It's fixed! Thanks to Edgar Boda.
I created a class that should read a text file and put that into an array:
private static String[] parts;
public static void Start() throws IOException{
InputStream instream = new FileInputStream("Storyline.txt");
InputStreamReader inputreader = new InputStreamReader(instream);
BufferedReader buffreader = new BufferedReader(inputreader);
int numberOfLines=0, numberOfActions;
String line = null, input="";
while((line=buffreader.readLine())!=null){
line=buffreader.readLine();
input+=line;
}
parts=input.split(";");
}
But, when I try and output the array, it only contains one string. The last from the file, that I put in.
Here's the file I read from:
0;0;
Hello!;
Welcome!To this.;
56;56;
So;
I think it's something in the loop; but trying to put parts[number] in there doesn't work... Any suggestions?
You want to read the whole file into an String first maybe:
String line = null;
String input = "";
while((line=buffreader.readLine())!=null){
input += line;
}
parts = input.split(";");
You are overwriting the string array parts in every iteration of your while loop, so that's why it only contains the last line.
To store the entire file contents, with fields split, you'll need a 2-dimensional array, not a 1-dimensional array. Assuming there are 5 lines in the file:
private static String[][] parts = new String[5][];
Then assign each split array to an element of parts each loop:
parts[i++]=line.split(";"); // Assuming you define "i" for the line number
Also, split by default discards trailing empty tokens. To retain them, use the two-arg overload of split that takes a limit parameter. Pass a negative number to retain all tokens.
parts[i++] = line.split(";", -1);
It will only contain the last line; you are reassigning parts every time:
parts = line.split(";");
This trashes the previous reference and reassigns a reference to a new array to it. A better way might be to use a StringBuilder and append the lines and then split later:
StringBuilder stringBuilder = new StringBuilder();
while((line=buffreader.readLine())!=null){
stringBuilder.append(line);
}
parts = stringBuilder.toString().split(";");
This way you will get everything you want in one array. If you want to split everything such that you have one array per line, you will need parts to be a two-dimensional array. But the drawback is that you will need to know how many lines will be there in the file. Instead, you can use List<String[]> to keep track of your arrays:
List<String[]> lineParts = new ArrayList<String[]>();
while((line=buffreader.readLine())!=null){
lineParts.add(line.split(";"));
}
Related
I am writing a program which will allow users to reserve a room in a hotel (University Project). I have got this problem where when I try and read data from the file and store it in an array I receive a NumberFormatException.
I have been stuck on this problem for a while now and cannot figure out where I am going wrong. I've read up on it and apparently its when I try and convert a String to a numeric but I cannot figure out how to fix it.
Any suggestions, please?
This is my code for my reader.
FileReader file = new FileReader("rooms.txt");
Scanner reader = new Scanner(file);
int index = 0;
while(reader.hasNext()) {
int RoomNum = Integer.parseInt(reader.nextLine());
String Type = reader.nextLine();
double Price = Double.parseDouble(reader.nextLine());
boolean Balcony = Boolean.parseBoolean(reader.nextLine());
boolean Lounge = Boolean.parseBoolean(reader.nextLine());
String Reserved = reader.nextLine();
rooms[index] = new Room(RoomNum, Type, Price, Balcony, Lounge, Reserved);
index++;
}
reader.close();
This is the error message
This is the data in my file which I am trying to read:
Change your while loop like this
while (reader.hasNextLine())
{
// then split reader.nextLine() data using .split() function
// and store it in string array
// after that you can extract data from the array and do whatever you want
}
You're trying to parse the whole line to Integer. You can read the whole line as a String, call
.split(" ")
on it. This will split the whole line into multiple values and put them into an array. Then you can grab each item from the array and parse separately as you intended.
Please avoid posting screenshots next time, use proper formatting and text so someone can easily copy your code or test data to IDE and reproduce the scenario.
Use next() instead of nextLine().
With Scanner one must use hasNextLine, nextLine, hasNext, next, hasNextInt, nextInt etcetera. I would do it as follows:
Using Path and Files - the newer more general classes i.o. File.
Files can read lines, here I use Files.lines which gives a Stream of lines, a bit like a loop.
