Merge pull request #1 from stevenlagoy/stronger-typing

Stronger typing

Author: stevenlagoy

README.md

@@ -19,7 +19,7 @@ Add this dependency to your `pom.xml`:
 <dependency>
     <groupId>com.github.stevenlagoy</groupId>
     <artifactId>json-java-objectifier</artifactId>
-    <version>1.0.4</version>
+    <version>1.0.5</version>
 </dependency>
 ```
 

pom.xml

@@ -4,7 +4,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.github.stevenlagoy</groupId>
     <artifactId>json-java-objectifier</artifactId>
-    <version>1.0.4</version>
+    <version>1.0.5</version>
     <packaging>jar</packaging>
     <name>JSON Java Objectifier</name>
     <description>Java tools for converting JSON into typed object structures</description>

src/main/java/core/JSONObject.java

@@ -3,7 +3,6 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
-import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 
 /**
  * A JSONObject is a custom data structure that represents a JSON object. It supports nested key-value pairs, arrays (as
@@ -57,6 +56,7 @@ public class JSONObject implements Iterable<Object> {
      */
     private static boolean isValidJsonType(Object value) {
         return (
+            value == null ||
             value instanceof String ||
             value instanceof Number ||
             value instanceof JSONObject ||
@@ -94,10 +94,8 @@ public JSONObject(String key) {
     /**
      * Create a {@code JSONObject} with the given key and value.
      *
-     * @param key
-     *            A {@code String} key
-     * @param value
-     *            A valid JSON value
+     * @param key Valid {@code String} key for JSON Object
+     * @param value Valid JSON value ({@code String}, {@code Number}, {@code JSONObject}, {@code List<>}, {@code Boolean}, {@code Object extends Jsonic})
      */
     public JSONObject(String key, Object value) {
         if (!isValidJsonType(value)) {
@@ -107,11 +105,12 @@ public JSONObject(String key, Object value) {
         this.value = value;
         if (value == null)
             type = null;
-        else if (value instanceof List<?>)
+        else if (value instanceof List<?>) {
             if (isJSONList(getAsList()))
                 type = JSONObject.class;
             else
                 type = ArrayList.class;
+        }
         else
             type = value.getClass();
     }
@@ -144,46 +143,51 @@ public Object getValue() {
     /**
      * Return the value as the given class.
      *
-     * @param clazz
-     *            An existant class to cast this object's value into.
+     * @param clazz Existant class to cast this object's value into.
      *
-     * @return The value as a type of the given class, or null if uncastable.
+     * @return Value as a type of the given class.
+     * @throws ClassCastException if the value is not null and is not assignable to the type T.
      */
-    public <T> T getValueAs(Class<T> clazz) {
-        try {
-            return clazz.cast(value);
-        } catch (ClassCastException e) {
-            e.printStackTrace();
-            return null;
-        }
+    public <T> T getValueAs(Class<T> clazz) throws ClassCastException {
+        return clazz.cast(value);
     }
 
+    /** Returns the value of this JSONObject as a String, or throws a ClassCastException if unable. */
     public String getAsString() {
-        return value instanceof String ? (String) value : null;
+        if (value instanceof String) return (String) value;
+        else throw new ClassCastException("Cannot cast non-String value to String.");
     }
 
+    /** Returns the value of this JSONObject as a Number, or throws a ClassCastException if unable. */
     public Number getAsNumber() {
-        return value instanceof Number ? (Number) value : null;
+        if (value instanceof Number) return (Number) value;
+        else throw new ClassCastException("Cannot cast non-Number value to Number.");
     }
 
-    @SuppressFBWarnings("NP_BOOLEAN_RETURN_NULL")
+    /** Returns the value of this JSONObject as a Boolean, or throws a ClassCastException if unable. */
     public Boolean getAsBoolean() {
-        return value instanceof Boolean ? (Boolean) value : null;
+        if (value instanceof Boolean) return (Boolean) value;
+        else throw new ClassCastException("Cannot cast non-Boolean value to Boolean.");
     }
 
+    /** Returns the value of this JSONObject as another JSONObject, or {@code null} if unable. */
     public JSONObject getAsObject() {
 
-        if (value instanceof JSONObject) return (JSONObject) value;
+        return this;
 
-        if (value instanceof List<?> && type.equals(JSONObject.class)) {
-            return this;
-        }
+        // if (value instanceof JSONObject) return (JSONObject) value;
 
-        return null;
+        // if (value instanceof List<?> && type.equals(JSONObject.class)) {
+        //     return this;
+        // }
+
+        // return null;
     }
 
+    /** Returns the value of this JSONObject as a List, or throws a ClassCastException if unable. */
     public List<?> getAsList() {
-        return value instanceof List<?> ? (List<?>) value : null;
+        if (value instanceof List<?>) return (List<?>) value;
+        else throw new ClassCastException("Cannot cast non-List value to List.");
     }
 
     public void setValue(Object value) {
@@ -226,10 +230,9 @@ public Class<? extends Object> getType() {
      * Search the JSONObject tree structure for a JSONObject with the given key, and return the value of that
      * JSONObject.
