BAEL-4070: Injecting List or Arrays from a Spring properties file

spring-boot-modules/spring-boot-properties/src/test/java/com/baeldung/properties/lists/ListsPropertiesIntegrationTest.java

@@ -0,0 +1,88 @@
+package com.baeldung.properties.lists;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.core.env.Environment;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = {SpringListPropertiesApplication.class})
+public class ListsPropertiesIntegrationTest {
+
+    @Value("${arrayOfStrings}")
+    private String[] arrayOfStrings;
+
+    @Value("${arrayOfStrings}")
+    private List<String> unexpectedListOfStrings;
+
+    @Value("#{'${arrayOfStrings}'.split(',')}")
+    private List<String> listOfStrings;
+
+    @Value("#{${listOfStrings}}")
+    private List<String> listOfStringsV2;
+
+    @Value("#{'${listOfStringsWithCustomDelimiter}'.split(';')}")
+    private List<String> listOfStringsWithCustomDelimiter;
+
+    @Value("#{'${listOfBooleans}'.split(',')}")
+    private List<Boolean> listOfBooleans;
+
+    @Value("#{'${listOfIntegers}'.split(',')}")
+    private List<Integer> listOfIntegers;
+
+    @Value("#{'${listOfCharacters}'.split(',')}")
+    private List<Character> listOfCharacters;
+
+    @Autowired
+    private Environment environment;
+
+    @Test
+    public void givenContextIsInitialized_ThenInjectedArrayContainsExpectedValues() {
+        assertEquals(arrayOfStrings, new String[] {"Baeldung", "dot", "com"});
+    }
+
+    @Test
+    public void givenContextIsInitialized_ThenInjectedListContainsUnexpectedValues() {
+        assertEquals(unexpectedListOfStrings, Collections.singletonList("Baeldung,dot,com"));
+    }
+
+    @Test
+    public void givenContextIsInitialized_ThenInjectedListContainsExpectedValues() {
+        assertEquals(listOfStrings, Arrays.asList("Baeldung", "dot", "com"));
+    }
+
+    @Test
+    public void givenContextIsInitialized_ThenInjectedListV2ContainsExpectedValues() {
+        assertEquals(listOfStringsV2, Arrays.asList("Baeldung", "dot", "com"));
+    }
+
+    @Test
+    public void givenContextIsInitialized_ThenInjectedListWithCustomDelimiterContainsExpectedValues() {
+        assertEquals(listOfStringsWithCustomDelimiter, Arrays.asList("Baeldung", "dot", "com"));
+    }
+
+    @Test
+    public void givenContextIsInitialized_ThenInjectedListOfBasicTypesContainsExpectedValues() {
+        assertEquals(listOfBooleans, Arrays.asList(false, false, true));
+        assertEquals(listOfIntegers, Arrays.asList(1, 2, 3, 4));
+        assertEquals(listOfCharacters, Arrays.asList('a', 'b', 'c'));
+    }
+
+    @Test
+    public void givenContextIsInitialized_WhenReadingFromEnvironment_ThenPropertiesHaveExpectedValues() {
+        String[] arrayOfStrings = environment.getProperty("arrayOfStrings", String[].class);
+        List<String> listOfStrings = (List<String>)environment.getProperty("arrayOfStrings", List.class);
+
+        assertEquals(arrayOfStrings, new String[] {"Baeldung", "dot", "com"});
+        assertEquals(listOfStrings, Arrays.asList("Baeldung", "dot", "com"));
+    }
+}

spring-boot-modules/spring-boot-properties/src/test/java/com/baeldung/properties/lists/SpringListPropertiesApplication.java

@@ -0,0 +1,10 @@
+package com.baeldung.properties.lists;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.PropertySource;
+
+@Configuration
+@PropertySource(value = "lists.properties")
+public class SpringListPropertiesApplication {
+
+}

spring-boot-modules/spring-boot-properties/src/test/resources/lists.properties

@@ -0,0 +1,6 @@
+arrayOfStrings=Baeldung,dot,com
+listOfStrings={'Baeldung','dot','com'}
+listOfStringsWithCustomDelimiter=Baeldung;dot;com
+listOfBooleans=false,false,true
+listOfIntegers=1,2,3,4
+listOfCharacters=a,b,c