Develop Reference

How to remove row which contains blank cell from csv file in Java

I'm trying to do data cleaning on dataset. by data cleaning i meant removing the row which containes NaN or duplicates values or empty cell. here is my code
dataset look like this:
Sno Country noofDeaths
1 32432
2 Pakistan NaN
3 USA 3332
3 USA 3332
excel file image:
public class data_reader {
String filePath="src\\abc.csv";
public void readData() {
BufferedReader br = null;
String line = "";
HashSet<String> lines = new HashSet<>();
try {
br = new BufferedReader(new FileReader(filePath));
while ((line = br.readLine()) != null) {
if(!line.contains("NaN") || !line.contains("")) {
if (lines.add(line)) {
System.out.println(line);
}
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
it is working fine for NaN values and duplicates rows but not for empty cell, please help how to do this.
!line.contains("")
this is not working.

Condition !line.contains("") - doesn't make sence because every string contains empty string.
General suggestions:
don't hard code file-path, code must be reusable;
use try with resources;
camel-case names.
public class DataReader {
public static void main(String[] args) {
new DataReader().readData("src\\abc.csv");
}
public void readData(String filePath) {
try(BufferedReader br = new BufferedReader(new FileReader(filePath))) {
HashSet<String> lines = new HashSet<>();
String line = null;
while ((line = br.readLine()) != null) {
if(!line.contains("NaN")) {
for (String cell: line.split(",")) {
if (!cell.isBlank()&&lines.add(cell)) {
System.out.print(cell + " ");
}
}
}
System.out.println();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}

Seems to me this is a pretty easy problem to solve. Given a CSV file with an empty row
foo,bar,baz
1,One,123
,,
2,Two,456
3,Three,789
You can read the lines and define an empty line as one which contains empty strings separated by commas. You could read the contents of the file, store the populated lines into a string buffer, and then save the contents of the buffer once the empty lines are extracted out. The code below accomplishes this:
public static void main(String[] args) throws IOException {
String file ="test.csv";
BufferedReader reader = new BufferedReader(new FileReader(file));
String line = null;
StringBuilder sbuff = new StringBuilder();
while ((line = reader.readLine()) != null) {
String[] tokens = line.split(",");
if (containsText(tokens)) {
sbuff.append(line + "\n");
}
}
reader.close();
System.out.println(sbuff.toString());
// save file here
}
public static boolean containsText(String[] tokens) {
for (String token: tokens) {
if (token.length() > 0)
return true;
}
return false;
}
After running the code, the output is:
foo,bar,baz
1,One,123
2,Two,456
3,Three,789
This same code can be used to determine if a cell is empty with a simple method:
public static boolean isCellEmpty(String[] tokens) {
for (String token: tokens) {
if (token.isBlank())
return true;
}
return false;
}

I want to split textfile into mutilple text files

Hi I have Text file having some tag based data and i want to split into multiple text files.
Main Text files having data like this:
==========110CYL067.txt============
<Entity Text>Cornell<Entity Type>Person
<Entity Text>Donna<Entity Type>Person
<Entity Text>Sherry<Entity Type>Person
<Entity Text>Goodwill<Entity Type>Organization
==========110CYL068.txt============
<Entity Text>Goodwill Industries Foundation<Entity Type>Organization
<Entity Text>Goodwill<Entity Type>Organization
NOTE: Over here 110CYL068.txt and 110CYL067.txt are text files.
I want to split this file into 110CYL068.txt and 110CYL067.txt and so on.
This ============ pattern is fixed.Between ============ FileName ============
file name could be anything.does anyone have any insight.

I don't want to write codes for you, so you can read the file using a BufferedReader or FileReader. You can create and write to a new File using any file writer whenever you see a line starting with ======= or containing .txt.
If you encounter those close the previous file and repeat the process.

Done ppl way to complicatet just did it fast and dirty.
public static List<String> lines = new ArrayList<String>();
public static String pattern = "==========";
public static void main(String[] args) throws IOException {
addLines(importFile());
}
private static List<String> importFile() throws FileNotFoundException, IOException {
BufferedReader br = new BufferedReader(new FileReader("C:\\temp\\test.txt"));
try {
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
lines.add(line.replaceFirst(pattern, ";") + "\n");
line = br.readLine();
}
} finally {
br.close();
}
return lines;
}
private static void addLines(List<String> list) throws IOException {
String FilesString = list.toString();
System.out.println(FilesString);
String[] FilesArray = FilesString.split(";");
for (String string : FilesArray) {
createFile(string);
}
}
private static void createFile(String content) throws IOException {
String[] Lines = content.replaceAll("=", "").split("\n");
File file = new File("C:\\temp\\" + Lines[0]);
file.createNewFile();
FileWriter writer = new FileWriter(file);
Lines[0] = null;
for (String Line : Lines) {
if (Line != null) {
writer.append(Line.replace(",", "")+"\n");
}
}
writer.flush();
writer.close();
}
}

