isChildAlive("Damola"));
+        constructorFamilyBean.addChildToFamily("Damola");
+        assertTrue(constructorFamilyBean.isChildAlive("Damola"));
+        constructorFamilyBean.killChild("Damola");
+    }
+
+}

spring-core/src/test/java/com/baeldung/beaninjectiontypes/SetterInjectionBeanTest.java

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+package com.baeldung.beaninjectiontypes;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import com.baeldung.beaninjectiontypes.models.Family;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = { BeanConfig.class })
+public class SetterInjectionBeanTest {
+
+    @Autowired
+    private SetterInjectionBean setterFamilyBean;
+
+    @Test
+    public void testSetterInjectionBean() {
+        assertNotNull(setterFamilyBean);
+    }
+
+    @Test
+    public void testNoOfChildren() {
+        assertTrue(setterFamilyBean.noOfChildren() == 0);
+        setterFamilyBean.addChildToFamily("Bimbo");
+        setterFamilyBean.addChildToFamily("Bayo");
+        assertTrue(setterFamilyBean.noOfChildren() == 2);
+    }
+
+    @Test
+    public void testAddChildToFamily() {
+        assertFalse(setterFamilyBean.isChildAlive("Damola"));
+        setterFamilyBean.addChildToFamily("Damola");
+        assertTrue(setterFamilyBean.isChildAlive("Damola"));
+        setterFamilyBean.killChild("Damola");
+    }
+
+}