Try-with-resources: try (AutoCloseable in = ...) { ... } ensures that in.close() is always called implicitly, even on exception or return.
The line is without line ending.
The line is split into words separated by one or more spaces.
Only lines with at least 6 words are handled.
Create a Room from the words.
Collect an array of Room-s.
So:
Path file = Paths.get("rooms.txt");
try (Stream<String> in = Files.lines(file)) {
rooms = in // Stream<String>
.map(line -> line.split(" +")) // Stream<String[]>
.filter(words -> words.length >= 6)
.map(words -> {
int roomNum = Integer.parseInt(words[0]);
String type = words[1];
double price = Double.parseDouble(words[2]);
boolean balcony = Boolean.parseBoolean(words[3]);
boolean lounge = Boolean.parseBoolean(words[4]);
String reserved = words[5];
return new Room(roomNum, type, price, balcony, lounge, reserved);
}) // Stream<Room>
.toArray(Room[]::new); // Room[]
}
For local variables use camelCase with a small letter in front.
The code uses the default character encoding of the system to convert the bytes in the file to java Unicode String. If you want all Unicode symbols,
you might store your list as Unicode UTF-8, and read them as follows:
try (Stream<String> in = Files.lines(file, StandardCharsets.UTF_8)) {
An other issue is the imprecise floating point double. You might use BigDecimal instead; it holds a precision:
BigDecimal price = new BigDecimal(words[2]);
It is however much more verbose, so you need to look at a couple of examples.
I'm coding in Java and I want to split my string. I want to split it at.
/* sort */
Yes I plan to split a .java file that I have read as a string so I need it to include "/* sort */". I'm creating a code that sorts Arrays that are predefined in java class file.
Exactly that and do another split at
}
and then I wanted help how to go about splitting up the array since I'll be left with
an example would be this
final static String[] ANIMALS = new String[] /* sort */ { "eland", "antelope", "hippopotamus"};
My goal would be to sort that Array inside a .java file and replace it. This is my current code
private void editFile() throws IOException {
//Loads the whole Text or java file into a String
try (BufferedReader br = new BufferedReader(new FileReader(fileChoice()))) {
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
sb.append(System.lineSeparator());
line = br.readLine();
}
everything = sb.toString();
}
arrayCutOff = everything.split("////* sort *////");
for(int i = 0; i < arrayCutOff.length; i++){
System.out.println(arrayCutOff[i]);
}
}
This basically reads the whole .txt or .java file completely with the exact same formatting into one string. I planned to split it at /* sort */ and sort the array inside but I realized if I did that I probably can't replace it.
Considered your're using java 8 you might go this direction:
private void editFile() throws IOException {
List<String> lines = Files.readAllLines(Paths.get(fileChoice()));
String content = lines.stream().collect(Collectors.joining(System.lineSeparator()));
Stream.of(content.split(Pattern.quote("/* sort */"))).forEach(System.out::println);
}
However, the trick you're asking for is Pattern.quote, which dates back Java 5. It'll qoute a literal so it can be used as a literal in regExs and is a bit more convenient (and reliable I think) than wrestling around with backslashes...
I have the following issue: I am trying to parse a .csv file in java, and store specifically 3 columns of it in a 2 Dimensional array. The Code for the method looks like this:
public static void parseFile(String filename) throws IOException{
FileReader readFile = new FileReader(filename);
BufferedReader buffer = new BufferedReader(readFile);
String line;
String[][] result = new String[10000][3];
String[] b = new String[6];
for(int i = 0; i<10000; i++){
while((line = buffer.readLine()) != null){
b = line.split(";",6);
System.out.println("ID: "+b[0]+" Title: "+b[3]+ "Description: "+b[4]); // Here is where the outofbounds exception occurs...
result[i][0] = b[0];
result[i][1] = b[3];
result[i][2] = b[4];
}
}
buffer.close();
}
I feel like I have to specify this: the .csv file is HUGE. It has 32 columns, and (almost) 10.000 entries (!).
When Parsing, I keep getting the following:
XXXXX CHUNKS OF SUCCESFULLY EXTRACTED CODE
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException:3
at ParseCSV.parseFile(ParseCSV.java:24)
at ParseCSV.main(ParseCSV.java:41)
However, I realized that SOME of the stuff in the file has a strange format e.g. some of the texts inside it for instance have newlines in them, but there is no newline character involved in any way. However, if I delete those blank lines manually, the output generated (before the error message is prompted) adds the stuff to the array up until the next blank line ...
