Question

How do you read a text file into java?

Answer 1

http://www.homeandlearn.co.uk/java/read_a_textfile_in_java.html

Answer 2

```
public void readFile(String path) {
File file = new File(path);
if(!file.exists()) {
print("Your file at path \'" + path + "\' does not appear to be a valid file.");
}
else {
Scanner in = new Scanner(file);
while(in.hasNext()) {
print(in.nextLine());
}
in.close();
}
}
```

Answer 3

```
public void print(String str) {
System.out.println(str);
}
```

Answer 4

Good classes for outputting to a .txt file: PrintWriter class, and if you want to append information, the FileWriter class. Reading in is handled by the Scanner class, and the Scanner class is also useful for reading in keyboard input.

Also, I forgot to put it in the code, but it needs to be in a try/catch block for IOExceptions.

Answer 5

but how is that linking to the text file it should be getting the info from?

Answer 6

I'm not sure I understand the question. you have to supply the path to the file you want to read. Here look at the example woodrow posted above here, his function gets `path` to the file you want to read

Answer 7

ok so if I were to call it in the main method, how would I do that?

is this right?
```
public static void main(String [] args) {
readFile(FileName);
}

Answer 8

Sorry, back. Ye, just put a string for the file path instead of `FileName`.
Remember that `\` is used for for escaping characters in a string, so you to take that into consideration and instead of `C:\test` do `C:\\test` for example

Answer 9

its giving an error

Answer 10

post your full code

Answer 11

@Javk

Answer 12

sorry :\

```

import java.io.*;
import java.util.*;
import java.util.Scanner;

public class Dictionary {

public static void readFile(String path) throws Exception {
File file = new File(path);
if(!file.exists()) {
print("Your file at path \'" + path + "\' does not appear to be a valid file.");
}
else {
Scanner in = new Scanner(file);
while(in.hasNext()) {
print(in.nextLine());
}
in.close();
}
}


public static void print(String str) {
System.out.println(str);
}

public static void main(String[] args) {
readFile("C:\Users\Javeria\Desktop");
}

}

Answer 13

Your path is off- if you have a file called "mytextfile.txt" on your desktop, the correct path would be
```
C:\Users\Javeria\Desktop\mytextfile.txt
```
however, that will probably cause an error, because back slashes in a String represent an 'escape sequence', like doing \t will make a tab, \n will make a newline \" will be a quote, \' will be a single quote, and a \\ will be a single backslash. In Strings, you can use \\ or a single forward slash / to specify a path.

Answer 14

I already tried that
```
public static void main(String[] args) {
readFile("C:\\Users\Javeria\Desktop\user.txt");
}
```
but that was giving an error too: Invalid escape sequence (valid ones are \b \t \n \f \r \" \' \\ )

Answer 15

um, your file path contains single backslashes?

Answer 16

("C:\\Users\\Javeria\\Desktop\\user.txt");

Answer 17

yeah that gave this : Unhandled exception type Exception

Answer 18

try throws IOException

Answer 19

If that doesn't work upload your full code again

Answer 20

Hi pitamar

Answer 21

that didn't work but just throws exception worked

though this time it says:

Error: Main method not found in class Dictionary, please define the main method as:
public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application

```

import java.io.*;
import java.util.*;

public class Dictionary {

public static void readFile(String path) throws Exception {
File file = new File(path);
if(!file.exists()) {
print("Your file at path \'" + path + "\' does not appear to be a valid file.");
}
else {
Scanner in = new Scanner(file);
while(in.hasNext()) {
print(in.nextLine());
}
in.close();
}
}


public static void print(String str) {
System.out.println(str);
}

public static void main(String[] args) throws Exception{
readFile("C:\\Users\\Javeria\\Desktop\\user.txt");
}

}

Answer 22

Hi woodrow lol =)
Let me try and execute this. I'm using linux so the path will be a little different, but still

Answer 23

I may as well try too..

Answer 24

I don't reckon the throws Exception is needed in the main method.. I think.

Answer 25

Looking at the error it seems it doesn't like the `throws exception` for main

Answer 26

funny, program compiled & ran for me.

Answer 27

can you send exactly what you have, beginning to end?

Answer 28

