How to Prevent Repeated Instantiation of InputSource with XPath in Java

How can I avoid repeatedly instantiating InputSource when using XPath in Java?

InputSource inputSource = new InputSource(new StringReader(xmlString));
XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xpath = xPathFactory.newXPath();
String expression = "//element";
NodeList resultNodes = (NodeList) xpath.evaluate(expression, inputSource, XPathConstants.NODESET);

When working with XPath in Java, repeatedly instantiating the InputSource can lead to unnecessary overhead and performance degradation. By reusing the InputSource or using a more efficient initialization technique, you can streamline your XML processing. This ensures that your application runs smoothly, especially when dealing with larger XML documents or multiple XPath evaluations.

// Sample code showcasing reuse of InputSource
InputSource inputSource = new InputSource(new StringReader(xmlString));
XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xpath = xPathFactory.newXPath();
String expression1 = "//firstElement";
NodeList resultNodes1 = (NodeList) xpath.evaluate(expression1, inputSource, XPathConstants.NODESET);
String expression2 = "//secondElement";
NodeList resultNodes2 = (NodeList) xpath.evaluate(expression2, inputSource, XPathConstants.NODESET);

Causes

• Creating a new InputSource instance for each XPath evaluation increases memory usage.
• Repeated instantiation can lead to performance bottlenecks in applications processing large XML files.

Solutions

• Reuse the InputSource instance wherever possible to avoid repeated creation.
• Consider using a caching mechanism to store InputSource instances if the same XML source is evaluated multiple times.

Mistake: Instantiating a new InputSource for each XPath expression evaluation.

Solution: Instantiate the InputSource once and reuse it for multiple XPath evaluations.

Mistake: Not closing resources properly when using InputSource.

Solution: Ensure that all resources (like streams) are properly closed to avoid memory leaks.