We Keep Coding

Java - splitting files by newline

How can I split file by newline? I've attempted to split by doing line.split("\\r?\\n") - but when I try printing the 0th index I get the entire file content when I was expecting just the first line. but if I try printing the result at index 0 I get the entire file content, when I expected to get just the first line.
FileInputStream file = new FileInputStream("file.rcp");
BufferedReader reader = new BufferedReader(new InputStreamReader(file));
String line = reader.readLine();
while (line != null) {
String [] split = line.split("\\r?\\n");
String name = split[0]; // test to see if name will print the first line only
System.out.println(name);
line = reader.readLine();
}
File format
Food name - gyros
author - some name
Cusine type - greek
Directions - some directions
Ingredients - some ingredients

The documentation, i.e. the javadoc of readline(), says:
Returns a String containing the contents of the line, not including any line-termination characters
Which means that line.split("\\r?\\n") is the same as new String[] { line }, i.e. it's an entirely useless thing to do.
If you want to read the entire file into memory as an array of lines, just call Files.readAllLines():
List<String> linesList = Files.readAllLines(Paths.get("file.rcp"));
String[] linesArray = linesList.toArray(new String[0]);

You do not need to split any string at all. You can simply read a line and add it to a List<String> (or an array if the number of lines is known).
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class Main {
public static void main(String[] args) throws IOException {
FileInputStream file = new FileInputStream("file.rcp");
List<String> list = new ArrayList<>();
try (BufferedReader reader = new BufferedReader(new InputStreamReader(file))) {
String line = reader.readLine();
while (line != null) {
list.add(line);
line = reader.readLine();
}
}
System.out.println(list);
// An array out of the list
String[] arr = list.toArray(new String[0]);
System.out.println(Arrays.toString(arr));
}
}
Output:
[Food name - gyros, author - some name, Cusine type - greek, Directions - some directions, Ingredients - some ingredients]
[Food name - gyros, author - some name, Cusine type - greek, Directions - some directions, Ingredients - some ingredients]
If you have already read the content of your file into some string (e.g. String fileContent as shown below), you can simply split the string on \r?\n which will produce a String[].
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
public class Main {
public static void main(String[] args) throws IOException {
String fileContent = new String(Files.readAllBytes(Paths.get("file.rcp")));
// Java11 onwards
// String fileContent = Files.readString(Path.of("file.rcp"));
String[] arr = fileContent.split("\\r?\\n");
System.out.println(Arrays.toString(arr));
}
}
Output:
[Food name - gyros, author - some name, Cusine type - greek, Directions - some directions, Ingredients - some ingredients]

Reading text files in Java and using data

I am required to evaluate the contents of a .txt file, the file includes 5 numbers, all spaced apart by one (ex: 5555 55 45 47 85) on one line.
The problem isn't reading the file, but actually using each number in the file.
Question: How can I grab the 5 numbers and store each into a unique variable?
Code so far:
import java.io.FileReader;
import java.io.BufferedReader;
public class PassFail {
public static void main(String[] args) {
try{
FileReader file = new FileReader("C:\\new_java\\Final_Project\\src\\student.txt");
BufferedReader reader = new BufferedReader(file);
String line = reader.readLine();
reader.close();
System.out.println(line);
} catch(Exception e) {System.out.println("Error:"+ e);}
}
}

You need to read the file line by line, which you already did. Then you can split the string on space character and iterate over the fields and parse them to Integer
s= reader.readline()
String tokens[]= s.split(" ");
int nums[] = new int[tokens.length];
for(int i=0; i<tokens.lenght; i++) {
nums[i] = Integer.parseInt(tokens[i]);
}
Hope this helps.

How to store text from a certain column in an arraylist?

I would like to store only the first column that is contained in the .txt file.
hello28 23232
hello27 23232
hello25 12321
This is the code I have so far, however at the moment it stores every line in the file; how can I make it so that only the first column is stored (The one which contains the user names of the users)?
public static boolean checkUserExists(String userName){
String line = "";
ArrayList <String> userNames = new ArrayList <String>();
try{
FileReader fr = new FileReader("investments.txt");
BufferedReader br = new BufferedReader(fr);
while((line = br.readLine()) != null) {
userNames.add(line);
}
}
catch(IOException e){
System.out.println("File not found!");
}
if (userNames.contains(userName)){
return false;
}
else{
return true;
}
}

All you need to do is just to split each line using whitespace as a delimiter and keep the first token, and repeat that for every line:
This can be achieved using the following line of code which uses the split function (see more info here http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#split(java.lang.String))
line.split("\\s+");
Then, the zero-th (0) element contains the first column, as you wish to do
There you go a fully working class:
import java.io.IOException;
import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
class white {
public static void main(String[] args) {
String line = "";
String username = "";
ArrayList <String> userNames = new ArrayList <String>();
try{
FileReader fr = new FileReader("investments.txt");
BufferedReader br = new BufferedReader(fr);
while((line = br.readLine()) != null) {
line.split("\\s+");
userNames.add(line.split("\\s+")[0]);
System.out.println(line.split("\\s+")[0]);
}
}
catch(IOException e){
System.out.println("File not found!");
}
}
}
OUTPUT:
hello28
hello27
hello25