      *
-     * @param key
-     *            A String key to search for within the tree structure.
+     * @param key String key to search for within the tree structure.
      *
-     * @return The value of the JSONObject with the given key, or null if unfound.
+     * @return Value of the JSONObject with the given key, or null if unfound.
      */
     public Object get(String key) {
         if (this.key.equals(key))
@@ -253,7 +256,7 @@ public Object get(String key) {
     /**
      * Get the native type of the inner value of this JSONObject.
      *
-     * @return The class of the value (String, Number, JSONObject, List<?>, Boolean, or null)
+     * @return Class of the value (String, Number, JSONObject, List<?>, Boolean, or null)
      */
     public Class<?> getInnerType() {
         return value.getClass();
@@ -265,8 +268,7 @@ public Class<?> getInnerType() {
      * Traverse the tree structure of this JSONObject inorder and return an indexable list of the objects' values. Start
      * with the leftmost value, then the root value, then the rightmost value, recursively.
      *
-     * @param result
-     *            A List<Object> to be populated with the values from the inorder traversal.
+     * @param result List<Object> to be populated with the values from the inorder traversal.
      */
     public void inorderTraversal(List<Object> result) {
         if (value == null) {
@@ -297,12 +299,10 @@ public Iterator<Object> iterator() {
     // Stringify methods
 
     /**
-     * Turn this JSONObject into a String representation. Should result in a functionally identical String to the JSON
-     * object which was read to create this JSONObject.
-     *
-     * @return The String representation of this JSONObject
+     * Turn this JSONObject into a String representation. Will result in a functionally identical String to the theoretical JSON
+     * file which was parsed to create this JSONObject.
      *
-     * @see JSONObject#toString(int)
+     * @return String representation of this JSONObject
      */
     @Override
     public String toString() {
@@ -317,8 +317,7 @@ public int hashCode() {
     /**
      * Determine whether this JSONObect is equal to the other JSONObject by comparing their String representations.
      *
-     * @param other
-     *            A JSONObject with which to compare this JSONObject
+     * @param other JSONObject with which to compare this JSONObject
      *
      * @return True if the String representations are the same, False otherwise
      *

src/main/java/core/JSONStringifier.java

@@ -42,14 +42,14 @@ public static String stringifyJson(JSONObject json) {
     public static String stringifyValue(Object value, Class<?> type) {
         if (type.equals(JSONObject.class)) {
             @SuppressWarnings("unchecked") // The type of this object is known from the type parameter
-            ArrayList<JSONObject> objects = (ArrayList<JSONObject>) value;
+            List<JSONObject> objects = (List<JSONObject>) value;
             StringBuilder result = new StringBuilder();
             for (JSONObject object : objects)
                 result.append(stringifyObject(object));
             return result.toString();
         }
         if (type.equals(ArrayList.class)) {
-            return stringifyArray((ArrayList<?>) value);
+            return stringifyArray((List<?>) value);
         }
         return stringifyValue(value);
     }
@@ -74,9 +74,9 @@ public static String stringifyObject(JSONObject object) {
 
         if (value == null)
             sb.append("null");
-        else if (type != null && type.equals(JSONObject.class)) {
+        else if (type != null && type.equals(JSONObject.class) && value instanceof List) {
             @SuppressWarnings("unchecked")
-            List<JSONObject> objects = (ArrayList<JSONObject>) value;
+            List<JSONObject> objects = (List<JSONObject>) value;
             sb.append("{");
             for (int i = 0; i < objects.size(); i++) {
                 String nested = stringifyObject(objects.get(i));
@@ -85,6 +85,11 @@ else if (type != null && type.equals(JSONObject.class)) {
             }
             sb.append("}");
         }
+        else if (type != null && value instanceof JSONObject json) {
+            sb.append("{");
+            sb.append(json.toString());
+            sb.append("}");
+        }
         else if (type != null)
             sb.append(stringifyValue(value, type));
         else

src/main/java/core/Jsonic.java

@@ -0,0 +1,154 @@
+package core;
+
+import java.lang.reflect.Array;
+import java.lang.reflect.Modifier;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+/**
+ * Interface allowing Json methods to be used to create and store JSONObjects
+ * representing instances of classes which implement this interface.
+ * <p>
+ * <b> Example Usage: </b>
+ * <p>
+ * <code> class MyClass implements Jsonic&lt;MyClass&gt; { ... } </code>
+ * @param <T> The type of the object implementing this interface (should be the same as the Class Name).
+ */
+public interface Jsonic<T extends Jsonic<T>> {
+
+    /**
+     * Turn this object's fields into an accurately-modeled JSONObject.
+     * @return A JSONObject representing this object.
+     */
+    public JSONObject toJson();
+
+    /**
+     * Interpret a JSONObject into an object of this type.
