Merge pull request #14770 from niket17590/feature/BAEL-6963-ArrayList

BAEL-6963 - ArrayList with Multiple Object Types

core-java-modules/core-java-collections-array-list-2/README.md

@@ -0,0 +1,6 @@
+## Core Java Collections ArrayList
+
+This module contains articles about the Java ArrayList collection
+
+### Relevant Articles:
+- [Create an ArrayList with Multiple Object Types](https://www.baeldung.com/arraylist-with-multiple-object-types)

core-java-modules/core-java-collections-array-list-2/pom.xml

@@ -0,0 +1,32 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-collections-array-list-2</artifactId>
+    <name>core-java-collections-array-list-2</name>
+    <packaging>jar</packaging>
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+    
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>${maven-compiler-plugin.source}</source>
+                    <target>${maven-compiler-plugin.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+    
+    <properties>
+        <maven-compiler-plugin.source>17</maven-compiler-plugin.source>
+        <maven-compiler-plugin.target>17</maven-compiler-plugin.target>
+    </properties>
+</project>

core-java-modules/core-java-collections-array-list-2/src/main/java/com/baeldung/list/multipleobjecttypes/AlternativeMultipeTypeList.java

@@ -0,0 +1,51 @@
+package com.baeldung.list.multipleobjecttypes;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+import java.util.function.Predicate;
+
+public class AlternativeMultipeTypeList {
+
+    public static void main(String[] args) {
+        // List of Parent Class
+        ArrayList<Number> myList = new ArrayList<>();
+        myList.add(1.2);
+        myList.add(2);
+        myList.add(-3.5);
+
+        // List of Interface type
+        ArrayList<Map> diffMapList = new ArrayList<>();
+        diffMapList.add(new HashMap<>());
+        diffMapList.add(new TreeMap<>());
+        diffMapList.add(new LinkedHashMap<>());
+
+        // List of Custom Object
+        ArrayList<CustomObject> objList = new ArrayList<>();
+        objList.add(new CustomObject("String"));
+        objList.add(new CustomObject(2));
+
+        // List via Functional Interface
+        List<Object> dataList = new ArrayList<>();
+
+        Predicate<Object> myPredicate = inputData -> (inputData instanceof String || inputData instanceof Integer);
+
+        UserFunctionalInterface myInterface = (listObj, data) -> {
+            if (myPredicate.test(data))
+                listObj.add(data);
+            else
+                System.out.println("Skipping input as data not allowed for class: " + data.getClass()
+                    .getSimpleName());
+            return listObj;
+        };
+
+        myInterface.addToList(dataList, Integer.valueOf(2));
+        myInterface.addToList(dataList, Double.valueOf(3.33));
+        myInterface.addToList(dataList, "String Value");
+        myInterface.printList(dataList);
+    }
+
+}

core-java-modules/core-java-collections-array-list-2/src/main/java/com/baeldung/list/multipleobjecttypes/CustomObject.java

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+package com.baeldung.list.multipleobjecttypes;
+
+public class CustomObject {
+    String classData;
+    Integer intData;
+
+    CustomObject(String classData) {
+        this.classData = classData;
+    }
+
+    CustomObject(Integer intData) {
+        this.intData = intData;
+    }
+
+    public String getClassData() {
+        return this.classData;
+    }
+
+    public Integer getIntData() {
+        return this.intData;
+    }
+}

core-java-modules/core-java-collections-array-list-2/src/main/java/com/baeldung/list/multipleobjecttypes/MultipleObjectTypeArrayList.java

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+package com.baeldung.list.multipleobjecttypes;
+
+import java.math.BigInteger;
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class MultipleObjectTypeArrayList {
+
+    public static void main(String[] args) {
+
+        ArrayList<Object> multiTypeList = new ArrayList<>();
+
+        multiTypeList.add(Integer.valueOf(10));
+        multiTypeList.add(Double.valueOf(11.5));
+        multiTypeList.add("String Data");
+        multiTypeList.add(Arrays.asList(1, 2, 3));
+        multiTypeList.add(new CustomObject("Class Data"));
+        multiTypeList.add(BigInteger.valueOf(123456789));
+        multiTypeList.add(LocalDate.of(2023, 9, 19));
+
+        for (Object dataObj : multiTypeList) {
+            if (dataObj instanceof Integer intData)
+                System.out.println("Integer Data : " + intData);
+            else if (dataObj instanceof Double doubleData)
+                System.out.println("Double Data : " + doubleData);
+            else if (dataObj instanceof String stringData)
+                System.out.println("String Data : " + stringData);
+            else if (dataObj instanceof List<?> intList)
+                System.out.println("List Data : " + intList);
+            else if (dataObj instanceof CustomObject customObj)
+                System.out.println("CustomObject Data : " + customObj.getClassData());
+            else if (dataObj instanceof BigInteger bigIntData)
+                System.out.println("BigInteger Data : " + bigIntData);
+            else if (dataObj instanceof LocalDate localDate)
+                System.out.println("LocalDate Data : " + localDate.toString());
+        }
+    }
+}

core-java-modules/core-java-collections-array-list-2/src/main/java/com/baeldung/list/multipleobjecttypes/UserFunctionalInterface.java

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+package com.baeldung.list.multipleobjecttypes;
+
+import java.util.List;
+
+@FunctionalInterface
+public interface UserFunctionalInterface {
+
+    List<Object> addToList(List<Object> list, Object data);
+
+    default void printList(List<Object> dataList) {
+        for (Object data : dataList) {
+            if (data instanceof String stringData)
+                System.out.println("String Data: " + stringData);
+            if (data instanceof Integer intData)
+                System.out.println("Integer Data: " + intData);
+        }
+    }
+}

core-java-modules/pom.xml

@@ -28,13 +28,14 @@
         <!--<module>core-java-streams-2</module> -->
         <!--<module>core-java-sun</module> -->
         <module>core-java-9-improvements</module>
-        <module>core-java-collections-array-list</module>
         <module>core-java-9-streams</module>
         <module>core-java-9</module>
         <module>core-java-10</module>
         <module>core-java-11</module>
         <module>core-java-11-2</module>
         <module>core-java-11-3</module>
+        <module>core-java-collections-array-list</module>
+        <module>core-java-collections-array-list-2</module>
         <module>core-java-collections-list-4</module>
         <module>core-java-collections-list-5</module>
         <module>core-java-collections-maps-4</module>