Does anyone have an idea how to fix this? Any help would be greately appreciated...
Your first problem is that you probably have at least one blank line in your csv file. You need to replace:
b = line.split(";", 6);
with
b = line.split(";");
if(b.length() < 5){
System.err.println("Warning, line has only " + b.length() +
"entries, so skipping it:\n" + line);
continue;
}
If your input can legitimately have new lines or embedded semi-colons within your entries, that is a more complex parsing problem, and you are probably better off using a third-party parsing library, as there are several very good ones.
If your input is not supposed to have new lines in it, the problem probably is \r. Windows uses \r\n to represent a new line, while most other systems just use \n. If multiple people/programs edited your text file, it is entirely possible to end up with stray \r by themselves, which are not easily handled by most parsers.
A way to easily check if that's your problem is before you split your line, do
line = line.replace("\r","").
If this is a process you are repeating many times, you might need to consider using a Scanner (or library) instead to get more efficient text processing. Otherwise, you can make do with this.
When you have new lines in your CSV file, after this line
while((line = buffer.readLine()) != null){
variable line will have not a CSV line but just some text without ;
For example, if you have file
column1;column2;column
3 value
after first iteration variable line will have
column1;column2;column
after second iteration it will have
3 value
when you call "3 value".split(";",6) it will return array with one element. and later when you call b[3] it will throw exception.
CSV format has many small things, to implement which you will spend a lot of time. This is a good article about all possible csv examples
http://en.wikipedia.org/wiki/Comma-separated_values#Basic_rules_and_examples
I would recommend to you some ready CSV parsers like this
https://commons.apache.org/proper/commons-csv/apidocs/org/apache/commons/csv/CSVParser.html
String's split(pattern, limit) method returns an array sized to the number of tokens found up to the the number specified by the limit parameter. Limit is the maximum, not the minimum number of array elements returned.
"1,2,3" split with (",", 6) with return an array of 3 elements: "1", "2" and "3".
"1,2,3,4,5,6,7" will return 6 elements: "1", "2", "3", "4", "5" and ""6,7" The last element is goofy because the split method stopped splitting after 5 and returned the rest of the source string as the sixth element.
An empty line is represented as an empty string (""). Splitting "" will return an array of 1 element, the empty string.
In your case, the string array created here
String[] b = new String[6];
and assigned to b is replaced by the the array returned by
b = line.split(";",6);
and meets it's ultimate fate at the hands of the garbage collector unseen and unloved.
Worse, in the case of the empty lines, it's replaced by a one element array, so
System.out.println("ID: "+b[0]+" Title: "+b[3]+ "Description: "+b[4]);
blows up when trying to access b[3].
Suggested solution is to either
while((line = buffer.readLine()) != null){
if (line.length() != 0)
{
b = line.split(";",6);
System.out.println("ID: "+b[0]+" Title: "+b[3]+ "Description: "+b[4]); // Here is where the outofbounds exception occurs...
...
}
or (better because the previous could trip over a malformed line)
while((line = buffer.readLine()) != null){
b = line.split(";",6);
if (b.length() == 6)
{
System.out.println("ID: "+b[0]+" Title: "+b[3]+ "Description: "+b[4]); // Here is where the outofbounds exception occurs...
...
}
You might also want to think about the for loop around the while. I don't think it's doing you any good.
while((line = buffer.readLine()) != null)
is going to read every line in the file, so
for(int i = 0; i<10000; i++){
while((line = buffer.readLine()) != null){
is going to read every line in the file the first time. Then it going to have 9999 attempts to read the file, find nothing new, and exit the while loop.
You are not protected from reading more than 10000 elements because the while loop because the while loop will read a 10001th element and overrun your array if there are more than 10000 lines in the file. Look into replacing the big array with an arraylist or vector as they will size to fit your file.
Please check b.length>0 before accessing b[].
I'm trying to read a data file and save the different variables into an array list.
