Fibonacci Shell Script

Here is a quick unix shell script which prints out the Fibonacci sequence:

0,1,1,2,3,5,8,13,21,34,55,89,144,...

The first two Fibonacci numbers are 0 and 1, and each remaining number is the sum of the previous two.

#!/bin/sh
prev=0
next=1

echo $prev

while(true)
do
 echo $next

 #add the two numbers
 sum=$(($prev+$next))

 #swap
 prev=$next
 next=$sum
 sleep 1
done

Using XPath in Java

Given the following xml document:

<hosts>
  <host name="starship" port="8080"/>
  <host name="firefly" port="8180"/>
</hosts>

this is how you can use the javax.xml.xpath library to run an XPath query in order to obtain a list of host names:

//create a document
DocumentBuilderFactory domFactory = 
                     DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse("file.xml");

//create the xpath expression
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();
XPathExpression expr = xpath.compile("//host/@name");

//run the xpath query
Object result = expr.evaluate(doc, XPathConstants.NODESET);

//read results
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
    System.out.println(nodes.item(i).getNodeValue());
}