I have Loader class where I load txt file into BufferedReader from resources and return this field. I use this method but it acts really strange(for me). When I don't put
String str = bufferReader.readLine(); after
bufferReader = new BufferedReader(fileReader);
(in Loader class) than bufferReader in another class is empty, and readLine() returns null. When I write that piece of code in Loader class, I can read each line from txt, except the 1. one which is read in Loader class. Also, I can't read last line if I dont put enter at the end.
public BufferedReader loadFromFileToBufferReader(String fileName) {
ClassLoader classLoader = getClass().getClassLoader();
System.out.print(getClass().getClassLoader().getResource("resources/" + fileName));
File file = new File(classLoader.getResource("resources/" + fileName).getFile());
BufferedReader bufferReader = null;
try (FileReader fileReader = new FileReader(file)) {
bufferReader = new BufferedReader(fileReader);
String str = bufferReader.readLine();
} catch (IOException e) {
System.err.println("Something went terribly wrong with file reading");
}
return bufferReader;
}
and usage:
public Database() {
productsInDatabse = new ArrayList<>();
codesList = new ArrayList<>();
loader = new LoadFromFile();
BufferedReader output = loader.loadFromFileToBufferReader("database.txt");
Product product;
String line;
String[] array;
try {
line = output.readLine();
while (line != null) {
You should paste your code here because it's hard to deduce all the possible causes of this without seeing the code on 100% but I am guessing you have it the same file open at the same time from multiple sources without closing it before from one? Could be literally millions of little things, just telling you how the same error happened to me.
Related
I have been trying to make a string validator but some characters in the input have some swedish characters which I haven't been able to parse. I have been going mad about this. Tried everything I found on the internet. Can anybody please help me out?
This is the logic for reading the file. I have been trying to parse it.
I haven't been able to specifically parse this word: leverantör. It's parsed as leverant�r.
public String processFile(MultipartFile file) throws IOException, FormatNotFoundException {
// TODO Auto-generated method stub
BufferedReader r = new BufferedReader(new InputStreamReader(file.getInputStream()));
String output;
while((output = r.readLine())!=null ) {
logger.debug(output);
InputStream is= new ByteArrayInputStream(output.getBytes(StandardCharsets.UTF_8));
StringBuilder textBuilder = new StringBuilder();
try (
Reader reader = new BufferedReader(new InputStreamReader
(is, Charset.forName(StandardCharsets.UTF_8.name())))) {
int c = 0;
while ((c = reader.read()) != -1) {
textBuilder.append((char) c);
}
}
logger.debug(textBuilder.toString());
System.out.println(textBuilder.toString());
}
return "File read.";
}
So whenever I try to append a new line using a StringBuilder, I can't get a new line whatsoever, I tried:
errorMessage.append(System.getProperty("line.separator"));
errorMessage.append(System.getProperty("\n"));
errorMessage.append(System.getProperty("\r\n"));
errorMessage.append(System.getProperty("line.separator"));
basically everything within the first 3 pages of google results, it's so frustrating. I am implementing it in a for loop like this : idk if it helps, but any suggestions are appreciated.
public String getIDs(HashMap<String,List<Integer>> errorMap ){
StringBuilder errorMessage = new StringBuilder();
for (String state:errorMap.keySet()){
List<Integer> listofId = errorMap.get(state);
if (listofId){
StringBuilder listOfIds = new StringBuilder();
for (Integer id :listofId) {
listOfIds.append(id.toString()+' , ')
}
errorMessage.append(state +" Trades: " +listOfIds.toString())
errorMessage.append("\n")
}
}
return errorMessage.toString();
}
Use
errorMessage.append("\n");
Instead of
errorMessage.append(System.getProperty("\n"));
You should directly be using builder.append("\n"). \n is not a property.
Also append method returns builder object itself (Builder pattern). So you can easily do builder.append("\n").append("text1").append("\n").append("text2").....
I have written a groovy script to read a huge file line by line.
I currently am using boilerplate code as follows
File hugeFile = new File(filePath)
if (hugeFile.exists()) {
hugeFile.eachLine {line ->
//some process
}
}
My question is how do I find out if the "eachLine" is using a BufferedReader to be memory efficient ?
Give it a shot to see if it can handle big files.
And check the source at github:
public static <T> T eachLine(Reader self, int firstLine, #ClosureParams(value=FromString.class,options={"String","String,Integer"}) Closure<T> closure) throws IOException {
BufferedReader br;
int count = firstLine;
T result = null;
if (self instanceof BufferedReader)
br = (BufferedReader) self;
else
br = new BufferedReader(self);
...
}
I have my uni assignment and it's only very basic coding but I have to do
A user shall be able to store records to a file. On start-up a user shall be able to select a file of records and load these into the program.
I am having trouble with this as it will save but once I close the program and re-open it they are gone, any ones help is appreciated.