+     * @param json A JSONObject containing any number of the fields for this object as key-value pairs.
+     * @return The Object interpreted from the Json. Note that this object's fields will also be set.
+     */
+    public T fromJson(JSONObject json);
+
+    /**
+     * Turns a collection into a JSONObject list. Any elements which extend Jsonic<> will use their {@code .toJson()} methods,
+     *      and any other not-null elements will be passed to the {@code Jsonic.toJson(Object)} function.
+     * @param collection Collection containing any type.
+     * @return List of JSONObjects with the contents of the passed collection.
+     * @see #toJson()
+     * @see #toJson(Object)
+     */
+    public static List<JSONObject> collectionToJson(Collection<?> collection) {
+        List<JSONObject> json = new ArrayList<>();
+        for (Object item : collection) {
+            if (item instanceof Jsonic<?> jsonic) {
+                json.add(jsonic.toJson());
+            }
+            else if (item != null) {
+                json.add(toJson(item));
+            }
+            else json.add(new JSONObject()); // empty object representing null
+        }
+        return json;
+    }
+
+    /**
+     * Turns an array into a JSONObject list. Any elements which extend Jsonic<> will use their {@code .toJson()} methods,
+     *      and any other not-null elements will be passed to the {@code Jsonic.toJson(Object)} function.
+     * @param array Array containing any type.
+     * @return List of JSONObjects with the contents of the passed array.
+     * @see #toJson()
+     * @see #toJson(Object)
+     */
+    public static List<JSONObject> arrayToJson(Object array) {
+        int length = Array.getLength(array);
+        List<JSONObject> json = new ArrayList<>();
+        for (int i = 0; i < length; i++) {
+            Object element = Array.get(array, i);
+            if (element instanceof Jsonic<?> jsonic) {
+                json.add(jsonic.toJson());
+            }
+            else if (element != null) {
+                json.add(toJson(element));
+            }
+        }
+        return json;
+    }
+
+    private static boolean isPrimitiveOrWrapper(Class<?> type) {
+        Class<?>[] types = {Boolean.class, Byte.class, Character.class, Short.class, Integer.class, Long.class, Float.class, Double.class, String.class};
+        if (type.isPrimitive()) return true;
+        for (Class<?> t : types) {
+            if (type == t) return true;
+        }
+        return false;
+    }
+
+    /**
+     * Reflects the passed Class's fields into an unvalued "template" JSONObject.
+     * @param clazz Any class.
+     * @return A JSONObject "template" of the class's fields.
+     * @see #toJson(Object)
+     */
+    public static JSONObject classJson(Class<? extends Object> clazz) {
+        List<JSONObject> fields = new ArrayList<>();
+        for (java.lang.reflect.Field f : clazz.getDeclaredFields()) {
+            // Only take public, non-static fields
+            int modifiers = f.getModifiers();
+            if (Modifier.isPublic(modifiers) && !Modifier.isStatic(modifiers)) {
+                String field = f.getName();
+                fields.add(new JSONObject(field));
+            }
+        }
+        return new JSONObject(clazz.getSimpleName(), fields);
+    }
+
+    /**
+     * Reflects the passed Object's public instance fields and their values into a JSONObject.
+     * @param o Object of any type.
+     * @return JSONObject containing the passed object's fields and their values.
+     * @see #classJson(Class)
+     */
+    public static JSONObject toJson(Object o) {
+        List<JSONObject> fields = new ArrayList<>();
+        Class<?> clazz = o.getClass();
+
+        // Get all fields declared by O.class
+        for (java.lang.reflect.Field f : clazz.getDeclaredFields()) {
+            // Only take public, non-static fields
+            int modifiers = f.getModifiers();
+            if (Modifier.isPublic(modifiers) && !Modifier.isStatic(modifiers)) {
+                Object value;
+                try {
+                    value = f.get(o);
+                }
+                catch (IllegalArgumentException e) {
+                    e.printStackTrace();
+                    continue;
+                }
+                catch (IllegalAccessException e) {
+                    e.printStackTrace();
+                    continue;
+                }
+
+                if (value instanceof Jsonic<?> jsonic) {
+                    fields.add(new JSONObject(f.getName(), jsonic.toJson()));
+                }
+                else if (value != null && isPrimitiveOrWrapper(value.getClass())) {
+                    fields.add(new JSONObject(f.getName(), value));
+                }
+                else if (value != null && value.getClass().isArray()) {
+                    fields.add(new JSONObject(f.getName(), arrayToJson(value)));
+                }
+                else if (value != null && value instanceof Collection<?> collection) {
+                    fields.add(new JSONObject(f.getName(), collectionToJson(collection)));
+                }
+                else if (value != null) {
+                    fields.add(new JSONObject(f.getName(), toJson(value)));
+                }
+                else fields.add(new JSONObject(f.getName(), null));
+            }
+        }
+        return new JSONObject(o.getClass().getSimpleName(), fields);
+    }
+}