Develop Reference

Search for a string in html file using Jsoup

Can anyone help me with searching for a particular string in HTML file using Jsoup or any other method. There are inbuilt methods but they help in extracting title or script texts inside a specific tags and not string in general.
In this code I have used one such inbuilt method to extract title from the html page.
But I want to search a string instead.
package dynamic_tester;
import java.io.File;
import java.io.IOException;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
public class tester {
public static void main(String args[])
{
Document htmlFile = null;
{
try {
htmlFile = Jsoup.parse(new File("x.html"), "ISO-8859-1");
}
catch (IOException e)
{
e.printStackTrace();
}
String title = htmlFile.title();
System.out.println("Title = "+title);
}
}
}

Here's a sample. It reads the HTML file as text String and then performs search on that String.
package com.example;
import java.io.FileInputStream;
import java.nio.charset.Charset;
public class SearchTest {
public static void main(String[] args) throws Exception {
StringBuffer htmlStr = getStringFromFile("test.html", "ISO-8859-1");
boolean isPresent = htmlStr.indexOf("hello") != -1;
System.out.println("is Present ? : " + isPresent);
}
private static StringBuffer getStringFromFile(String fileName, String charSetOfFile) {
StringBuffer strBuffer = new StringBuffer();
try(FileInputStream fis = new FileInputStream(fileName)) {
byte[] buffer = new byte[10240]; //10K buffer;
int readLen = -1;
while( (readLen = fis.read(buffer)) != -1) {
strBuffer.append( new String(buffer, 0, readLen, Charset.forName(charSetOfFile)));
}
} catch(Exception ex) {
ex.printStackTrace();
strBuffer = new StringBuffer();
}
return strBuffer;
}
}

I am trying to read the first line in my .txt document in to my program?

I have this written so far, I am just doing a few practice codes from my text book. I cant seem to get this to read the first line in my .txt .
/**
*
*/
import java.util.Scanner; //needed for scanner class
import java.io.*; //needed for File I/O classes
/**
* #author Megan
*
*/
public class Pres {
/**
* #param args
*/
public static void main(String[] args) throws IOException
{
// TODO Auto-generated method stub
Scanner keyboard = new Scanner(System.in);
System.out.print("Enter name of file: C:/User/Frances/Documents/USPres.txt");
String filename = keyboard.nextLine();
File file = new File("C:/User/Frances/Documents/USPres.txt");
Scanner inputFile = new Scanner(file);
String line = inputFile.nextLine();
System.out.println("The first line in the file is: ");
System.out.println(line);
inputFile.close();
}
}
I believe it has to do with this portion of the code:
String line = inputFile.nextLine();
I am not quite sure what to type into the (), if I should type anything at all. I could be wrong. My textbook isn't to clear about the proper format. If you could help, please and thank you. :)

To read txt file do this:
String line = "";
BufferedReader in = null;
try {
in = new BufferedReader(new FileReader(fileName));
while ((line = in.readLine()) != null) {
// do something here
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
It will read all lines in the text but since it's practice go ahead and try to figure out how to read just one line.

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
public class Pres {
public static void main(String[] args) throws FileNotFoundException, IOException {
// BufferedReader is best for read line from file or else
BufferedReader Bfr = new BufferedReader(new FileReader("your_filename_or_path.txt"));
// get first line from file
String firstLinetext = Bfr .readLine();
System.out.println(firstLinetext ); // print first line
}
}

cannot create a txt file

import java.util.Scanner;
import java.io.FileInputStream;
import java.io.PrintWriter;
import java.io.FileOutputStream;
import java.io.FileNotFoundException;
public class Exercise4
{
String name = null;
public String nameInitials(String sentence)
{
PrintWriter outputStream = null;
try
{
outputStream = new PrintWriter(new FileOutputStream("abc.txt."));
outputStream.println(sentence);
}
catch (FileNotFoundException e)
{
System.out.println("File not found.");
System.exit(0);
}
outputStream.close();
Scanner inputStream = null;
try
{
inputStream = new Scanner(new FileInputStream("abc.txt."));
}
catch (FileNotFoundException e)
{
System.out.println("File not found.");
System.exit(0);
}
do
{
String word = inputStream.next();
char initial = word.charAt(0);
name = initial+"."+name;
} while (inputStream.hasNext());
return name;
}
public void main(String[]args)
{
String initials = nameInitials("Bertrand Arthur William Russell");
System.out.println(initials);
}
}
Write a method called nameInitials that takes one String as argument, pertaining to somebody's full name and returns a String of the name's initials. Usage example,
String initials = nameInitials("Bertrand Arthur William Russell");
System.out.println(initials); //should print B.A.W.R.
I try to store the full name to a txt file and read the file. But I don't know why I cannot create the abc.txt file in the folder.

