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Remove HTML tags from a file to extract only the TEXTTag(s): IO String/Number Networking


Using regular expression
A special regular expression is used to strip out anything between a < and > . 
import java.io.*;

public class Html2TextWithRegExp {
   private Html2TextWithRegExp() {}

   public static void main (String[] args) throws Exception{
     StringBuilder sb = new StringBuilder();
     BufferedReader br = new BufferedReader(new FileReader("java-new.html"));
     String line;
     while ( (line=br.readLine()) != null) {
       sb.append(line);
       // or
       //  sb.append(line).append(System.getProperty("line.separator"));
     }
     String nohtml = sb.toString().replaceAll("\\<.*?>","");
     System.out.println(nohtml);
   }
}
However if any Javascript is present, the script will be seen as text. Also you may need to add some logic during the reading to take into account only what is inside the <BODY> tag.
Using javax.swing.text.html.HTMLEditorKit
In most cases, the HTMLEditorKit is used with a JEditorPane text component but it can be also used directly to extract text from an HTML page. 
import java.io.IOException;
import java.io.FileReader;
import java.io.Reader;
import java.util.List;
import java.util.ArrayList;

import javax.swing.text.html.parser.ParserDelegator;
import javax.swing.text.html.HTMLEditorKit.ParserCallback;
import javax.swing.text.html.HTML.Tag;
import javax.swing.text.MutableAttributeSet;

public class HTMLUtils {
  private HTMLUtils() {}

  public static List<String> extractText(Reader reader) throws IOException {
    final ArrayList<String> list = new ArrayList<String>();

    ParserDelegator parserDelegator = new ParserDelegator();
    ParserCallback parserCallback = new ParserCallback() {
      public void handleText(final char[] data, final int pos) {
        list.add(new String(data));
      }
      public void handleStartTag(Tag tag, MutableAttributeSet attribute, int pos) { }
      public void handleEndTag(Tag t, final int pos) {  }
      public void handleSimpleTag(Tag t, MutableAttributeSet a, final int pos) { }
      public void handleComment(final char[] data, final int pos) { }
      public void handleError(final java.lang.String errMsg, final int pos) { }
    };
    parserDelegator.parse(reader, parserCallback, true);
    return list;
  }

  public final static void main(String[] args) throws Exception{
    FileReader reader = new FileReader("java-new.html");
    List<String> lines = HTMLUtils.extractText(reader);
    for (String line : lines) {
      System.out.println(line);
    }
  }
}
Note that the HTMLEditorKit can be easily confused if the HTML to be parsed is not well-formed.
Using an HTML parser
This is maybe the best solution (if the choosen parser is good !).

There are many parsers available on the net. In this HowTo, I will use the OpenSource package Jsoup.

Jsoup is entirely self contained and has no dependencies which is a good thing. 

import java.io.IOException;
import java.io.FileReader;
import java.io.Reader;
import java.io.BufferedReader;
import org.jsoup.Jsoup;

public class HTMLUtils {
  private HTMLUtils() {}

  public static String extractText(Reader reader) throws IOException {
    StringBuilder sb = new StringBuilder();
    BufferedReader br = new BufferedReader(reader);
    String line;
    while ( (line=br.readLine()) != null) {
      sb.append(line);
    }
    String textOnly = Jsoup.parse(sb.toString()).text();
    return textOnly;
  }

  public final static void main(String[] args) throws Exception{
    FileReader reader = new FileReader
          ("C:/RealHowTo/topics/java-language.html");
    System.out.println(HTMLUtils.extractText(reader));
  }
}
Using Apache Tika

Apache Tika 

import java.io.FileInputStream;
import java.io.InputStream;

import org.apache.tika.metadata.Metadata;
import org.apache.tika.parser.AutoDetectParser;
import org.apache.tika.parser.ParseContext;
import org.apache.tika.parser.Parser;
import org.apache.tika.sax.BodyContentHandler;
import org.xml.sax.ContentHandler;

public class ParseHTMLWithTika {
  public static void main(String args[]) throws Exception {

    InputStream is = null;
    try {

         is = new FileInputStream("C:/Temp/java-x.html");
         ContentHandler contenthandler = new BodyContentHandler();
         Metadata metadata = new Metadata();
         Parser parser = new AutoDetectParser();
         parser.parse(is, contenthandler, metadata, new ParseContext());
         System.out.println(contenthandler.toString());
    }
    catch (Exception e) {
      e.printStackTrace();
    }
    finally {
        if (is != null) is.close();
    }
  }
}
See Extract text from a PDF using Apache Tika, Get Mime Type from a file.

See also Extract links from an HTML page and Remove XML tags from a string to keep only text

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