Also quick and dirty, not using regex. I don't really recommend doing it like this because the for loop in main is quite confusing and could break, but it might be beneficial to use this for ideas.
import java.io.*;
import java.util.*;
class splitFiles {
public static void main(String[] args){
try {
List<String> fileRead = readFiles("some.txt");
for(int i=0; i<fileRead.size(); i++){
if(fileRead.get(i).charAt(0) == '='){
PrintWriter writer = new PrintWriter(getFileName(fileRead.get(i)), "UTF-8");
for(int j=i+1; j<fileRead.size(); j++){
if(fileRead.get(j).charAt(0) == '='){
break;
} else {
writer.println(fileRead.get(j));
}
}
writer.close();
}
}
} catch (Exception e){
}
}
public static String getFileName(String fileLine){
String[] split = fileLine.split("=");
for(String e: split){
if(e.isEmpty()){
continue;
} else {
return e;
}
}
return "No file name found";
}
public static ArrayList<String> readFile(String path){
try {
Scanner s = new Scanner(new File(path));
ArrayList<String> list = new ArrayList<String>();
while(s.hasNext()){
list.add(s.next());
}
s.close();
return list;
} catch (FileNotFoundException f){
System.out.println("File not found.");
}
return null;
}
static List<String> readFiles(String fileName) throws IOException {
List<String> words = new ArrayList<String>();
BufferedReader reader = new BufferedReader(new FileReader(fileName));
String line;
while ((line = reader.readLine()) != null) {
words.add(line);
}
reader.close();
return words;
}
}

can't find symbol error, java

I declared a global vector, and I'm trying to access it globally, but it throws an error.
It says cannot find symbol XArray or YArray.
The code I'm using (I've cut some of it out that I thought was not necessary):
public class Main {
public static void main(String[] args) {
String csvFile = "/Users/hherzberg/Desktop/testData.csv";
BufferedReader br = null;
String line = "";
String cvsSplitBy = ",";
ArrayList<Point3D> myPoints = new ArrayList<Point3D>();
ArrayList<Double> XArray = new ArrayList<Double>();
ArrayList<Double> YArray = new ArrayList<Double>();
try {
int xcount=0;
int ycount=0;
double multiplied=0;
br = new BufferedReader(new FileReader(csvFile));
br.readLine();
while ((line = br.readLine()) != null) {
// use comma as separator
String[] number = line.split(cvsSplitBy);
double x = Double.parseDouble(number[0]);
double y = Double.parseDouble(number[1]);
XArray.add(x);
YArray.add(y);
Point3D p = new Point3D(x, y);
myPoints.add(p);
xcount+=1;
ycount+=1;
System.out.println(p);
}
for (int i=0; i<myPoints.size();i++)
{
multiplied+=Double.parseDouble(XArray(i))*Double.parseDouble(YArray(i+1));
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
Some help with this would be greatly appreciated.

Use below import at first line and it should work
import java.io.*;
import java.util.*;

I need to get a file reader to read a text file line by line and format them in Java

I have a text file, formatted as follows:
Han Solo:1000
Harry:100
Ron:10
Yoda:0
I need to make an arrayList of objects which store the player's name (Han Solo) and their score (1000) as attributes. I would like to be able to make this arrayList by reading the file line by line and splitting the string in order to get the desired attributes.
I tried using a Scanner object, but didn't get far. Any help on this would be greatly appreciated, thanks.

You can have a Player class like this:-
class Player { // Class which holds the player data
private String name;
private int score;
public Player(String name, int score) {
this.name = name;
this.score = score;
}
// Getters & Setters
// Overrride toString() - I did this. Its optional though.
}
and you can parse your file which contains the data like this:-
List<Player> players = new ArrayList<Player>();
try {
BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("input.txt"))); // I used BufferedReader instead of a Scanner
String line = null;
while ((line = br.readLine()) != null) {
String[] values = line.split(":"); // Split on ":"
players.add(new Player(values[0], Integer.parseInt(values[1]))); // Create a new Player object with the values extract and add it to the list
}
} catch (IOException ioe) {
// Exception Handling
}
System.out.println(players); // Just printing the list. toString() method of Player class is called.