This is what I have so far:
private void Save_Click(object sender, EventArgs e)
{
SaveToFile(records, file);
}
private void SaveToFile(List<Client> records, string file)
{
//File.WriteAllText(file, String.Empty);
StreamWriter writer = new StreamWriter(file);
StreamReader reader = new StreamReader(file);
try
{
AddMember();
for (int i = 0; i < records.Count; i++)
{
writer.WriteLine(records[i].WriteToFile());
}
writer.Close();
}
catch (IOException z)
{
MessageBox.Show("Error" + z);
}
}
Before closing the StreamWriter you should call Flush() method. Flush() Clears all buffers for the current writer and causes any buffered data to be written to the underlying stream.
reader.clos();
you forgot this
This is just a guess, but it sounds like you might be overwriting the file when you start the program.
In your SaveToFile method, you have the following two lines at the start:
StreamWriter writer = new StreamWriter(file);
StreamReader reader = new StreamReader(file);
The first one will create a new file with the name in file. The second one isn't needed if you're not doing any reading from the file.
Now, if you have a similar block of code in somewhere else in your program that is executed before the SaveToFile method is called, it will overwrite the file (and since you most likely don't write anything in that earlier part of the code, you're left with a blank file).
To prevent this, there are two suggestions I'll offer:
Only create a StreamWriter when you are going to be writing to the file. Any other times you create a StreamWriter, you will be overwriting the existing file.
If you don't want to overwrite the file, you can use the overload of the constructor that takes a second parameter (a boolean) to indicate whether or not to append new data to the file:
StreamWriter writer = new StreamWriter(file, true);
Additionally, I'd suggest getting to know and use using blocks, as this will take care of closing and flushing the StreamWriter (and its underlying stream) for you, even if an exception occurs and is unhandled:
private void SaveToFile(List<Client> records, string file)
{
try
{
AddMember();
// If you don't want to append but overwrite, use:
// using (StreamWriter writer = new StreamWriter(file))
using (StreamWriter writer = new StreamWriter(file, append))
{
for (int i = 0; i < records.Count; i++)
{
writer.WriteLine(records[i].WriteToFile());
}
}
}
catch (IOException z)
{
MessageBox.Show("Error" + z);
}
}
I am currently making an "app launcher" which reads a text file line by line. Each line is a path to a useful program somewhere else on my pc. A link label is automatically made for each path (i.e. each line) in the text file.
I would like the .Text property of the link label to be an abbreviated form of the path (i.e. just the file name, not the whole path). I have found out how to shorten the string in this way (so far so good !)
However, I would also like to store the full path somewhere - as this is what my linklabel will need to link to. In Javascript I could pretty much just add this property to linklabel like so: mylinklabel.fullpath=line; (where line is the current line as we read through the text file, and fullpath is my "custom" property that I would like to try and add to the link label. I guess it needs declaring, but I am not sure how.
Below is the part of my code which creates the form, reads the text file line by line and creates a link label for the path found on each line:
private void Form1_Load(object sender, EventArgs e) //on form load
{
//System.Console.WriteLine("hello!");
int counter = 0;
string line;
string filenameNoExtension;
string myfile = #"c:\\users\matt\desktop\file.txt";
//string filenameNoExtension = Path.GetFileNameWithoutExtension(myfile);
// Read the file and display it line by line.
System.IO.StreamReader file = new System.IO.StreamReader(myfile);
while ((line = file.ReadLine()) != null)
{
//MessageBox.Show(line); //check whats on each line
LinkLabel mylinklabel = new LinkLabel();
filenameNoExtension = Path.GetFileNameWithoutExtension(line); //shortens the path to just the file name without extension
mylinklabel.Text = filenameNoExtension;
//string fullpath=line; //doesn't work
//mylinklabel.fullpath=line; //doesn't work
mylinklabel.Text = filenameNoExtension; //displays the shortened path
this.Controls.Add(mylinklabel);
mylinklabel.Location = new Point(0, 30 + counter * 30);
mylinklabel.AutoSize = true;
mylinklabel.VisitedLinkColor = System.Drawing.Color.White;
mylinklabel.LinkColor = System.Drawing.Color.White;
mylinklabel.Click += new System.EventHandler(LinkClick);
counter++;
}
file.Close();
}
So, how can I store a full path as a string inside the linklabel for use in my onclick function later on?
You could derive a new custom class or you could use a secondary data store for your additional info the easiest solution would be to use a dictionary.
dictonary<string,string> FilePaths = new dictonary<string,string>();
private void Form1_Load(object sender, EventArgs e) //on form load
{
...
FilePath[filenameNoExtension] = line;
}
You Can Access the Path
FilePath[mylinklabel.Tex]
One option you have is to have a method that truncates your string (and even adds "..."). You can then store the full path in the Tag property of the Linklabel. And here's an example of the first part (truncating the text).
public static string Truncate(this string s, int maxLength)
{
if (string.IsNullOrEmpty(s) || maxLength <= 0)
return string.Empty;
else if (s.Length > maxLength)
return s.Substring(0, maxLength) + "...";
else
return s;
}
Hope that helps some