Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

public class Main {
    private static final String EMPTY_STRING = "";

    /**
     * Convenience method. Redirects to parseNodesFromXml(String xmlString, String nodeName, String trimString), passing empty string as trimString
     * 
     * @param xmlString
     * @param nodeName
     * @return
     */
    public static List<String> parseNodesFromXml(String xmlString, String nodeName) {
        return parseNodesFromXml(xmlString, nodeName, EMPTY_STRING);
    }

    /**
     * DOM Parser method. 
     * Converts the input xmlString into List<String> of all the text in the nodes named nodeName.
     * The memory footprint is small enough when we deal with less than 200 tweets.
     * 
     * @param xmlString
     *            The xml string
     * @param nodeName
     *            the name of the node, we are intersted in (e.g. "text")
     * @param trimString
     *            if we want to trim a particular pattern from every node's text, we pass it as trimString, e.g. "(https?://[^\\s]+)"
     * @return List of all the text strings from every node named nodeName. trimString text is trimmed from the result strings.
     */
    public static List<String> parseNodesFromXml(String xmlString, String nodeName, String trimString) {
        List<String> nodeTexts = new ArrayList<String>();

        try {
            DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
            InputSource inputSource = new InputSource();
            inputSource.setCharacterStream(new StringReader(xmlString));

            try {
                Document document = db.parse(inputSource);
                NodeList nodes = document.getElementsByTagName(nodeName);
                for (int i = 0; i < nodes.getLength(); i++) {
                    String nodeText = nodes.item(i).getTextContent();
                    String trimmedNodeText = trimStringFromText(trimString, nodeText);
                    nodeTexts.add(trimmedNodeText);
                }

            } catch (SAXException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        }

        return nodeTexts;
    }

    /**
     * Helper method trimming the trimString pattern from the text input parameter
     * 
     * @param trimString
     *            regex pattern
     * @param text
     *            text to be cleaned
     * @return the input text with any occurrences of the trimString pattern removed.
     */
    private static String trimStringFromText(String trimString, String text) {
        if (trimString != EMPTY_STRING) {
            Pattern trimPattern = Pattern.compile(trimString);
            Matcher matcher = trimPattern.matcher(text);

            while (matcher.find()) {
                // System.out.println(matcher.group());
                text = text.replace(matcher.group(), EMPTY_STRING);
            }
        }
        return text;
    }
}