This can fix your error, I tested it
import java.util.Scanner;
import java.io.FileInputStream;
import java.io.PrintWriter;
import java.io.FileOutputStream;
import java.io.FileNotFoundException;
public class Exercise4
{
static String name = null;
public static String nameInitials(String sentence) {
PrintWriter outputStream = null;
try {
outputStream = new PrintWriter(new FileOutputStream("C:\\temp\\abc.txt"));
outputStream.println(sentence);
} catch (FileNotFoundException e) {
System.out.println("File not found.");
System.exit(0);
}
outputStream.close();
Scanner inputStream = null;
try {
inputStream = new Scanner(new FileInputStream("C:\\temp\\abc.txt"));
} catch (FileNotFoundException e) {
System.out.println("File not found.");
System.exit(0);
}
do {
String word = inputStream.next();
char initial = word.charAt(0);
name = initial + "." + name;
} while (inputStream.hasNext());
return name;
}
public static void main(String[] args) {
String initials = nameInitials("Bertrand Arthur William Russell");
System.out.println(initials);
}
}
the path of file not should end of .txt. just .txt

Your code is perfect it is creating the file "abc.txt." at the project level If you want to create a file named abc.txt then you must change;
new FileOutputStream("abc.txt.") to new FileOutputStream("abc.txt")
and
new FileInputStream("abc.txt.") to new FileInputStream("abc.txt")
And if you want to create the file in a particular directory then provide the full path of that directory with the file name you want to create.
for ubuntu system;
new FileOutputStream("/home/java/abc.txt")
&
new FileInputStream("/home/java/abc.txt")
and for windows system;
new FileOutputStream("C:/java/abc.txt")
&
new FileInputStream("C:/java/abc.txt")

FileReader Error when I read a text file

I am trying to store string of array in a text file and read it. But I can't get it working. I am getting NullPointerError.
Exception in thread "main" java.lang.NullPointerException
at java.io.FileInputStream.<init>(Unknown Source)
at java.io.FileReader.<init>(Unknown Source)
at in.isuru.justconverter.FileDbTool.readFile(FileDbTool.java:41)
at in.isuru.justconverter.Test.main(Test.java:10)
Here's two classes.
package in.isuru.justconverter;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.StringTokenizer;
import javax.swing.JOptionPane;
public class FileDbTool {
File dataFile;
ArrayList<String> filePath;
public void checkFile(){
dataFile = new File("db.txt");
if(dataFile.exists()){
readFile();
}else{
try {
dataFile.createNewFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
JOptionPane.showMessageDialog(null, "Coudn't Create New File!");
System.exit(1);
}
}
}
public void readFile(){
int len;
try{
char[] chr = new char[4096];
StringBuffer buffer = new StringBuffer();
FileReader reader = new FileReader(dataFile);
try {
while ((len = reader.read(chr)) > 0) {
buffer.append(chr, 0, len);
}
}finally {
reader.close();
}
System.out.println(buffer.toString());
StringTokenizer st = new StringTokenizer(buffer.toString(), ",");
while (st.hasMoreTokens()) {
String value = st.nextToken();
filePath = null;
filePath = new ArrayList<String>();
filePath.add(value);
}
}catch(IOException e){
JOptionPane.showMessageDialog(null, "Read Error");
}
}
public String[] getFilePathArray(){
readFile();
return filePath.toArray(new String[filePath.size()]);
}
public File[] getFiles(){
String[] paths = getFilePathArray();
ArrayList<File> files = new ArrayList<File>();
for(int i = 0; i < paths.length; i++){
File file = new File(paths[i]);
files.add(file);
}
return files.toArray(new File[files.size()]);
}
public void eraseFile(){
dataFile.delete();
}
public void writeFile(String[] stuff){
try{
BufferedWriter out = new BufferedWriter(new FileWriter(dataFile, true));
out.append(stuff + ",");
}catch(IOException e){
}
}
public void writeToDb(String[] array){
writeFile(array);
}
}
And main class
package in.isuru.justconverter;
public class Test {
/**
* #param args
*/
public static void main(String[] args) {
FileDbTool app = new FileDbTool();
app.checkFile();
}
}
Well this is a portion of a swing program. I am trying to use text file as a small database.

Line 41 is this:
FileReader reader = new FileReader(dataFile);
so I'd wager that dataFile is null here.
However, you do seem to initialize it before calling this method, otherwise the exception would be thrown inside checkFile.
Are you sure you are not calling readFile directly somewhere without calling checkFile first? In any case, this pattern is not a recommended approach, because you are requiring the users of your class to call methods in a specific order.

