I am creating a stock market simulator (beginner) and I made a .txt file to save the stock symbol and name within a file. I am having an issue where my code is unable to find the file on my desktop.
public static void load() throws FileNotFoundException {
File file = new File("/Users/dhruvchaudhari/Desktop/stocks.txt");
Scanner scan = new Scanner(file);
while ((scan.hasNextLine())) {
System.out.println(scan.nextLine());
}
}
The error it is throwing is as such
java.io.FileNotFoundException: /Users/*username*/Desktop/stocks.txt (No such file or directory)
I'm on Mac and I checked the directory for the file directory and it should be correct. Any suggestions?
You can check the current working directory to confirm the path of your file by adding System.out.println("Working Directory = " + System.getProperty("user.dir"));
this will return the path you can debug this to get the idea of path in your application.
Also you can add read the file if its not there the code will create it for so you can add your metadata into the generated file.
By using this approach I hope you can move ahead.
public static void load() throws IOException {
File yourFile = new File(path);
yourFile.createNewFile(); // if file already exists will do nothing
Scanner scan = new Scanner(yourFile);
while ((scan.hasNextLine())) {
System.out.println(scan.nextLine());
}
}
Obviously your path is wrong or the file doesn't exist. You can use the if statement to determine whether the file exists first, and create the file when it does not exist.
Related
The way I go is
Resource iconHomeResource = new ClassPathResource("/assets/icons/icons8-home-16.png");
//print iconHomeResource.exists() IS TRUE
File iconHome = iconHomeResource.getFile() //throws FileNotFoundException.
In the past I used something like this.
/** This Work inside IDE but not in production*/
public File loadEmployeesWithSpringInternalClass()
throws FileNotFoundException {
return ResourceUtils.getFile(
"classpath:data/employees.dat");
}
I read some similiar Questions/Answeres here on SoF but not of them worked for me.
I'm working on a program that reads from a file with a custom extension I made. The idea is that an error report is created every time a file is read. The error report must be in whatever folder the source file was called from. The error file is a copy of the source file, but it has a line number at the beginning of each line and indicates at the end of the line if an error occurred at that line.
(I'm not trying to set up the numbering on this question, this question is just about creating the copy)
So for example, when I call my program from the command prompt:
C:\MyLocation>java =jar myJavaProgram.jar myFileToRead.CustomExtension
Asides from reading the file, it should also create a copy at the same location called myFileToRead-ErrorReport.txt
Additionally: If the source file has no extension, I have to assume that it's still the correct extension, so there won't always be a '.myCustomExtension' segment to replace into .txt
The problem is that I don't know how to grab the file name, because it's coming from the args list of the main method. I am using the following to read the file
public static void main(String[] args) throws FileNotFoundException {
try{
File inputFile = new File(args[0]);
Scanner sc = new Scanner(inputFile);
while(sc.hasNext()){
System.out.println(sc.nextLine());
}
} catch (FileNotFoundException ex) {
System.out.println(ex.getMessage());
System.out.println("File not found.");
}
}
So how can I get that file name to make something like
File errorReport = new File("./" + inputFileName + ".txt"); ?
First the code. The explanations appear after the code.
public static void main(String[] args) {
if (args.length < 1) {
System.out.println("ERROR: Missing filename argument.");
}
else {
String filename = args[0];
if (filename.length() == 0) {
System.out.println("ERROR: Empty filename argument.");
}
else {
if (!filename.endsWith(".CustomExtension")) {
filename += ".CustomExtension";
}
String name = filename.substring(0, filename.indexOf(".CustomExtension"));
name += "-ErrorReport.txt";
File inputFile = new File(filename);
File directory = inputFile.getParentFile();
File errorReport = new File(directory, name);
System.out.println(errorReport.getAbsolutePath());
}
}
}
I make it a habit of checking the parameters. Hence I first check that the file name was supplied. If it was, then I check that it is not an empty string. Note that I have omitted some checks, for example checking whether the named file exists and is readable.
You wrote in your question that the file name argument may or may not include the .CustomExtension. Hence I check whether the supplied name ends with the required extension and append it if necessary. Now, since I know what the file name ends with, that means that the required part of the name is everything up to the extension and that's what the call to substring() gives me.
