BAEL-5191-JsonNode-Get-All-Keys-From-A-Json-Structure (#11451)
* BAEL-5191-JsonNode-Get-All-Keys-From-A-Json-Structure * Added test cases for GetAllKeysFromJSON class methods * Updated test class name
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priya-soni
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package com.baeldung.jackson.jsonnode;
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import java.io.IOException;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Map;
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import java.util.Map.Entry;
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import com.fasterxml.jackson.core.JsonFactory;
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import com.fasterxml.jackson.core.JsonParser;
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import com.fasterxml.jackson.core.JsonProcessingException;
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import com.fasterxml.jackson.core.JsonToken;
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import com.fasterxml.jackson.core.type.TypeReference;
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import com.fasterxml.jackson.databind.JsonNode;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import com.fasterxml.jackson.databind.node.ArrayNode;
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public class GetAllKeysFromJSON {
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public static List<String> getKeysInJsonUsingMaps(String json, ObjectMapper mapper) {
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List<String> keys = new ArrayList<>();
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try {
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Map<String, Object> jsonElements = mapper.readValue(json, new TypeReference<Map<String, Object>>() {
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});
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getAllKeys(jsonElements, keys);
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return keys;
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} catch (JsonProcessingException e) {
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e.printStackTrace();
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}
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return keys;
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}
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public static void getAllKeys(Map<String, Object> jsonElements, List<String> keys) {
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jsonElements.entrySet()
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.forEach(entry -> {
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keys.add(entry.getKey());
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if (entry.getValue() instanceof Map) {
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Map<String, Object> map = (Map<String, Object>) entry.getValue();
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getAllKeys(map, keys);
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} else if (entry.getValue() instanceof List) {
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List<?> list = (List<?>) entry.getValue();
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list.forEach(listEntry -> {
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if (listEntry instanceof Map) {
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Map<String, Object> map = (Map<String, Object>) listEntry;
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getAllKeys(map, keys);
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}
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});
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}
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});
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}
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public static List<String> getKeysInJsonUsingJsonNodeFieldNames(String json, ObjectMapper mapper) {
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List<String> keys = new ArrayList<>();
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try {
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JsonNode jsonNode = mapper.readTree(json);
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Iterator<String> iterator = jsonNode.fieldNames();
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iterator.forEachRemaining(e -> keys.add(e));
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} catch (JsonProcessingException e) {
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e.printStackTrace();
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}
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return keys;
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}
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public static List<String> getAllKeysInJsonUsingJsonNodeFieldNames(String json, ObjectMapper mapper) {
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List<String> keys = new ArrayList<>();
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try {
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JsonNode jsonNode = mapper.readTree(json);
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getAllKeysUsingJsonNodeFieldNames(jsonNode, keys);
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} catch (JsonProcessingException e) {
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e.printStackTrace();
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}
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return keys;
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}
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public static List<String> getAllKeysInJsonUsingJsonNodeFields(String json, ObjectMapper mapper) {
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List<String> keys = new ArrayList<>();
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try {
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JsonNode jsonNode = mapper.readTree(json);
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getAllKeysUsingJsonNodeFields(jsonNode, keys);
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} catch (JsonProcessingException e) {
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e.printStackTrace();
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}
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return keys;
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}
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public static void getAllKeysUsingJsonNodeFields(JsonNode jsonNode, List<String> keys) {
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if (jsonNode.isObject()) {
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Iterator<Entry<String, JsonNode>> fields = jsonNode.fields();
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fields.forEachRemaining(field -> {
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keys.add(field.getKey());
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getAllKeysUsingJsonNodeFieldNames((JsonNode) field.getValue(), keys);
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});
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} else if (jsonNode.isArray()) {
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ArrayNode arrayField = (ArrayNode) jsonNode;
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arrayField.forEach(node -> {
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getAllKeysUsingJsonNodeFieldNames(node, keys);
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});
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}
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}
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public static void getAllKeysUsingJsonNodeFieldNames(JsonNode jsonNode, List<String> keys) {
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if (jsonNode.isObject()) {
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Iterator<String> fieldNames = jsonNode.fieldNames();
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fieldNames.forEachRemaining(fieldName -> {
