Different types of dependency injection

spring-core/src/main/java/com/baeldung/ditypes/RegisterarConfig.java

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+package com.baeldung.ditypes;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@ComponentScan("com.baeldung.ditypes")
+public class RegisterarConfig {
+    @Bean
+    public User user() {
+        return new User("Alice", 1);
+    }
+}

spring-core/src/main/java/com/baeldung/ditypes/Registrar.java

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+package com.baeldung.ditypes;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class Registrar {
+    private User user;
+
+    @Autowired
+    public Registrar(User user) {
+        this.user = user;
+    }
+
+    public String register() {
+        return user.register();
+    }
+}

spring-core/src/main/java/com/baeldung/ditypes/User.java

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+package com.baeldung.ditypes;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public class User {
+
+    private String name;
+    private int id;
+
+    public User(String name, int id) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public String register() {
+        return "User" + id + ": " + name + " is registered";
+    }
+
+}

spring-core/src/test/java/com/baeldung/ditypes/RegisterarTest.java

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+package com.baeldung.ditypes;
+
+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;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = RegisterarConfig.class)
+public class RegisterarTest {
+
+    @Autowired
+    private Registrar reg;
+
+    @Autowired
+    private User user;
+
+    @Test
+    public void givenAutowiredAnnotation_whenSetOnField_thenRegistrarIsInjected() {
+        assertNotNull(reg);
+    }
+
+    @Test
+    public void givenAutowiredAnnotation_whenSetOnField_thenUserIsInjected() {
+        assertEquals("User1: Alice is registered", user.register());
+    }
+}