Once I have the required name, I just append the part that you want to append, i.e. -ErrorReport.txt.
Method getParentFile() in class java.io.File returns the directory that the file is located in. Hence I have the directory that the input file is in. Finally I can create the error report file in the same directory as the input file and with the desired file name. For that I use the constructor of class java.io.File that takes two parameters. Read the javadoc for details.
Note that creating a File object does not create the file. Creating an object to write to the file does, for example FileWriter or OutputStreamWriter.
Here is the code example to create a file, with filename passed from cmd line as argument and to get the same file name :
Class Demo{
public static void main(String[]args){
String path ="<path of file>"
String name= args[0];
File f = new File(path+name+".txt");
f.createNewFile(); //create file
System.out.println(f.getName()); // will give you the file name
}
}
cmd line : java -cp . Demo.java <filename>
Note : '.' used in the cmd if your class file is present in current dir
You can refer the code and modify to suit your requirement.
Hope this is what you are looking for.
The following program has the purpose of creating a directory,
folderforallofmyjavafiles.mkdir();
and making a file to go inside that directory,
File myfile = new File("C:\\Users\\username\\Desktop\\folderforallofmyjavafiles\\test.txt");
There are two problems though. One is that it says the directory is being created at the desktop, but when checking for the directory, it is not there. Also, when creating the file, I get the exception
ERROR: java.io.FileNotFoundException: folderforallofmyjavafiles\test.txt (The system cannot find the path specified)
Please help me resolve these issues, here is the full code:
package mypackage;
import java.io.*;
public class Createwriteaddopenread {
public static void main(String[] args) {
File folderforallofmyjavafiles = new File("C:\\Users\\username\\Desktop");
try {
folderforallofmyjavafiles.mkdir(); //Creates a directory (mkdirs makes a directory)
if (folderforallofmyjavafiles.isDirectory() == true) {
System.out.println("Folder created at " + "'" + folderforallofmyjavafiles.getPath() + "'");
}
} catch (Exception e) {
System.out.println("Not working...?");
}
File myfile = new File("C:\\Users\\username\\Desktop\\folderforallofmyjavafiles\\test.txt");
//I even tried this:
//File myfile = new File("folderforallofmyjavafiles/test.txt");
//write your name and age through the file
try {
PrintWriter output = new PrintWriter(myfile); //Going to write to myfile
//This may throw an exception, so I always need a try catch when writing to a file
output.println("myname");
output.println("myage");
output.close();
System.out.println("File created");
} catch (IOException e) {
System.out.printf("ERROR: %s\n", e); //e is the IOException
}
}
}
Thank you so much for helping me out, I really appreciate it.
:)
You're creating the Desktop folder in the C:\Users\username folder. If you check the return value of mkdir, you'd notice it's false because the folder already exists.
How would the system know that you want a folder named folderforallofmyjavafiles unless you tell it so?
So, you didn't create the folder, and then you try to create a file in the (nonexistent) folder, and Java tells you the folder doesn't exist.
Agreed that it's a bit obscure, using a FileNotFoundException, but the text does say "The system cannot find the path specified".
Update
You're probably confused about the variable name, so let me say this. The following are all the same:
File folderforallofmyjavafiles = new File("C:\\Users\\username\\Desktop");
folderforallofmyjavafiles.mkdir();
File x = new File("C:\\Users\\username\\Desktop");
x.mkdir();
File folderToCreate = new File("C:\\Users\\username\\Desktop");
folderToCreate.mkdir();
File gobbledygook = new File("C:\\Users\\username\\Desktop");
gobbledygook.mkdir();
new File("C:\\Users\\username\\Desktop").mkdir();
I'm making a program where I have to make a file and then deserialize the object in that file. When I name the file something, such as "contacts.dat", I get a FileNotFoundException.
