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How To Read A Specific Part Of A Line In A Text File In Java?

I have a text file in which I have written some information line by line like this:
name|Number|amount|PIN
How can I read back data In a way that (for example) I will be able to use just the "name" part in a method?
The sample code is shown in the image below.

in the beginning declare a List to collect the accounts:
import java.util.ArrayList;
...
public Account[] inReader() { //BTW: why do you pass an Account[] here?
ArrayList accountList = new ArrayList();
...
}
replace the for(String records : dataRecords) {...} with
String name = dataRecords[0];
String cardNumber = dataRecords[1];
int pin = Integer.parseInt(dataRecords[2]); //to convert the String back to int
double balance = Double.parseDouble(dataRecords[3]);
Account account = new Account(name, cardNumber, pin, balance);
accountList.add(account);
because you already proceed record by record (while ((line = br.readLine())!=null) {...})
in the end return accountList.toArray(new Account[0]);

You can read the text line by line and then use the "|" delimiter to separate the columns.
try (Stream<String> stream = Files.lines(Paths.get(fileName))) {
stream.forEach(System.out::println);
}

You could read the file line-by-line and split on the delimiter '|'.
The following example assumes the filepath is in args[0] and would read then output the name component of the input:
public static void main(String[] args) {
File file = new File(args[0]);
BufferedReader br = new BufferedReader(new FileReader(file));
while(String line = br.readLine()) != null) {
String[] details = line.split("|");
System.out.println(details[0]);
}
}

As mentioned in the comment above, you can simply split the line on your delimiter, |, and go from there.
Something like:
public class Account {
// ...
public static Account parseLine(String line) {
String[] split = line.split("|");
return new Account(split[0], split[1], split[2], split[3]);
}
}
should work fine (assuming you have a constructor which takes the four things you're putting in). If your Account class has more information than this, you can create an AccountView or similarly named class which does only contain the details you have available here. With this, just iterate line by line, parse your lines to one of these Objects, and use it's properties (including the already available getters) when calling other methods which need name, etc.

First, you need to read the whole content of the file or line by line.
Then, for each line you need to create a function to split the line text by a configurable delimiter. This function can receive the column number and it should return the needed value. For example: extractData(line, 0) should return 'name', extractData(line, 2) should return 'amount' etc.
Also, you need some validation: what if there are only 3 columns and you expect 4? You can throw and exception or you can return null/empty.

There are many possible ways to do it. One of them is to make an object that will hold the data. Example since you know that your data will always have name, number, amount and pin then you can make a class like this:
public class MyData {
private String name;
private String number;
private double amount;
private String pin;
// Add getters and setters below
}
Then while reading the text file you can make a list of MyData and add each data. You can do it like this:
try {
BufferedReader reader = new BufferedReader(new FileReader("path\file.txt"));
String line = reader.readLine();
ArrayList<MyData> myDataList = new ArrayList<MyData>();
while (line != null) {
String[] dataParts = line.split("|"); // since your delimiter is "|"
MyData myData = new MyData();
myData.setName(dataParts[0]);
myData.setNumber(dataParts[1]);
myData.setAmount(Double.parseDouble(dataParts[2]));
myData.setPin(dataParts[3]);
myDataList.add(myData);
// read next line
line = reader.readLine();
} catch (IOException e) {
e.printStackTrace();
}
Then you can use the data like this:
myDataList.get(0).getName(); // if you want to get the name of line 1
myDataList.get(1).getPin(); // if you want to get the pin of line 2

You can convert the file into a csv file and use a library specific for reading csv files, e.g. OpenCSV. This will give you more flexibility in handling the data in the file.

Java how to read a line from a text file that has multiple strings and double values?

I want to create a program that reads from a text file with three different parts and then outputs the name. E.g. text file:
vanilla 12 24
chocolate 23 20
chocolate chip 12 12
However, there is a bit of an issue on the third line, as there is a space. So far, my code works for the first two lines, but then throws a InputMismatchException on the third one. How do I make it so it reads both words from one line and then outputs it? My relevant code:
while (in.hasNext())
{
iceCreamFlavor = in.next();
iceCreamRadius = in.nextDouble();
iceCreamHeight = in.nextDouble();
out.println("Ice Cream: " + iceCreamFlavor);
}

In your input file, the separator between fields is composed of multiples spaces, no ?
if yes, you could simply use split method of String object.
You read a line.
You split it to obtain a String array.
String[] splitString = myString.split(" ");
Ther first element «0» is the String, the two others can be parsed as double
This could looks like :
try (BufferedReader br = new BufferedReader(new FileReader("path/to/the/file.txt"))) {
String line;
while ((line = br.readLine()) != null) {
String[] lineSplitted = line.split(" ");
String label = lineSplitted[0];
double d1 = Double.parseDouble(lineSplitted[1]);
double d2 = Double.parseDouble(lineSplitted[2]);
}
} catch (IOException e) {
e.printStackTrace();
}

You can use scanner.useDelimiter to change the delimiter or use a regular expression to parse the line.
//sets delimiter to 2 or more consecutive spaces
Scanner s = new Scanner(input).useDelimiter("(\\s){2-}");
Check the Scanner Javadoc for examples:

How to output an string of ArrayList into a new file?