The format of the data file looks a little like this like this
5003639MATH131410591
5003639CHEM434111644
5003639PSYC230110701
Working around the bad formatting of the data file, I added commas to the different sections to make a split work. The new text file created looks something like this
5,003639,MATH,1314,10591
5,003639,CHEM,4341,11644
5,003639,PSYC,2301,10701
After creating said file, I tried to save the information into an array list.
The following is the snippet of trying to do this.
FileReader reader3 = new FileReader("example.txt");
BufferedReader br3 = new BufferedReader(reader3);
while ((strLine = br3.readLine())!=null){
String[] splitOut = strLine.split(", ");
if (splitOut.length == 5)
list.add(new Class(splitOut[0], splitOut[1], splitOut[2], splitOut[3], splitOut[4]));
}
br3.close();
System.out.println(list.get(0));
The following is the structure it is trying to save into
public static class Class{
public final String recordCode;
public final String institutionCode;
public final String subject;
public final String courseNum;
public final String sectionNum;
public Class(String rc, String ic, String sub, String cn, String sn){
recordCode = rc;
institutionCode = ic;
subject = sub;
courseNum = cn;
sectionNum = sn;
}
}
At the end I wanted to print out one of the variables to see that it's working but it gives me an IndexOutOfBoundsException. I wanted to know if I'm maybe saving the info incorrectly, or am I perhaps trying to get it to print out incorrectly?
You have a space in your split delimiter specification, but no spaces in your data.
String[] splitOut = strLine.split(", "); // <-- notice the space?
This will result in a splitOut array of only length 1, not 5 like you expect.
Since you only add to the list when you see a length of 5, checking the list for the 0th element at the end will result in checking for the first element of an empty list, hence your exception.
If you expect your data to have a comma or a space separating the characters then you would alter the split line to be:
String[] splitOut = strLine.split("[, ]");
The split takes a regular expression as an argument.
Rather than artificially adding commas I would look at String.substring in order to cut the line you have read into pieces. For example:
while ((strLine = br3.readLine())!=null) {
if (strLine.length() != 20)
throw new BadLineException("line length is not valid");
list.add(new Class(strLine.substring(0,1), strLine.substring(1,7), strLine.substring(7,11), strLine.substring(11,15), strLine.substring(15,19)));
}
[ Untested: my numbers might be out because I a bit knacked, but you get the idea ]
Below is how i count the number of lines in a text file. Just wondering is there any other methods of doing this?
while(inputFile.hasNext()) {
a++;
inputFile.nextLine();
}
inputFile.close();
I'm trying to input data into an array, i don't want to read the text file twice.
any help/suggestions is appreciated.
thanks
If you are using java 7 or higher version you can directly read all the lines to a List using readAllLines method. That would be easy
readAllLines
List<String> lines = Files.readAllLines(Paths.get(fileName), Charset.defaultCharset());
Then the size of the list will return you number of lines in the file
int noOfLines = lines.size();
If you are using Java 8 you can use streams :
long count = Files.lines(Paths.get(filename)).count();
This will have good performances and is really expressive.
The downside (compared to Thusitha Thilina Dayaratn answer) is that you only have the line count.
If you also want to have the lines in a List, you can do (still using Java 8 streams) :
// First, read the lines
List<String> lines = Files.lines(Paths.get(filename)).collect(Collectors.toList());
// Then get the line count
long count = lines.size();
If you just want to add the data to an array, then I append the new values to an array. If the amount of data you are reading isn't large and you don't need to do it often that should be fine. I use something like this, as given in this answer: Reading a plain text file in Java
BufferedReader fileReader = new BufferedReader(new FileReader("path/to/file.txt"));
try {
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
sb.append(System.lineSeparator());
line = br.readLine();
}
String everything = sb.toString();
} finally {
br.close();
}
If you are reading in numbers, the strings can be converted to numbers, say for integers intValue = Integer.parseInt(text)
I do not have enough reputation to comment but #superbob answer is almost perfect, indeed you must ensure to pass Charset.defaultCharset() as 2nd parameter like :
Files.lines(file.toPath(), Charset.defaultCharset()).count()
That's because Files.lines used UTF-8 by default and then using as it is on non default UTF-8 system can produce java.nio.charset.MalformedInputException.