The code is below:
public static void main(String[] args) {
String inputstring = Input.getString("Please enter the name of the file containing the contacts: ");
TreeMap< String, Contact > contactlist = null;
ObjectInputStream in;
try {
in = new ObjectInputStream(new BufferedInputStream(new FileInputStream(inputstring)));
contactlist = (TreeMap< String, Contact >) in.readObject();
in.close();
}
catch(ClassNotFoundException | EOFException emptyexcptn) {
System.out.println("The file provided is currently empty.");
contactlist = new TreeMap< String, Contact >();
}
catch(IOException ioexcptn) {
ioexcptn.printStackTrace(System.out);
System.out.println("Error reading file: " + inputstring);
System.exit(1);
}
Here's what the exception prints:
java.io.FileNotFoundException: contacts.dat (The system cannot find the file specified)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(FileInputStream.java:195)
at java.io.FileInputStream.(FileInputStream.java:138)
at java.io.FileInputStream.(FileInputStream.java:93)
at UnitEight.AssignmentEight.main(AssignmentEight.java:16)
Error reading file: contacts.dat
Your argument to new FileInputStream() is String inputstring = Input.getString("Please enter the name of the file containing the contacts: ");...if Input.getString returns the path for the file then you are pointing to the wrong path anyway.
Print the result of Input.getString()...if any and that would give you a clue what's going on there.
From the API docs -
Constructor Detail
FileInputStream
public FileInputStream(String name) throws FileNotFoundException
Creates a FileInputStream by opening a connection to an actual file, the file named by the path name name in the file system. A new FileDescriptor object is created to represent this file connection.
First, if there is a security manager, its checkRead method is called with the name argument as its argument.
If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading then a FileNotFoundException is thrown.
Parameters:name - the system-dependent file name.Throws:FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.SecurityException - if a security manager exists and itscheckRead method denies read access to the file.
To summarize in to a working example:
When you are using the FileInputStream(String filename), try it by specifying the full (absolute) path to the file so your program can find it. Ex: if your text.dat file was on a shared drive Z: your String you would have to pass as a parameter to the constructor would be
"Z:\\text.dat" instead of using an OS specific slash character it is better to use File.separator in the above example it would look like "Z" + File.separator + "text.dat".
I am very new at java and my be missing something very basic. When i run my code i am trying to add value to accounts created in the code. When i try to run the code i recieve an error that a file cannot be found, but i thought that the file was created inside the code.
import java.util.Scanner;
import java.io.File;
import java.io.IOException;
class DoPayroll
{
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();
}
}
once run i recieve the following error
Exception in thread "main" java.io.FileNotFoundException: EmployeeInfo.txt (No such file or directory)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:106)
at java.util.Scanner.<init>(Scanner.java:636)
at DoPayroll.main(jobexe.java:11)
i thought that in the above code using new Scanner(new File("EmployeeInfo.txt") would create the new file once i input a value. Please give me a simple solution and an explanation.
It will create a new file when you write to it. However to read from it, it must already exist. You might like to check it exists with
File file = new File("EmployeeInfo.txt");
if (file.exists()) {
Scanner diskScanner = new Scanner(file);
for (int empNum = 1; empNum <= 3; empNum++)
payOneEmployee(diskScanner);
}
The File object can't find the filename you've passed. You either need to pass the full path of EmployeeInfo.txt to new File(...) or make sure current working directory is the directory that contains this file.
The File constructor does not create a file. Rather, it creates the information in Java needed to access a file on disk. You'd have to actually do file IO in Java using the created File for a new file to be created.
The Scanner constructor requires an existing File. So you need a full path to the real, valid location of EmployeeInfo.txt or to create that file using File I/O first. This tutorial on I/O in Java will help.
You are mistaking instantiating an instance of class File with actually writing a temp file to Disk. Take this line
Scanner diskScanner =
new Scanner(new File("EmployeeInfo.txt"));
And replace it with this
File newFile = File.createTempFile("EmployeeInfo", ".txt");
Scanner diskScanner = new Scanner(newFile);
Edit: Peter makes a good point. I'm face palming right now.
You thought wrong :D A Scanner needs a existing file, which seems quite logical as it reads values and without a existing file its difficult to read. The documentation also states that:
Throws:
FileNotFoundException - if source is not found
So, in short: You must provide a readable, existing file to a scanner.
As the other answer explain, the file is not created just by using new File("EmployeeInfo.txt").
You can check is the file exists using
File file = new File("EmployeeInfo.txt");
if(file.exists()) {
//it exists
}
or you can create the file (if it doesn't exists yet) using
file.createNewFile();
that method returns true if the file was created and false if it already existed.