You can create a Class call player. playerName and score will be the attributes.
public class Player {
private String playerName;
private String score;
// getters and setters
}
Then you can create a List
List<Player> playerList=new ArrayList<>();
Now you can try to do your task.
Additionally, you can read from file and split each line by : and put first part as playerName and second part as score.
List<Player> list=new ArrayList<>();
while (scanner.hasNextLine()){
String line=scanner.nextLine();
Player player=new Player();
player.setPlayerName(line.split(":")[0]);
player.setScore(line.split(":")[1]);
list.add(player);
}

If you have Object:
public class User
{
private String name;
private int score;
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public int getScore()
{
return score;
}
public void setScore(int score)
{
this.score = score;
}
}
Make an Reader class that reads from the file :
public class Reader
{
public static void main(String[] args)
{
List<User> list = new ArrayList<User>();
File file = new File("test.txt");
BufferedReader reader = null;
try
{
reader = new BufferedReader(new FileReader(file));
String line;
while ((line = reader.readLine()) != null)
{
String[] splitedString = line.split(":");
User user = new User();
user.setName(splitedString[0]);
user.setScore(Integer.parseInt(splitedString[1]));
list.add(user);
}
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
if (reader != null)
{
try
{
reader.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
for (User user : list)
{
System.out.println(user.getName()+" "+user.getScore());
}
}
}
The output will be :
Han Solo 1000
Harry 100
Ron 10
Yoda 0

Let's assume you have a class called Player that comprises two data members - name of type String and score of type int.
List<Player> players=new ArrayList<Player>();
BufferedReader br=null;
try{
br=new BufferedReader(new FileReader("filename"));
String record;
String arr[];
while((record=br.readLine())!=null){
arr=record.split(":");
//Player instantiated through two-argument constructor
players.add(new Player(arr[0], Integer.parseInt(arr[1])));
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
finally{
if(br!=null)
try {
br.close();
} catch (IOException e1) {
e1.printStackTrace();
}
}

For small files (less than 8kb), you can use this
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
public class NameScoreReader {
List<Player> readFile(final String fileName) throws IOException
{
final List<Player> retval = new ArrayList<Player>();
final Path path = Paths.get(fileName);
final List<String> source = Files.readAllLines(path, StandardCharsets.UTF_8);
for (final String line : source) {
final String[] array = line.split(":");
if (array.length == 2) {
retval.add(new Player(array[0], Integer.parseInt(array[1])));
} else {
System.out.println("Invalid format: " + array);
}
}
return retval;
}
class Player {
protected Player(final String pName, final int pScore) {
super();
this.name = pName;
this.score = pScore;
}
private String name;
private int score;
public String getName()
{
return this.name;
}
public void setName(final String name)
{
this.name = name;
}
public int getScore()
{
return this.score;
}
public void setScore(final int score)
{
this.score = score;
}
}
}

Read the file and convert it to string and split function you can apply for the result.
public static String getStringFromFile(String fileName) {
BufferedReader reader;
String str = "";
try {
reader = new BufferedReader(new FileReader(fileName));
String line = null;
StringBuilder stringBuilder = new StringBuilder();
while ((line = reader.readLine()) != null) {
stringBuilder.append(line);
stringBuilder.append("\n");
}
str = stringBuilder.toString();
} catch (IOException e) {
e.printStackTrace();
}
return str;
}
public static void main(String[] args) {
String stringFromText = getStringFromFile("C:/DBMT/data.txt");
//Split and other logic goes here
}

Sorting a text file in Java

I have a text file with a list of words which I need to sort in alphabetical order using Java. The words are located on seperate lines.
How would I go about this, Read them into an array list and then sort that??

This is a simple four step process, with three of the four steps addressed by Stackoverflow Questions:
Read each line and turn them into Java String
Store each Java String in a Array (don't think you need a reference for this one.)
Sort your Array
Write out each Java String in your array

Here is an example using Collections sort:
public static void sortFile() throws IOException
{
FileReader fileReader = new FileReader("C:\\words.txt");
BufferedReader bufferedReader = new BufferedReader(fileReader);
List<String> lines = new ArrayList<String>();
String line = null;
while ((line = bufferedReader.readLine()) != null) {
lines.add(line);
}
bufferedReader.close();
Collections.sort(lines, Collator.getInstance());
FileWriter writer = new FileWriter("C:\\wordsnew.txt");
for(String str: lines) {
writer.write(str + "\r\n");
}
writer.close();
}
You can also use your own collation like this:
Locale lithuanian = new Locale("lt_LT");
Collator lithuanianCollator = Collator.getInstance(lithuanian);

import java.io.*;
import java.util.*;
public class example
{
TreeSet<String> tree=new TreeSet<String>();
public static void main(String args[])
{
new example().go();
}
public void go()
{
getlist();
System.out.println(tree);
}
void getlist()
{
try
{
File myfile= new File("C:/Users/Rajat/Desktop/me.txt");
BufferedReader reader=new BufferedReader(new FileReader(myfile));
String line=null;
while((line=reader.readLine())!=null){
addnames(line);
}
reader.close();
}
catch(Exception ex)
{
ex.printStackTrace();
}
}
void addnames(String a)
{
tree.add(a);
for(int i=1;i<=a.length();i++)
{
}
}
}

public List<String> readFile(String filePath) throws FileNotFoundException {
List<String> txtLines = new ArrayList<>();
try {
BufferedReader reader = new BufferedReader(new FileReader(filePath));
String line;
while (!((line = reader.readLine()) == null)) {
txtLines.add(line);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return txtLines.stream().sorted().collect(Collectors.toList());
}