Hi guys I have this sample text file in which the names of the peopel are stuck together without any spacing in between them. Is it possible for me to put this into a bufferedreader and create a ArrayList to store the values in a string and then to separate the strings by name.
Text file details:
charles_luiharry_pinkertonarlene_purcellwayne_casanova
My code:
try {
BufferedReader in = new BufferedReader(new FileReader(filename));
String str;
List<String> list = new ArrayList<String>();
while ((str = in.readLine()) != null) {
list.add(str);
}
String[] stringArr = list.toArray(new String[0]);
FileWriter writer = new FileWriter("new_users.txt");
for (String ss : list) {
writer.write(ss);
}
writer.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
Expected output :
charles_lui
harry_pinkerton
arlene_purcell
wayne_casanova
Real output:
A duplicate of the sample file.

Just add a line separator to your writer:
writer.write(ss);
writer.write(System.lineSeparator());
If problems with your os, use System.getProperty( "line.separator" )

BufferedReader.readLine() reads and returns a line from the input which ends with \n or \r\n. It cannot detect the boundaries between the names in your input file. Better prepare the input that the names are on different lines.

It's difficult for a human to successfully separate the last-name with first-name of the next name, how can you expect a computer to do so?
Proposed solution -
Modify the sample file and add a separator(say ';') between two names.
Make a lengthy string by concatenating all the lines in the file. When concatenating remove '\n' or '\r\n' from the end of lines. (Optional - Use a StringBuffer for performance).
Split that string into an 'array of valid names'.
This can be done by calling the split(';') method on the lengthy string, with the separator as the argument.
Then, print from the array.

How do I add lines (read from a .txt) separated by AN ENTER KEY (in .txt) into separate elements of string arrayList?

I'm reading .txt file into my program and am adding lines of the .txt into a String arrayList. How do I add lines DELINEATED BY AN ENTER KEY (in .txt) into separate elements of the arrayList? Right now if I had the following written in text:
this is a test
test
test test
It would output:
this is a testtesttest test
What I want it to do is read things on a per line basis, and put it into different elements of the stringArrayList. So I want "this is a test" to be an element, and "test", and then finally "test test".
My code is really ugly, but right now all I want to do is get it to work for my purpose. My first purpose is getting to read a .txt by line. My second purpose is going to be parsing an element for a particular substring (a URL), connecting that URL to the internet, and then comparing a part of that page source of the webpage (parsing for a particular keyword) to the line ABOVE the substring I desire. But that's a question for another time :^)
import java.io.*;
import java.util.*;
public class Test {
public static void main(String [] args) {
// The name of the file to open.
String fileName = "test.txt";
List<String> listA = new ArrayList<String>();
// This will reference one line at a time
String line = null;
try {
// FileReader reads text files in the default encoding.
FileReader fileReader = new FileReader(fileName);
// Always wrap FileReader in BufferedReader.
BufferedReader bufferedReader = new BufferedReader(fileReader);
while((line = bufferedReader.readLine()) != null) {
System.out.println(line);
listA.add(line);
//*** THIS IS WHERE THE MAGIC HAPPENS ***\\ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
}
// Always close files.
bufferedReader.close();
}
catch(FileNotFoundException ex) {
System.out.println(
"Unable to open da file ofheee hah. '" +
fileName + "'");
}
catch(IOException ex) {
System.out.println(
"Error reading file '"
+ fileName + "'");
// Or we could just do this:
// ex.printStackTrace();
}
System.out.println();
System.out.println("array FOr loop thingy incoming:");
System.out.println();
for (int i = 0; i < listA.size(); i++) {
System.out.print((listA.get(i)).toString());
}
}
}

You just have to use println instead of print:
System.out.println((listA.get(i)).toString());
Alternatively, you can add the line break character \n

Your code seems to be working so far. If you just want to see what elements are in listA, just print it out:
System.out.println(listA);
Output:
[this is a test, , test, , test test, ]
Note that the extra lines in your input file are also being stored in listA. I'm not sure if that's the behavior you want.

