Feature/1.0.1 (#3)

* Added tests for JsonObject and fixed a couple bugs that the tests found.

* Added tests for JsonArray.
Improved error messaging for when JsonElement type is not of desired type.

* Small helpers added to JsonArray and JsonObject to convert to JsonElement.

* Added JsonMapper interface with some default methods implemented for converting between JsonObject or JsonArray into java objects

* SolaJson now has several methods that utilize new JsonMapper.
Fixed another bug in JsonElement.

build.gradle.kts

@@ -2,7 +2,7 @@ plugins {
   id("java-library")
 }
 
-version = "1.0.0"
+version = "1.0.1"
 
 java {
   sourceCompatibility = JavaVersion.VERSION_16

src/main/java/technology/sola/json/JsonArray.java

@@ -10,6 +10,10 @@ public JsonArray(int initialCapacity) {
     super(initialCapacity);
   }
 
+  public JsonElement asElement() {
+    return new JsonElement(this);
+  }
+
   public JsonObject getObject(int index) {
     return get(index).asObject();
   }
@@ -49,13 +53,13 @@ public boolean isNull(int index) {
   public boolean add(JsonObject value) {
     if (value == null) return addNull();
 
-    return add(new JsonElement(value));
+    return add(value.asElement());
   }
 
   public boolean add(JsonArray value) {
     if (value == null) return addNull();
 
-    return add(new JsonElement(value));
+    return add(value.asElement());
   }
 
   public boolean add(String value) {

src/main/java/technology/sola/json/JsonElement.java

@@ -1,5 +1,7 @@
 package technology.sola.json;
 
+import technology.sola.json.exception.JsonElementTypeException;
+
 public class JsonElement {
   private final JsonValueType type;
   private Object value;
@@ -54,7 +56,8 @@ public boolean asBoolean() {
   }
 
   public int asInt() {
-    return (int) asLong();
+    assertType(JsonValueType.LONG);
+    return ((Number) this.value).intValue();
   }
 
   public long asLong() {
@@ -63,7 +66,8 @@ public long asLong() {
   }
 
   public float asFloat() {
-    return (float) asDouble();
+    assertType(JsonValueType.DOUBLE);
+    return ((Number) this.value).floatValue();
   }
 
   public double asDouble() {
@@ -101,7 +105,7 @@ public String toString() {
 
   private void assertType(JsonValueType assertionType) {
     if (type != assertionType) {
-      throw new RuntimeException("Json value is not of desired type");
+      throw new JsonElementTypeException(assertionType.name(), type.name());
     }
   }
 

src/main/java/technology/sola/json/JsonMapper.java

@@ -0,0 +1,46 @@
+package technology.sola.json;
+
+import java.util.List;
+
+public interface JsonMapper<T> {
+  /**
+   * Converts object of type T into a {@link JsonObject}.
+   *
+   * @param object  the object to convert
+   * @return the {@code JsonObject} representing the converted object
+   */
+  JsonObject toJson(T object);
+
+  /**
+   * Converts a {@link List} of T into a {@link JsonArray}.
+   *
+   * @param list the {@code List} to convert
+   * @return the converted {@code JsonArray}
+   */
+  default JsonArray toJson(List<T> list) {
+    JsonArray jsonArray = new JsonArray(list.size());
+
+    list.forEach(item -> jsonArray.add(toJson(item)));
+
+    return jsonArray;
+  }
+
+  /**
+   * Converts a {@link JsonObject} into an object of type T.
+   *
+   * @param jsonObject  the {@code JsonObject} to convert
+   * @return the converted object of type T
+   */
+  T toObject(JsonObject jsonObject);
+
+  /**
+   * Converts a {@link JsonArray} into a {@link List} of desired type T. This assumes that each child of {@code jsonArray}
+   * is a {@link JsonObject} and of type T.
+   *
+   * @param jsonArray  the {@code JsonArray} to convert
+   * @return the converted {@code List<T>}
+   */
+  default List<T> toList(JsonArray jsonArray) {
+    return jsonArray.stream().map(item -> toObject(item.asObject())).toList();
+  }
+}

src/main/java/technology/sola/json/JsonObject.java

@@ -12,6 +12,10 @@ public JsonObject(int initialCapacity) {
     super(initialCapacity);
   }
 
+  public JsonElement asElement() {
+    return new JsonElement(this);
+  }
+
   public JsonObject getObject(String key) {
     return get(key).asObject();
   }
@@ -32,7 +36,7 @@ public float getFloat(String key) {
     return get(key).asFloat();
   }
 
-  public double getInt(String key) {
+  public int getInt(String key) {
     return get(key).asInt();
   }
 
@@ -61,13 +65,13 @@ public JsonElement get(String key) {
   public JsonElement put(String key, JsonObject value) {
     if (value == null) return putNull(key);
 
-    return put(key, new JsonElement(value));
+    return put(key, value.asElement());
   }
 
   public JsonElement put(String key, JsonArray value) {
     if (value == null) return putNull(key);
 
-    return put(key, new JsonElement(value));
+    return put(key, value.asElement());
   }
 
   public JsonElement put(String key, String value) {

src/main/java/technology/sola/json/SolaJson.java

@@ -5,6 +5,8 @@
 import technology.sola.json.parser.Parser;
 import technology.sola.json.token.Tokenizer;
 
+import java.util.List;
+
 /**
  * SolaJson contains methods for parsing strings into {@link JsonElement}s and serializing {@code JsonElement}s into strings.
  */
@@ -23,6 +25,30 @@ public JsonElement parse(String jsonString) {
     return visit(root);
   }
 
