Example code of how NOT to use redundant Map whenr generating ast tree JSON

gistfile1.java

public static String toJson(DetailAST ast) throws IOException {

		int nodeId = ROOT_NODE_ID;
		Stack<Integer> parentNodeIdStack = new Stack<>();
		parentNodeIdStack.push(nodeId); // root node id

		DetailAST currentNode = ast;

		StringWriter writer = new StringWriter();
		JsonGenerator jsonGenerator = JSON_FACTORY.createJsonGenerator(writer).useDefaultPrettyPrinter();

		jsonGenerator.writeStartObject();

		while (currentNode != null) {

			DetailAST toVisit = currentNode.getFirstChild();
			nodeId++;

			jsonGenerator.writeObjectFieldStart(currentNode.toString());
			jsonGenerator.writeStringField("text", currentNode.getText());
			jsonGenerator.writeStringField("type", TokenTypes.getTokenName(currentNode.getType()));
			jsonGenerator.writeNumberField("lineNo", currentNode.getLineNo());
			jsonGenerator.writeNumberField("columnNo", currentNode.getColumnNo());
			jsonGenerator.writeNumberField("id", nodeId);
			jsonGenerator.writeNumberField("parentId", parentNodeIdStack.peek());
			jsonGenerator.writeEndObject();

			if (toVisit != null) {
				parentNodeIdStack.push(nodeId);
			}

			while ((currentNode != null) && (toVisit == null)) {
				toVisit = currentNode.getNextSibling();
				if (toVisit == null) {
					currentNode = currentNode.getParent();
					parentNodeIdStack.pop();
				}
			}
			currentNode = toVisit;
		}

		jsonGenerator.writeEndObject();
		jsonGenerator.close();

		String result = writer.toString();
		writer.close();

		parentNodeIdStack = null;

		return result;
	}