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keys.add(fieldName);
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getAllKeysUsingJsonNodeFieldNames(jsonNode.get(fieldName), keys);
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});
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} else if (jsonNode.isArray()) {
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ArrayNode arrayField = (ArrayNode) jsonNode;
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arrayField.forEach(node -> {
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getAllKeysUsingJsonNodeFieldNames(node, keys);
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});
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}
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}
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public static List<String> getKeysInJsonUsingJsonParser(String json, ObjectMapper mapper) {
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List<String> keys = new ArrayList<>();
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try {
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JsonNode jsonNode = mapper.readTree(json);
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JsonParser jsonParser = jsonNode.traverse();
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while (!jsonParser.isClosed()) {
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if (jsonParser.nextToken() == JsonToken.FIELD_NAME) {
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keys.add((jsonParser.getCurrentName()));
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}
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}
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} catch (JsonProcessingException e) {
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e.printStackTrace();
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} catch (IOException e) {
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e.printStackTrace();
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}
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return keys;
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}
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public static List<String> getKeysInJsonUsingJsonParser(String json) {
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List<String> keys = new ArrayList<>();
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try {
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JsonFactory factory = new JsonFactory();
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JsonParser jsonParser = factory.createParser(json);
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while (!jsonParser.isClosed()) {
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if (jsonParser.nextToken() == JsonToken.FIELD_NAME) {
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keys.add((jsonParser.getCurrentName()));
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}
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}
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} catch (JsonProcessingException e) {
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e.printStackTrace();
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} catch (IOException e) {
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e.printStackTrace();
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}
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return keys;
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}
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}
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@ -0,0 +1,56 @@
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package com.baeldung.jackson.jsonnode;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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import java.util.List;
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import org.junit.jupiter.api.Test;
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import com.fasterxml.jackson.databind.ObjectMapper;
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public class GetAllKeysFromJSONUnitTest {
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private static String json = "{\r\n" + " \"Name\":\"Craig\",\r\n" + " \"Age\":10,\r\n" + " \"BookInterests\":[\r\n" + " {\r\n" + " \"Book\":\"The Kite Runner\",\r\n" + " \"Author\":\"Khaled Hosseini\"\r\n" + " },\r\n"
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+ " {\r\n" + " \"Book\":\"Harry Potter\",\r\n" + " \"Author\":\"J. K. Rowling\"\r\n" + " }\r\n" + " ],\r\n" + " \"FoodInterests\":{\r\n" + " \"Breakfast\":[\r\n" + " {\r\n"
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+ " \"Bread\":\"Whole wheat\",\r\n" + " \"Beverage\":\"Fruit juice\"\r\n" + " },\r\n" + " {\r\n" + " \"Sandwich\":\"Vegetable Sandwich\",\r\n" + " \"Beverage\":\"Coffee\"\r\n"
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+ " }\r\n" + " ]\r\n" + " }\r\n" + "}";
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private static ObjectMapper mapper = new ObjectMapper();
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// Top level keys : [Name, Age, BookInterests, FoodInterests]
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// All keys: [Name, Age, BookInterests, Book, Author, Book, Author, FoodInterests, Breakfast, Bread, Beverage, Sandwich, Beverage]
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@Test
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public void givenAJsonNode_whenUsingFieldNamesMethod_thenWeGetTopFieldNames() {
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List<String> keys = GetAllKeysFromJSON.getKeysInJsonUsingJsonNodeFieldNames(json, mapper);
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assertEquals(4, keys.size());
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}
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@Test
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public void givenAJsonNode_whenUsingFieldNamesMethodForAllNodes_thenWeGetAllFieldNames() {
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List<String> keys = GetAllKeysFromJSON.getAllKeysInJsonUsingJsonNodeFieldNames(json, mapper);
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assertEquals(13, keys.size());
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}
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@Test
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public void givenAJsonNode_whenUsingFieldsMethod_thenWeGetAllFieldNames() {
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List<String> keys = GetAllKeysFromJSON.getAllKeysInJsonUsingJsonNodeFields(json, mapper);
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assertEquals(13, keys.size());
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}
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@Test
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public void givenAJsonNode_whenUsingJsonParserMethod_thenWeGetAllFieldNames() {
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List<String> keys = GetAllKeysFromJSON.getKeysInJsonUsingJsonParser(json, mapper);
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assertEquals(13, keys.size());
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keys = GetAllKeysFromJSON.getKeysInJsonUsingJsonParser(json);
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assertEquals(13, keys.size());
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}
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@Test
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public void givenAJsonNode_whenUsingMaps_thenWeGetAllFieldNames() {
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List<String> keys = GetAllKeysFromJSON.getKeysInJsonUsingMaps(json, mapper);
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assertEquals(13, keys.size());
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}
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}
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