+  /**
+   * Parses a JSON string into an object of type T using a {@link JsonMapper}.
+   *
+   * @param jsonString  the JSON string to parse
+   * @param jsonMapper  the {@code JsonMapper} to use during conversion
+   * @param <T>  the type of the object to convert to
+   * @return the converted Java object of type T
+   */
+  public <T> T parse(String jsonString, JsonMapper<T> jsonMapper) {
+    return jsonMapper.toObject(parse(jsonString).asObject());
+  }
+
+  /**
+   * Parses a JSON string into a {@link List} of type T using a {@link JsonMapper}.
+   *
+   * @param jsonString  the JSON string to parse
+   * @param jsonMapper  the {@code JsonMapper} to use during conversion
+   * @param <T>  the type of the object to convert to
+   * @return the converted List of Java object of type T
+   */
+  public <T> List<T> parseList(String jsonString, JsonMapper<T> jsonMapper) {
+    return jsonMapper.toList(parse(jsonString).asArray());
+  }
+
   /**
    * Serializes as {@link JsonElement}.
    *
@@ -53,6 +79,30 @@ public String serialize(JsonArray jsonArray) {
     return jsonArray.toString();
   }
 
+  /**
+   * Serializes an object of type T to a string using a {@link JsonMapper}.
+   *
+   * @param object  the object to serialize
+   * @param jsonMapper  the {@code JsonMapper} to use during conversion
+   * @param <T>  the type of the object to serialize
+   * @return serialized JSON string
+   */
+  public <T> String serialize(T object, JsonMapper<T> jsonMapper) {
+    return serialize(jsonMapper.toJson(object));
+  }
+
+  /**
+   * Serializes a list of objects of type T to a string using a {@link JsonMapper}.
+   *
+   * @param list  the list of objects to serialize
+   * @param jsonMapper  the {@code JsonMapper} to use during conversion
+   * @param <T>  the type of the object to serialize
+   * @return serialized JSON string
+   */
+  public <T> String serializeList(List<T> list, JsonMapper<T> jsonMapper) {
+    return serialize(jsonMapper.toJson(list));
+  }
+
   private JsonElement visit(AstNode astNode) {
     return switch (astNode.type()) {
       case OBJECT -> visitObject(astNode);

src/main/java/technology/sola/json/exception/JsonElementTypeException.java

@@ -0,0 +1,7 @@
+package technology.sola.json.exception;
+
+public class JsonElementTypeException extends RuntimeException {
+  public JsonElementTypeException(String desiredType, String actualType) {
+    super(String.format("JsonElement type is [%s] but attempted to use as [%s]", actualType, desiredType));
+  }
+}

src/test/java/technology/sola/json/JsonArrayTest.java

@@ -0,0 +1,114 @@
+package technology.sola.json;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class JsonArrayTest {
+  private JsonArray root;
+
+  @BeforeEach
+  void setup() {
+    root = new JsonArray();
+  }
+
+  @Nested
+  class convenience {
+    @Test
+    void objectMethods() {
+      JsonObject expected = new JsonObject();
+
+      root.add(expected);
+      assertEquals(expected, root.getObject(0));
+
+      root.add((JsonObject) null);
+      assertTrue(root.isNull(1));
+    }
+
+    @Test
+    void arrayMethods() {
+      JsonArray expected = new JsonArray();
+
+      root.add(expected);
+      assertEquals(expected, root.getArray(0));
+
+      root.add((JsonArray) null);
+      assertTrue(root.isNull(1));
+    }
+
+    @Test
+    void stringMethods() {
+      String expected = "";
+
+      root.add(expected);
+      assertEquals(expected, root.getString(0));
+
+      root.add((String) null);
+      assertTrue(root.isNull(1));
+    }
+
+    @Test
+    void doubleMethods() {
+      double expected = 0.0;
+
+      root.add(expected);
+      assertEquals(expected, root.getDouble(0));
+
+      root.add((Double) null);
+      assertTrue(root.isNull(1));
+    }
+
+    @Test
+    void floatMethods() {
+      float expected = 0.0f;
+
+      root.add(expected);
+      assertEquals(expected, root.getFloat(0));
+
+      root.add((Float) null);
+      assertTrue(root.isNull(1));
+    }
+
+    @Test
+    void longMethods() {
+      long expected = 0L;
+
+      root.add(expected);
+      assertEquals(expected, root.getLong(0));
+
+      root.add((Long) null);
+      assertTrue(root.isNull(1));
+    }
+
+    @Test
+    void intMethods() {
+      int expected = 0;
+
+      root.add(expected);
+      assertEquals(expected, root.getInt(0));
+
+      root.add((Integer) null);
+      assertTrue(root.isNull(1));
+    }
+
+    @Test
+    void booleanMethods() {
+      boolean expected = true;
+
+      root.add(expected);
+      assertEquals(expected, root.getBoolean(0));
+
+      root.add((Boolean) null);
+      assertTrue(root.isNull(1));
+    }
+
+    @Test
+    void nullMethods() {
+      root.addNull();
+      assertTrue(root.isNull(0));
+    }
+  }
+}

src/test/java/technology/sola/json/JsonElementTest.java

@@ -0,0 +1,15 @@
+package technology.sola.json;
+
+import org.junit.jupiter.api.Test;
+import technology.sola.json.exception.JsonElementTypeException;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+class JsonElementTest {
+  @Test
+  void whenAccessingIncorrectType_shouldThrowException() {
+    JsonElement jsonElement = new JsonElement();
+
+    assertThrows(JsonElementTypeException.class, jsonElement::asArray);
+  }
+}