I had a lecture today on inputting and outputting but it didn't really seem to explain where the text file is etc..
here is my code:
package inputoutput;
import java.util.*;
import java.io.*;
public class input {
public static void main(String[] args) throws FileNotFoundException {
String name;
int lineCount = 0;
File input = new File("lab1task3.txt");
Scanner in = new Scanner(input);
while(in.hasNextLine()){
lineCount++;
}
System.out.println(lineCount);
}
}
I get a file not found exception but the text file is in the same folder as the program?
Please first read up on the difference between relative and absolute paths. An absolute path is:
C:\Users\Ceri\workspace1\inputoutput\src\inputoutput\lab1task3.txt
A relative path would be just "lab1task3.txt", which is what is given. That means that lab1task3.txt can be found relative to the working directory (e.g if the working directory was "C:\Users\Ceri\workspace1\inputoutput\src\inputoutput\" then it would find it).
However, you could also use an absolute path, but remember that doing so means that it will only work if a file is in the same place on the machine running it. E.g, if you submit with "C:\Users\Ceri\workspace1\inputoutput\src\inputoutput\" in your code then it will only work if someone else has that same file and location on their computer. Please note that if this is an assignment, the module convenor/marker probably does not have afolder called C:\Users\Ceri.... If you submit your work using a relative path, anyone using your code just needs to make sure the file is relatively in the same place (e.g in the same folder).
If this doesn't matter, you need to escape the back slash characters with another back slash in the path. This should work:
package inputoutput;
import java.util.*;
import java.io.*;
public class input {
public static void main(String[] args) throws FileNotFoundException {
String name;
int lineCount = 0;
File input = new File("C:\\Users\\Ceri\\workspace1\\inputoutput\\src\\inputoutput\\lab1task3.txt");
Scanner in = new Scanner(input);
while(in.hasNextLine()){
lineCount++;
}
System.out.println(lineCount);
}
}
I notice you are using eclipse. Your "working directory" is your workspace. Therefore you want to move your file to:
C:\Users\Ceri\workspace1\inputoutput\lab1task3.txt
This should work for you using a "relative" path which you had in your opening post.
You're confusing class file location and the "user's working directory", the latter being what Java uses to determine the root of the file path (unless absolute paths are needed), and you can find its location easily via:
System.out.println(System.getProperty("user.dir"));
I advise you to forgo use of files altogether when all you need to do is read in data, and instead get the text file as a program resource:
// where you swap the name of your class for MyClass
InputStream fileResource = MyClass.class.getResourceAsStream("myFile.txt");
Scanner scanner = new Scanner(inputStream);
Note that if you must use a File, then find out what the user's working directory is, as shown above, and then tailor your file path so that it is relative to this working directory.
Try:
File file = new File("src/inputoutput/lab1task3.txt");
My guess is that your current working directory is not the same place as the project location. If your working directory were, the file would definitely be found if it does indeed have that name.
To workaround this issue you can always be using a InputStream instead, like so:
InputStream inputStream = new InputStream("lab1task3.txt");
Scanner scanner = new Scanner(inputStream);
If you want to see your current working directory you can use something like this:
public class JavaApplication1 {
public static void main(String[] args) {
System.out.println("Working Directory = " +
System.getProperty("user.dir"));
}
}
Related
I am trying to read from a text file. I have the file created, it only needs to have one record, but it could have more. I keep getting errors. I am a Geography student, not an IT guy, I am hoping to figure out the next step once I get this. Here is my example, that doesn't work:
import java.io.*;
import java.util.*;
import java.lang.*;
public class Driver
{
public static void main(String[] args) throws IOException
{
File data;
String fileName = null; // User input file name
Scanner input;
input = new Scanner(System.in);
System.out.println("Enter file name (ie: text.txt): ");
data = new File(input.next());
Scanner read;
read = new Scanner(data);
fileName = read.nextLine();
System.out.println(fileName);
}
}
I believe an error that you are having is not referencing the correct place when trying to access the file. If you just type in example.txt, the java compiler has no idea where to find this file.
Try this:
Right click under the package
Create new folder, and call it 'texts'
Open file explorer
Paste all your .txt files into this new folder 'texts'
Replace fileName = read.nextLine(); with fileName = "texts/" + read.nextLine();
After this you should be good to go!
You have two options.
Put text.txt file in same folder where your class files are.
Get full path of the file from user like C:\text.txt.
It'll run.