From the stack trace , it seems like you called readfile() directly from main rather than through checkfile() . So dataFile is null since it is not initialized by checkfile . Also the stack trace and the given code doesn't match . When FileReader constructor is called with null argument , it will throw NullPointerException when it reaches FileInputstream constructor .
Here is the code from jdk source :
public FileInputStream(File file) throws FileNotFoundException {
String name = (file != null ? file.getPath() : null);
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(name);
}
if (name == null) {
throw new NullPointerException();
}
fd = new FileDescriptor();
fd.incrementAndGetUseCount();
open(name);
}

Remove Duplicate Lines from Text using Java

I was wondering if anyone has logic in java that removes duplicate lines while maintaining the lines order.
I would prefer no regex solution.

public class UniqueLineReader extends BufferedReader {
Set<String> lines = new HashSet<String>();
public UniqueLineReader(Reader arg0) {
super(arg0);
}
#Override
public String readLine() throws IOException {
String uniqueLine;
if (lines.add(uniqueLine = super.readLine()))
return uniqueLine;
return "";
}
//for testing..
public static void main(String args[]) {
try {
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream(
"test.txt");
UniqueLineReader br = new UniqueLineReader(new InputStreamReader(fstream));
String strLine;
// Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Print the content on the console
if (strLine != "")
System.out.println(strLine);
}
// Close the input stream
in.close();
} catch (Exception e) {// Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
}
Modified Version:
public class UniqueLineReader extends BufferedReader {
Set<String> lines = new HashSet<String>();
public UniqueLineReader(Reader arg0) {
super(arg0);
}
#Override
public String readLine() throws IOException {
String uniqueLine;
while (lines.add(uniqueLine = super.readLine()) == false); //read until encountering a unique line
return uniqueLine;
}
public static void main(String args[]) {
try {
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream(
"/home/emil/Desktop/ff.txt");
UniqueLineReader br = new UniqueLineReader(new InputStreamReader(fstream));
String strLine;
// Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Print the content on the console
System.out.println(strLine);
}
// Close the input stream
in.close();
} catch (Exception e) {// Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
}

If you feed the lines into a LinkedHashSet, it ignores the repeated ones, since it's a set, but preserves the order, since it's linked. If you just want to know whether you've seena given line before, feed them into a simple Set as you go on, and ignore those which the Set already contains/contained.

It can be easy to remove duplicate line from text or File using new java Stream API. Stream support different aggregate feature like sort,distinct and work with different java's existing data structures and their methods. Following example can use to remove duplicate or sort the content in File using Stream API
package removeword;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.OpenOption;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.Scanner;
import java.util.stream.Stream;
import static java.nio.file.StandardOpenOption.*;
import static java.util.stream.Collectors.joining;
public class Java8UniqueWords {
public static void main(String[] args) throws IOException {
Path sourcePath = Paths.get("C:/Users/source.txt");
Path changedPath = Paths.get("C:/Users/removedDouplicate_file.txt");
try (final Stream<String> lines = Files.lines(sourcePath )
// .map(line -> line.toLowerCase()) /*optional to use existing string methods*/
.distinct()
// .sorted()) /*aggregrate function to sort disctincted line*/
{
final String uniqueWords = lines.collect(joining("\n"));
System.out.println("Final Output:" + uniqueWords);
Files.write(changedPath , uniqueWords.getBytes(),WRITE, TRUNCATE_EXISTING);
}
}
}

Read the text file using a BufferedReader and store it in a LinkedHashSet. Print it back out.
Here's an example:
public class DuplicateRemover {
public String stripDuplicates(String aHunk) {
StringBuilder result = new StringBuilder();
Set<String> uniqueLines = new LinkedHashSet<String>();
String[] chunks = aHunk.split("\n");
uniqueLines.addAll(Arrays.asList(chunks));
for (String chunk : uniqueLines) {
result.append(chunk).append("\n");
}
return result.toString();
}
}
Here's some unit tests to verify ( ignore my evil copy-paste ;) ):
import org.junit.Test;
import static org.junit.Assert.*;
public class DuplicateRemoverTest {
#Test
public void removesDuplicateLines() {
String input = "a\nb\nc\nb\nd\n";
String expected = "a\nb\nc\nd\n";
DuplicateRemover remover = new DuplicateRemover();
String actual = remover.stripDuplicates(input);
assertEquals(expected, actual);
}
#Test
public void removesDuplicateLinesUnalphabetized() {
String input = "z\nb\nc\nb\nz\n";
String expected = "z\nb\nc\n";
DuplicateRemover remover = new DuplicateRemover();
String actual = remover.stripDuplicates(input);
assertEquals(expected, actual);
}
}

Here's another solution. Let's just use UNIX!
cat MyFile.java | uniq > MyFile.java
Edit: Oh wait, I re-read the topic. Is this a legal solution since I managed to be language agnostic?

For better/optimum performance, it's wise to use Java 8's API features viz. Streams & Method references with LinkedHashSet for Collection as below:
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.LinkedHashSet;
import java.util.stream.Collectors;
public class UniqueOperation {
private static PrintWriter pw;
enter code here
public static void main(String[] args) throws IOException {
pw = new PrintWriter("abc.txt");
for(String p : Files.newBufferedReader(Paths.get("C:/Users/as00465129/Desktop/FrontEndUdemyLinks.txt")).
lines().
collect(Collectors.toCollection(LinkedHashSet::new)))
pw.println(p);
pw.flush();
pw.close();
System.out.println("File operation performed successfully");
}

here I'm using a hashset to store seen lines
Scanner scan;//input
Set<String> lines = new HashSet<String>();
StringBuilder strb = new StringBuilder();
while(scan.hasNextLine()){
String line = scan.nextLine();
if(lines.add(line)) strb.append(line);
}