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Asked: 2026-06-02T15:36:28+00:00

I have one java file for web Crowler. That gives me error like multiple

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I have one java file for web Crowler. That gives me error like multiple markers at line and some line number .

I am just learned the pattern and matcher. so i am unable to correct the error.

my code is 

 import java.awt.*;
 import java.awt.event.*;
 import java.io.BufferedReader;
 import java.awt.*;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.net.URL;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;


 class initComponents extends Frame implements ActionListener {

      // TextField addt  ,factorialt,concatt1,concatt2,lengtht,palindromet,comparet1,comparet2,substringt1,substringt2;
    //Button add1,factorial1,concat1,length1,palindrome1,compare1,substring1;
 String s1="";
//String s3="";
//String s4="";
//String s2="";
 Button Search,Clear;
 TextField text1;
 TextArea text2;
Label lab,lab1,lab2;

public initComponents()
{
        MyWindowAdapter1 m=new MyWindowAdapter1(this);
        addWindowListener(m);

        setTitle("Web Crawler");
        setLayout(null);
        setSize(1000,1000);
        setVisible(true);

        setBackground(Color.LIGHT_GRAY);

        lab=new Label("Name: ");
        text1=new TextField(20);
        //text2=new TextArea(80,80);
        text2=new TextArea();

       //lab1=new Label("Count");
       //lab2=new Label(); 

        Search=new Button("Search");
        Clear=new Button("Clear");

        lab.setBounds(50,50,80,20);
        //lab1.setBounds(500,50,80,20);
        //lab2.setBounds(590,50,250,20);

        text1.setBounds(140,50,250,20);
        Search.setBounds(50,100,80,20);
        Clear.setBounds(150,100,80,20); 
        text2.setBounds(50, 200, 700, 500);
        //text2.setBounds(200,100,80,20);

        add(lab);
        add(text1);
        //add(lab1);
        //add(lab2);
        add(Search);
        add(Clear);
        add(text2);


        setVisible(true);
        setSize(800,800);

        Search.addActionListener(this);
        Clear.addActionListener(this);



}


 public void actionPerformed(ActionEvent a) 
  {
// TODO Auto-generated method stub



if(a.getSource().equals(Clear))
{
    text1.setText("");
    text2.setText("");
    //text2.append("");
}

    if(a.getSource().equals(Search))
    {
        s1=text1.getText();

        text2.setText("");
        //text2.append();
        //web_crawler c=new web_crawler();

        //c.crawling(s1);


        try{
             InputStreamReader in = new InputStreamReader(new URL(s1).openStream());
             StringBuilder input = new StringBuilder();

             int ch;

             while ((ch = in.read()) != -1) 
                 input.append((char) ch);

             String patternString = "<a\\s+href\\s*=\\s*(\"[^\"]*\"|[^\\s>])\\s*>";


             String abc=((?<html>(href|src)\s*=\s*")|(?<css>url\())(?<url>.*?)(?(html)"|\));  **// here is error**
             Pattern pattern = Pattern.compile(abc, Pattern.CASE_INSENSITIVE);
             Matcher matcher = pattern.matcher(input);
             int count=0;
             String abc="";

             System.out.println(pattern);
             System.out.println(matcher.toString());

             while (matcher.find()) 
             {

                 int start = matcher.start();
                 int end = matcher.end();
                 String match = input.substring(start, end);

                 //match.matches();
             //jTextArea1.append(match);
             //jTextArea1.append("\n");

                 //String[] tokens=match.split(" ");


                 //System.out.println(tokens[0].toString());



                 text2.append(match);
                 text2.append("\n");
             }




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



    }

}

}

    class MyWindowAdapter1 extends WindowAdapter{
initComponents mf;
public MyWindowAdapter1(initComponents mf){
this.mf=mf;
}

public void windowClosing(WindowEvent we)
  {
      System.exit(0);
 } 
 }

it gives errors like

     Exception in thread "AWT-EventQueue-0" java.lang.Error: Unresolved compilation problems: 
Syntax error on token "?", new expected
Syntax error on token ">", Type expected after this token
Syntax error on token "Invalid Character", invalid AssignmentOperator
Syntax error on token "Invalid Character", delete this token
Syntax error on tokens, Expression expected instead

at initComponents.actionPerformed(initComponents.java:115)
at java.awt.Button.processActionEvent(Unknown Source)
at java.awt.Button.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Please help me. Thanks

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1 Answer

  1. Editorial Team

    You need to add quotation marks around your literal and add the correct escape sequences. Also you declare String abc twice:

    String abc=((?<html>(href|src)\s*=\s*")|(?<css>url\())(?<url>.*?)(?(html)"|\));  **// here is error**
Pattern pattern = Pattern.compile(abc, Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(input);
int count=0;
String abc=""; **redeclaration here**

    change it to:

    String abc="((?<html>(href|src)\\s*=\\s*\")|(?<css>url\\())(?<url>.*?)(?(html)\"|\\))";
Pattern pattern = Pattern.compile(abc, Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(input);
int count=0;
abc="";
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