Trouble parsing xml in large Inputstream

Question

I am running a query through an API and I'm receiving a larger set of XML through an InputStream than I normally expect. This is causing me to run into heap space errors while trying to parse the XML into a String. Here is how I am currently parsing the input stream:

public String parseXml(InputStream inputStream) throws IOException {
    String myString;
    List<String> matchingXmlList = new ArrayList<>();
    byte[] byteArray = toByteArray(inputStream);
    String tempString = new String(byteArray, StandardCharsets.UTF_8);
    return tempString;
}

Under normal circumstances, this is the output:

<?xml version="1.0" encoding="UTF-8">
  <queryResult>
    <records />
    <records />
    <records />
    <records />
  </queryResult>

After receiving an output like this, I then use a Matcher to parse each individual records node and add it to a List of Strings. But when the InputStream is too large, I run into memory problems when trying to put the InputStream into a String.

Is there a way to parse the InputStream without running into memory problems? I need to be able to parse each individual records element to a string of XML.

codeCompiler77 codeCompiler77 · Accepted Answer · 2016-03-02T04:18:02

You have two choices, use an XML library like JAXB or accept bytes at a time. You're creating overflow so read in 1024 bytes at a time until the end of the file :)

Also are you have trying reading the file or assigning values after you read it? For large strings, use StringBuilder

Trouble parsing xml in large Inputstream

1 Answers