You can extract the part of the line preceding the first space:
userNames.add(line.substring(0, line.indexOf(' ') ));

Identifying each word in a file

Importing a large list of words and I need to create code that will recognize each word in the file. I am using a delimiter to recognize the separation from each word but I am receiving a suppressed error stating that the value of linenumber and delimiter are not used. What do I need to do to get the program to read this file and to separate each word within that file?
public class ASCIIPrime {
public final static String LOC = "C:\\english1.txt";
#SuppressWarnings("null")
public static void main(String[] args) throws IOException {
//import list of words
#SuppressWarnings("resource")
BufferedReader File = new BufferedReader(new FileReader(LOC));
//Create a temporary ArrayList to store data
ArrayList<String> temp = new ArrayList<String>();
//Find number of lines in txt file
String line;
while ((line = File.readLine()) != null)
{
temp.add(line);
}
//Identify each word in file
int lineNumber = 0;
lineNumber++;
String delimiter = "\t";
//assess each character in the word to determine the ascii value
int total = 0;
for (int i=0; i < ((String) line).length(); i++)
{
char c = ((String) line).charAt(i);
total += c;
}
System.out.println ("The total value of " + line + " is " + total);
}
}

This smells like homework, but alright.
Importing a large list of words and I need to create code that will recognize each word in the file. What do I need to do to get the program to read this file and to separate each word within that file?
You need to...
Read the file
Separate the words from what you've read in
... I don't know what you want to do with them after that. I'll just dump them into a big list.
The contents of my main method would be...
BufferedReader File = new BufferedReader(new FileReader(LOC));//LOC is defined as class variable
//Create an ArrayList to store the words
List<String> words = new ArrayList<String>();
String line;
String delimiter = "\t";
while ((line = File.readLine()) != null)//read the file
{
String[] wordsInLine = line.split(delimiter);//separate the words
//delimiter could be a regex here, gotta watch out for that
for(int i=0, isize = wordsInLine.length(); i < isize; i++){
words.add(wordsInLine[i]);//put them in a list
}
}

You can use the split method of the String class
String[] split(String regex)
This will return an array of strings that you can handle directly of transform in to any other collection you might need.
I suggest also to remove the suppresswarning unless you are sure what you are doing. In most cases is better to remove the cause of the warning than supress the warning.

I used this great tutorial from thenewboston when I started off reading files: https://www.youtube.com/watch?v=3RNYUKxAgmw
This video seems perfect for you. It covers how to save file words of data. And just add the string data to the ArrayList. Here's what your code should look like:
import java.io.*;
import java.util.*;
public class ReadFile {
static Scanner x;
static ArrayList<String> temp = new ArrayList<String>();
public static void main(String args[]){
openFile();
readFile();
closeFile();
}
public static void openFile(){
try(
x = new Scanner(new File("yourtextfile.txt");
}catch(Exception e){
System.out.println(e);
}
}
public static void readFile(){
while(x.hasNext()){
temp.add(x.next());
}
}
public void closeFile(){
x.close();
}
}
One thing that is nice with using the java util scanner is that is automatically skips the spaces between words making it easy to use and identify words.

Read each line in a text file for strings, doubles, and ints an place them in different arrays

this is my first question here so I hope I'm doing this right. I have a programming project that needs to read each line of a tab delimited text file and extract a string, double values, and int values. I'm trying to place these into separate arrays so that I can use them as parameters. This is what I have so far(aside from my methods):
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.Scanner;
public class LoanDriver {
public static void main(String[] args)
{
String[] stringData = new String[9];
Scanner strings = null;
try
{
FileReader read = new FileReader("amounts.txt");//Read text file.
strings = new Scanner(read);
String skip = strings.nextLine();//Skip the first line by storing it in an uncalled variable
strings.useDelimiter("\t *");//Tab delimited
}
catch (FileNotFoundException error)
{}
while (strings.hasNext())
{
String readLine = strings.next();
stringData = readLine.split("\t");
}
}}
If I try to get the [0] value, it skips all the way to the bottom of the file and returns that value, so it works to some extent, but not from the top like it should. Also, I can't incorporate arrays into it because I always get an error that String[] and String is a type mismatch.

Instead of using delimiter, try reading the file line by line using Scanner.nextLine and split each new line you read using String.split ("\t" as argument).
try {
FileReader read = new FileReader("amounts.txt");//Read text file.
strings = new Scanner(read);
String skip = strings.nextLine();//Skip the first line by storing it in an uncalled variable
}
catch (FileNotFoundException error) { }
String line;
while ((line = strings.nextLine()) != null) {
String[] parts = line.split("\t");
//...
}

You are getting the last value in the file when you grab stringData[0] because you overwrite stringData each time you go through the while loop. So the last value is the only one present in the array at the end. Try this instead:
List<String> values = new ArrayList<String>();
while (strings.hasNext()) {
values.add(strings.next());
}
stringData = values.toArray(new String[values.size()]);