```
import java.io.*;
import java.util.*;

public class Dictionary {

public static void readFile(String path) throws Exception {
File file = new File(path);
if(!file.exists()) {
print("Your file at path \'" + path + "\' does not appear to be a valid file.");
}
else {
Scanner in = new Scanner(file);
while(in.hasNext()) {
print(in.nextLine());
}
in.close();
}
}


public static void print(String str) {
System.out.println(str);
}

public static void main(String[] args) throws Exception{
readFile("C:\\Users\\alex\\Desktop\\mountain.txt");
}

}
```

Answer 29

Idk if you know, but make sure the java file is saved as the class name ```Dictionary.java```

Answer 30

works for me too

Answer 31

make sure your file isn't actually "users.txt.txt".. and also see if a HelloWorld program compiles.. could be a jdk thing.

Answer 32

umm..before i get into that, i just noticed, there is one slightly odd thing

Answer 33

notice the weird red exclamation mark?

Answer 34

You should make Dictionary.java it's own project.. remember, a program can only have one main method.

Answer 35

ooooohhh weeeelll...that wasn't embarrassing at all

Answer 36

now that we are totally over my embarrassment, can ask something that will make you want to wring my neck?

Can I read text file straight into a vector?

Answer 37

xD no worries, everyone learns this stuff at some point. Seems like you're going in the deep end pretty quick- I like it :). Define 'vector'? You can read it in as an int, yes.

Answer 38

hey, hey only I get to diss myself :p @pitamar

ok well...I have a text file which has a list of items in it. These need to go into a vector. Each item is on a separate line by it'self.

The contents of the file are as below:
```
class
instance
object
Pizza
shazam
Pasta
implements
abstract
```
well as you can see they are pretty abstract.

I had been working on this all morning and then accidently permanently deleted it though I just remembered that I had a backup. So this is what I have:
```
import java.io.*;
import java.util.*;
import java.util.Scanner;

public class Dictionary{

public static Vector <String []> fileToVector(String s) throws Exception {
Vector v = new Vector();
FileReader fr = new FileReader("C:\\Users\\Javeria\\Desktop\\user.txt");
Scanner inone = new Scanner(fr);
while (inone.hasNextLine()) v.addElement(inone.nextLine());
return v;
}


public static void main(String [] args) throws Exception{
Vector <String []> w = fileToVector(args[0]);
for (int i = 0; i < w.size(); i++) System.out.println(w.elementAt(i));
}

}
```
it's something I got out of the book

Answer 39

If you do read it in as an int, always put
```
in.next();
```
after each time you read something that isn't in.nextLine();

Answer 40

@Javk Lol sorry I didn't mean it in a bad way
Just saying that it's normal to make mistakes and you shouldn't feel bad about it =)

Answer 41

I mean in.nextLine() after in.nextInt() and before another in.nextLine();
http://stackoverflow.com/questions/13102045/skipping-nextline-after-use-nextint

Answer 42

I'm pretty sure you can only read in Strings and data types - but don't hold me too it, check the javadocs on it. I don't know the Vector class, but there's most likely some way to transform the String into usable data for the Vector.

Answer 43

Ok, so what's wrong with that code? it should add all the lines to the vector, isn't it what you want?

Answer 44

don't wotrry @pitamar

okay so i'll look at this in the morning, thankyoooooo

Answer 45

So, I did a bit of tweaking and now the .dict file is being read into the vector:
```
import java.io.*;
import java.util.*;
import java.util.Scanner;

public class Dictionary{

static Vector v = new Vector();

public static void readFile(String path) throws Exception {
FileReader file = new FileReader(path);
Scanner in = new Scanner(file);
while(in.hasNext()) {
v.addElement(in.nextLine());
}
}

public static void main(String [] args) throws Exception{
readFile("C:\\Users\\Javeria\\Desktop\\user.dict");
System.out.println(v);
}

}

Answer 46

Nice.. so- it works? :D also - when you put an object in System.out.println(); if the object has a toString() method, it will automatically be called. A handy function.

Answer 47

That it seems your making use of :).