First question here on StackOverflow, so apologies if this is bad. But I got a student job programming for civil engineers. My first assignment is to use JFileChooser to allow the user to specify a desired file, and then the full path of this file will be written to a txt file. I want it to automatically write to the file that this program using JFileChooser resides in. I am very confused on how to do this and haven't been able to find anything helpful on that.
My code:
public class FilePathFinder {
JFileChooser fileChooser;
String path;
public static void main(String[] args) throws IOException{
String path = null; //String that will be outputted to
//creates file chooser and its properties
JFileChooser file_chooser = new JFileChooser();
file_chooser.setCurrentDirectory(new java.io.File("user.home"));
file_chooser.setDialogTitle("Create File Path");
file_chooser.setApproveButtonText("Create Path");
file_chooser.setFileSelectionMode(JFileChooser.FILES_AND_DIRECTORIES);
file_chooser.setAcceptAllFileFilterUsed(false);
if (file_chooser.showOpenDialog(null)==JFileChooser.APPROVE_OPTION){
path=(file_chooser.getSelectedFile().getAbsolutePath());
}
//Writes path name to file
String user_home_folder = System.getProperty("user.home");
System.out.println(user_home_folder);
File path_file = new File(user_home_folder, path);
BufferedWriter path_writer = new BufferedWriter(new FileWriter(path_file));
if(!path_file.exists()){
path_writer.write(path);
}
}
}
So what is the problem you are actually having?
A comment:
file_chooser.setCurrentDirectory(new java.io.File("user.home"));
This won't set the current directory to be the users home directory. But to a directory (if it exists) named "user.home" in the current directory. What you probably wanted to do is:
file_chooser.setCurrentDirectory(new java.io.File(System.getProperty("user.home")));
Update By reading your comment on this answer:
You already have an absolute path in your variable path. But using the constructor new File(user_home_folder, path) your prefixing it with the location of the user's home directory. This results in a path like that has for example the drive letter twice in it. Remove the first parameter of this constructor.
i can seem to understand why my code isn't compiling. Everytime I run it, I get a FILENOTFOUNDException. Any help would be much appreciated. :D
public static void main(String args[]) throws IOException
{
Scanner diskScanner =
new Scanner(new File("EmployeeInfo.txt"));
for(int empNum = 1; empNum<=3; empNum++)
{
payOneEmployee(diskScanner);
}
}
static void payOneEmployee(Scanner aScanner)
{
Employee anEmployee = new Employee();
anEmployee.setName(aScanner.nextLine());
anEmployee.setJobTitle(aScanner.nextLine());
anEmployee.cutCheck(aScanner.nextDouble());
aScanner.nextLine();
}
Basically the exception message means the filename you specified is not an existing file in executions directory.
EDIT[copied from my comment]
That file should be located where compilation is done, if you are using eclipse or intellij it should be at your projects root directory.
+ Because you are passing in a relative path and not an absolute one to the file, java is recognizing it as a relative to execution directory which is located where followin code points to.
To check what is that desired input files directory simply use
getAbsolutePath() on that file.
For instance:
File input = new File("EmployeeInfo.txt");
System.out.println("Move .txt to dir:" + input.getAbsolutePath());
Scanner diskScanner = new Scanner(input);
Then move the source .txt file to that location
I'm very new at coding java and I'm having a lot of difficulty.
I'm suppose to write a program using bufferedreader that reads from a file, that I have already created named "scores.txt".
So I have a method named processFile that is suppose to set up the BufferedReader and loop through the file, reading each score. Then, I need to convert the score to an integer, add them up, and display the calculated mean.
I have no idea how to add them up and calculate the mean, but I'm currently working on reading from the file.
It keeps saying that it can't fine the file, but I know for sure that I have a file in my documents named "scores.txt".
This is what I have so far...it's pretty bad. I'm just not so good at this :( Maybe there's is a different problem?
public static void main(String[] args) throws IOException,
FileNotFoundException {
String file = "scores.txt";
processFile("scores.txt");
//calls method processFile
}
public static void processFile (String file)
throws IOException, FileNotFoundException{
String line;
//lines is declared as a string
BufferedReader inputReader =
new BufferedReader (new InputStreamReader
(new FileInputStream(file)));
while (( line = inputReader.readLine()) != null){
System.out.println(line);
}
inputReader.close();
}
There are two main options available
Use absolute path to file (begins from drive letter in Windows or
slash in *.nix). It is very convenient for "just for test" tasks.
