BAEL-6504: Convert Json Array to Java list (#14049)

json-modules/json-conversion/src/main/java/com/baeldung/jsonarraytolist/ConvertJsonArrayToList.java

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+package com.baeldung.jsonarraytolist;
+
+import java.lang.reflect.Type;
+import java.util.List;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+
+import entities.Product;
+
+public class ConvertJsonArrayToList {
+
+    public List<Product> convertJsonArrayUsingGsonLibrary(String jsonArray) {
+        Gson gson = new Gson();
+
+        Type listType = new TypeToken<List<Product>>() {}.getType();
+
+        List<Product> gsonList = gson.fromJson(jsonArray, listType);
+        return gsonList;
+    }
+
+    public List<Product> convertJsonArrayUsingJacksonLibrary(String jsonArray) throws JsonProcessingException {
+        ObjectMapper objectMapper = new ObjectMapper();
+
+        List<Product> typeReferenceList = objectMapper.readValue(jsonArray, new TypeReference<List<Product>>() {});
+        return typeReferenceList;
+    }
+}

json-modules/json-conversion/src/main/java/entities/Product.java

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+package entities;
+
+public class Product {
+
+    private int id;
+    private String name;
+    private String description;
+
+    public Product() {}
+
+    public Product(int id, String name, String description) {
+        this.id = id;
+        this.name = name;
+        this.description = description;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+}

json-modules/json-conversion/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

json-modules/json-conversion/src/test/java/com/baeldung/jsonarraytolist/ConvertJsonArrayToListUnitTest.java

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+package com.baeldung.jsonarraytolist;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.gson.Gson;
+
+import entities.Product;
+
+public class ConvertJsonArrayToListUnitTest {
+
+    private static ObjectMapper objectMapper;
+    private static List<Product> productList;
+    private ConvertJsonArrayToList obj;
+
+    @Before
+    public void setup() {
+        obj = new ConvertJsonArrayToList();
+        productList = getProducts();
+        objectMapper = new ObjectMapper();
+    }
+
+    private List<Product> getProducts() {
+        List<Product> productList = new ArrayList<>();
+        Product prod1 = new Product(1, "Icecream", "Sweet and cold");
+        Product prod2 = new Product(2, "Apple", "Red and sweet");
+        Product prod3 = new Product(3, "Carrot", "Good for eyes");
+        productList.add(prod1);
+        productList.add(prod2);
+        productList.add(prod3);
+        return productList;
+    }
+
+    @Test
+    public void whenUsingGsonLibrary_thenCompareTwoProducts() {
+        Gson gson = new Gson();
+        String jsonArray = gson.toJson(productList);
+        List<Product> arrList = obj.convertJsonArrayUsingGsonLibrary(jsonArray);
+        Assert.assertEquals(productList.get(0).getId(), arrList.get(0).getId());
+        Assert.assertEquals(productList.get(1).getDescription(), arrList.get(1).getDescription());
+        Assert.assertEquals(productList.get(2).getName(), arrList.get(2).getName());
+    }
+
+    @Test
+    public void whenUsingJacksonLibrary_thenCompareTwoProducts() throws JsonProcessingException {
+        String jsonArray = objectMapper.writeValueAsString(productList);
+        List<Product> arrList = obj.convertJsonArrayUsingJacksonLibrary(jsonArray);
+
+        Assert.assertEquals(productList.get(0).getId(), arrList.get(0).getId());
+        Assert.assertEquals(productList.get(1).getDescription(), arrList.get(1).getDescription());
+        Assert.assertEquals(productList.get(2).getName(), arrList.get(2).getName());
+    }
+
+}

json-modules/json-conversion/src/test/resources/.gitignore

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+*.class
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+
+# Packaged files #
+*.jar
+*.war
+*.ear

json-modules/json-conversion/src/test/resources/logback-test.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <logger name="org.springframework" level="WARN"/>
+    <logger name="org.springframework.transaction" level="WARN"/>
+
+    <!-- in order to debug some marshalling issues, this needs to be TRACE -->
+    <logger name="org.springframework.web.servlet.mvc" level="WARN"/>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT"/>
+    </root>
+</configuration>