Read one line of a csv file in Java

I have a csv file that currently has 20 lines of data.
The data contains employee info and is in the following format:
first name, last name, Employee ID
So one line would like this: Emma, Nolan, 2
I know how to write to the file in java and have all 20 lines print to the console, but what I'm not sure how to do is how to get Java to print one specific line to the console.
I also want to take the last employee id number in the last entry and have java add 1 to it one I add new employees. I thinking this needs to be done with a counter just not sure how.

You can do something like this:
BufferedReader reader = new BufferedReader(new FileReader(<<your file>>));
List<String> lines = new ArrayList<>();
String line = null;
while ((line = reader.readLine()) != null) {
lines.add(line);
}
System.out.println(lines.get(0));
With BufferedReader you are able to read lines directly. This example reads the file line by line and stores the lines in an array list. You can access the lines after that by using lines.get(lineNumber).

You can read text from a file one line at a time and then do whatever you want to with that line, print it, compare it, etc...
// Construct a BufferedReader object from the input file
BufferedReader r = new BufferedReader(new FileReader("employeeData.txt"));
int i = 1;
try {
// "Prime" the while loop
String line = r.readLine();
while (line != null) {
// Print a single line of input file to console
System.out.print("Line "+i+": "+line);
// Prepare for next loop iteration
line = r.readLine();
i++;
}
} finally {
// Free up file descriptor resources
r.close();
}
// Remember the next available employee number in a one-up scheme
int nextEmployeeId = i;

BufferedReader reader =new BufferedReader(new FileReader("yourfile.csv"));
String line = "";
while((line=reader.readLine())!=null){
String [] employee =line.trim().split(",");
// if you want to check either it contains some name
//index 0 is first name, index 1 is last name, index 2 is ID
}

Alternatively, If you want more control over read CSV files then u can think about CsvBeanReader that will give you more access over files contents..

Here is an algorithm which I use for reading csv files. The most effective way is to read all the data in the csv file into a 2D array first. It just makes it a lot more flexible to manipulate the data.
That way you can specify which line of the file to print to the console by specifying it in the index of the array and using a for. I.e: System.out.println(employee_Data[1][y]); for record 1. y is the index variable for fields. You would need to use a For Loop of course, to print every element for each line.
By the way, if you want to use the employee data in a larger program, in which it may for example store the data in a database or write to another file, I'd recommend encapsulating this entire code block into a function named Read_CSV_File(), which will return a 2D String array.
My Code
// The return type of this function is a String.
// The CSVFile_path can be for example "employeeData.csv".
public static String[][] Read_CSV_File(String CSVFile_path){
String employee_Data[][];
int x;
int y;
int noofFields;
try{
String line;
BufferedReader in = new BufferedReader(new FileReader(CSVFile_path));
// reading files in specified directory
// This assigns the data to the 2D array
// The program keeps looping through until the line read in by the console contains no data in it i.e. the end of the file.
while ( (( line = in.readLine()) != null ){
String[] current_Record = line.split(",");
if(x == 0) {
// Counts the number of fields in the csv file.
noofFields = current_Record.length();
}
for (String str : values) {
employee_Data[x][y] = str;
System.out.print(", "+employee_Data[x][y]);
// The field index variable, y is incremented in every loop.
y = y + 1;
}
// The record index variable, x is incremented in every loop.
x = x + 1;
}
// This frees up the BufferedReader file descriptor resources
in.close();
/* If an error occurs, it is caught by the catch statement and an error message
* is generated and displayed to the user.
*/
}catch( IOException ioException ) {
System.out.println("Exception: "+ioException);
}
// This prints to console the specific line of your choice
System.out.println(("Employee 1:);
for(y = 0; y < noofFields ; y++){
// Prints out all fields of record 1
System.out.print(employee_Data[1][y]+", ");
}
return employee_Data;
}

For reading large file,
log.debug("****************Start Reading CSV File*******");
copyFile(inputCSVFile);
StringBuilder stringBuilder = new StringBuilder();
String line= "";
BufferedReader brOldFile = null;
try {
String inputfile = inputCSVFile;
log.info("inputfile:" + inputfile);
brOldFile = new BufferedReader(new FileReader(inputfile));
while ((line = brOldFile.readLine()) != null) {
//line = replaceSpecialChar(line);
/*do your stuff here*/
stringBuilder.append(line);
stringBuilder.append("\n");
}
log.debug("****************End reading CSV File**************");
} catch (Exception e) {
log.error(" exception in readStaffInfoCSVFile ", e);
}finally {
if(null != brOldFile) {
try {
brOldFile.close();
} catch (IOException e) {
}
}
}
return stringBuilder.toString();