Sample
Windows - D:/someFolder/scores.txt,
*.nix - /someFolder/scores.txt
Put file to project root directory, in such case it will be visible
to class loader.
Place the scores.txt in the root of your project folder, or put the full path to the file in String file.
The program won't know to check your My Documents folder for scores.txt
If you are using IntelliJ, create an input.txt file in your package and right click the input.txt file and click copy path. You can now use that path as an input parameter.
Example:
in = new FileInputStream("C:\\Users\\mda21185\\IdeaProjects\\TutorialsPointJava\\src\\com\\tutorialspoint\\java\\input.txt");
Take the absolute path from the local system if you'r in eclipse then right-click on the file and click on properties you will get the path copy it and put as below this worked for me In maven project keep the properties file in src/main/resources `
private static Properties properties = new Properties();
public Properties simpleload() {
String filepath="C:/Users/shashi_kailash/OneDrive/L3/JAVA/TZA/NewAccount/AccountConnector/AccountConnector-DEfgvf/src/main/resources/sample.properties";
try(FileInputStream fis = new FileInputStream(filepath);) {
//lastModi = propFl.lastModified();
properties.load(fis);
} catch (Exception e) {
System.out.println("Error loading the properties file : sample.properties");
e.printStackTrace();
}
return properties;
}`
So here is my program, which works ok:
import java.io.FileReader;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Scanner;
import java.util.Locale;
public class ScanSum {
public static void main(String[] args) throws IOException {
Scanner s = null;
double sum = 0;
try {
s = new Scanner(new BufferedReader(new FileReader("D:/java-projects/HelloWorld/bin/usnumbers.txt")));
s.useLocale(Locale.US);
while (s.hasNext()) {
if (s.hasNextDouble()) {
sum += s.nextDouble();
} else {
s.next();
}
}
} finally {
s.close();
}
System.out.println(sum);
}
}
As you can see, I am using absolute path to the file I am reading from:
s = new Scanner(new BufferedReader(new FileReader("D:/java-projects/HelloWorld/bin/usnumbers.txt")));
The problem arises when I try to use the relative path:
s = new Scanner(new BufferedReader(new FileReader("usnumbers.txt")));
I get an error:
Exception in thread "main" java.lang.NullPointerException
at ScanSum.main(ScanSum.java:24)
The file usnumbers.txt is in the same directory as the ScanSum.class file:
D:/java-projects/HelloWorld/bin/ScanSum.class
D:/java-projects/HelloWorld/bin/usnumbers.txt
How could I solve this?
If aioobe#'s suggestion doesn't work for you, and you need to find out which directory the app is running from, try logging the following:
new File(".").getAbsolutePath()
From which directory is the class file executed? (That would be the current working directory and base directory for relative paths.)
If you simply launch the application from eclipse, the project directory will be the working directory, and you should in that case use "bin/usnumbers.txt".
The NullPointerException is due to the fact that new FileReader() expression is throwing a FileNotFoundException, and the variable s is never re-assigned a non-null value.
The file "usnumbers.txt" is not found because relative paths are resolved (as with all programs) relative to the current working directory, not one of the many entries on the classpath.
To fix the first problem, never assign a meaningless null value just to hush the compiler warnings about unassigned variables. Use a pattern like this:
FileReader r = new FileReader(path);
try {
Scanner s = new Scanner(new BufferedReader(r));
...
} finally {
r.close();
}
For the second problem, change directories to the directory that contains "usnumbers.txt" before launching java. Or, move that file to the directory from which java is run.
It must be a FileNotFoundException causing NPE in the finally block.
Eclipse, by default, executes the class with the project folder (D:/java-projects/HelloWorld in your case ) as the working directory. Put the usnumbers.txt file in that folder and try. Or change the working directory in Run Configuration -> Argument tab
Since your working directory is “D:/java-projects/HelloWorld”
#pdbartlett's id is great, But
String filePath = new File(".").getAbsolutePath()
will output "D:/java-projects/HelloWorld/." which is not easy to add your extra relative path like "filePath" + "/src/main/resources/" + FILENAME which located in resources folder.
I suggest with String filePath = new File("").getAbsolutePath() which return the project root folder
In Eclipse, you can also look under "Run Configurations->Than TAB "Classpath".
By default the absolut path is listed under "User Entries" in [icon] 'your.path' (default classpath)
Put the file in resources folder.
ClassLoader classLoader = getClass().getClassLoader();
String file1 = classLoader.getResource("myfile.csv").getPath();