Fixed bug with null values, since stacks should not allow null

Author: Antonio Sanchez

src/main/java/org/json/simple/parser/ContainerContentHandler.java

@@ -18,6 +18,8 @@ private enum ContainerType {
 		ARRAY
 	}
 
+	private static Object NULL_VALUE = new Object();
+	
 	ArrayDeque<Object> valueStack;
 	ArrayDeque<ContainerType> containerStack;
 	ContainerFactory factory;
@@ -27,10 +29,14 @@ public ContainerContentHandler(ContainerFactory factory) {
 	}
 
 	public Object getContent() {
+	    Object val = null;
 		if (valueStack.size() > 0) {
-			return valueStack.pop();
+			val = valueStack.pop();
+			if (val == NULL_VALUE) {
+			    return null;
+			}
 		}
-		return null;
+		return val;
 	}
 
 	public int getContentSize() {
@@ -132,6 +138,9 @@ public boolean endObjectEntry() throws ParseException, IOException {
 		}
 
 		Object value = valueStack.pop();
+		if (value == NULL_VALUE) {
+		    value = null;
+		}
 		String key = (String) valueStack.pop();
 		@SuppressWarnings("rawtypes")
 		// XXX raw types unavoidable do to the way ContainerFactory is currently written
@@ -186,6 +195,9 @@ public boolean primitive(Object value) throws ParseException, IOException {
 			List array = (List) (valueStack.peek());
 			array.add(value);
 		} else {
+		    if (value == null) {
+		        value = NULL_VALUE;
+		    }
 			valueStack.push(value);
 		}
 

src/main/java/org/json/simple/parser/DefaultContentHandler.java

@@ -17,17 +17,25 @@ private enum ContainerType {
 		ARRAY
 	}
 
+	// special identifier for null value to allow it to be added to the stack
+	static final Object NULL_VALUE = new Object();
+	
 	ArrayDeque<Object> valueStack;
 	ArrayDeque<ContainerType> containerStack;
 
 	public DefaultContentHandler() {
 	}
 
 	public Object getContent() {
+	    Object val = null;
 		if (valueStack.size() > 0) {
-			return valueStack.pop();
+		    val = valueStack.pop();
+		    if (val == NULL_VALUE) {
+		        return null;
+		    }
+		    
 		}
-		return null;
+		return val;
 	}
 
 	public int getContentSize() {
@@ -113,6 +121,9 @@ public boolean endObjectEntry() throws ParseException, IOException {
 		}
 
 		Object value = valueStack.pop();
+		if (value == NULL_VALUE) {
+		    value = null;
+		}
 		String key = (String) valueStack.pop();
 		@SuppressWarnings("rawtypes")
 		// XXX raw types unavoidable do to the way ContainerFactory is currently written
@@ -167,6 +178,9 @@ public boolean primitive(Object value) throws ParseException, IOException {
 			List array = (List) (valueStack.peek());
 			array.add(value);
 		} else {
+		    if (value == null) {
+		        value = NULL_VALUE;
+		    }
 			valueStack.push(value);
 		}
 

src/test/java/org/json/simple/JSONEmptyAndNullTest.java

@@ -0,0 +1,72 @@
+package org.json.simple;
+
+import org.json.simple.JSONArray;
+import org.json.simple.JSONObject;
+import org.json.simple.parser.JSONParser;
+import org.json.simple.parser.ParseException;
+
+import org.junit.Assert;
+import org.junit.Test;
+import junit.framework.TestCase;
+
+public class JSONEmptyAndNullTest extends TestCase {
+    
+    public void testNullValue() throws ParseException  {
+        String str = "null";
+        JSONParser parser = new JSONParser();
+        Object obj = parser.parse(str);
+        Object sol = null;
+        Assert.assertEquals("null value", sol,  obj);
+    }
+    
+    public void testNullValueInObject() throws ParseException  {
+        String str = "{\"exception\":null,\"status\":\"ERROR\"}";
+        JSONParser parser = new JSONParser();
+        Object obj = parser.parse(str);
+        JSONObject sol = new JSONObject();
+        sol.put("exception", null);
+        sol.put("status", "ERROR");
+        Assert.assertEquals("null value in JSON object", sol,  obj);
+    }
+    
+    public void testNullValueInArray() throws ParseException {
+        String str = "{\"list\": [null,\"hello\", null, \"world\"]}";
+        JSONParser parser = new JSONParser();
+        Object obj = parser.parse(str);
+        
+        JSONArray array = new JSONArray();
+        array.add(null);
+        array.add("hello");
+        array.add(null);
+        array.add("world");
+        JSONObject sol = new JSONObject();
+        sol.put("list", array);
+        
+        Assert.assertEquals("null value in JSON array", sol,  obj);
+    }
+    
+    public void testEmptyArray() throws ParseException {
+        JSONParser parser = new JSONParser();
+        String arrayStr = "[]";
+        JSONArray array = (JSONArray)(parser.parse(arrayStr));
+        JSONArray sol = new JSONArray();
+        Assert.assertEquals("Empty array", sol, array );
+    }
+    
+    public void testEmptyObject() throws ParseException {
+        JSONParser parser = new JSONParser();
+        String objStr = "{}";
+        JSONObject obj = (JSONObject)(parser.parse(objStr));
+        JSONObject sol = new JSONObject();
+        Assert.assertEquals("Empty object", sol, obj );
+    }
+    
+    public void testEmptyString() throws ParseException {
+        JSONParser parser = new JSONParser();
+        String objStr = "";
+        Object obj = parser.parse(objStr);
+        JSONObject sol = null;
+        Assert.assertEquals("Empty object", sol, obj );
+    }
+
+}

src/test/java/org/json/simple/Test.java

@@ -25,9 +25,9 @@
  * @author FangYidong<[email protected]>
  */
 @SuppressWarnings("deprecation")
-public class Test extends TestCase{
+public class Test extends TestCase {
 
-	public void testDecode() throws Exception{
+	public void testDecode() throws Exception {
 		System.out.println("=======decode=======");
 
 		String s="[0,{\"1\":{\"2\":{\"3\":{\"4\":[5,{\"6\":7}]}}}}]";
@@ -192,7 +192,7 @@ public boolean startObjectEntry(String key) throws ParseException {
 			pe.printStackTrace();
 		}
 
-        class KeyFinder implements ContentHandler{
+        class KeyFinder implements ContentHandler {
             private Object value;
             private boolean found = false;
             private boolean end = false;