Develop Reference

Scanning a text file into an array and omitting one specified line

I'm a beginner and need some help. I'm trying to scan a text file into an array line by line, but omitting one line. My text file is
i am
you are
he is
she is
it is
I want to create a method that will scan this and put elements into an array with an exception for one line (that is chosen by entering the String as a parameter for the method). Then erase the original text file and print there the created array (without that one deleted line). Sorry, I suck at explaining.
I have tried this:
public static void deleteLine(String name, String line) throws IOException {
String sc = System.getProperty("user.dir") + new File("").separator;
FileReader fr = new FileReader(sc + name + ".txt");
Scanner scan = new Scanner(fr);
int n = countLines(name); // a well working method returning the number if lines in the file (here 5)
String[] listArray = new String[n-1];
for (int i = 0; i < n-1; i++) {
if (scan.hasNextLine() && !scan.nextLine().equals(line))
listArray[i] = scan.nextLine();
else if (scan.hasNextLine() && scan.nextLine().equals(line))
i--;
else continue;
}
PrintWriter print = new PrintWriter(sc + name + ".txt");
print.write("");
for (int i = 0; i < n-2; i++) {
print.write(listArray[i] + "\n");
}
print.close()
}
I get an error "Line not found" when I enter: deleteLine("all_names","you are") (all_names is the name of the file). I'm sure the problem lies in the for-loop, but I have no idea why this doesn't work. :(
//SOLVED//
This code worked after all. Thanks for answers!
public static void deleteLine(String name, String line) throws IOException{
String sc = System.getProperty("user.dir") + new File("").separator;
FileReader fr = null;
fr = new FileReader(sc+name+".txt");
Scanner scan = new Scanner(fr);
int n = LineCounter(name);
String[] listArray = new String[n-1];
for (int i = 0; i < n-1; i++) {
if (scan.hasNextLine()) {
String nextLine = scan.nextLine();
if (!nextLine.equals(line)) {
listArray[i] = nextLine;
}
else i--;
}
}
PrintWriter print = new PrintWriter(sc+name+".txt");
print.write("");
for(int i=0;i<n-1;i++){
print.write(listArray[i]+System.lineSeparator());
}
print.close();
}

You are reading the lines twice scan.nextLine() while comparing and because of that you run out of the lines.
Replace your loop with this one or similar
for (int i = 0; i < n; i++) {
if (scan.hasNextLine()) {
String nextLine = scan.nextLine();
if (nextLine.equals(line)) {
listArray[i] = nextLine;
}
}
}

Have a look at how you are comparing String objects. You should use the equals method to compare a String's content. Using operators like == and != compares if the String objects are identical.
Now after using equals correctly have a look at how you are using nextLine. Check its Javadoc

I feel LineCounter(name) works because you did not put a ".txt" there. Try removing the ".txt" extension from the file name in the Filereader and Printwriter objects and see if it works. Usually in windows, the extension is not a part of the file name.

Here's an alternative (easier) solution to do what you want, using easier to understand code. (I think)
Also it avoids multiple
loops, but uses a single Java 8 stream to filter instead.
public static void deleteLine(String name, String line) throws IOException {
List<String> lines = Files.readAllLines(Paths.get(name));
lines = lines.stream().filter(v -> !v.equals(line)).collect(Collectors.toList());
System.out.println(lines);
// if you want the String[] - but you don't need it
String[] linesAsStringArr = new String[lines.size()];
linesAsStringArr = lines.toArray(linesAsStringArr);
// write the file using our List<String>
Path out = Paths.get("output.txt"); // or another filename you dynamically create
Files.write(out, lines, Charset.forName("UTF-8"));
}

Having trouble with parsing csv files in Java

I'm trying to parse a folder of csv files (balance sheets), and have everythings gone smoothly up until I tried to separate the row names from the values.
It looks like the last cell on the previous row is combining with the first cell (the row name in column A) in the next row.
File path = new File("/Users/Zack/Desktop/JavaDB/BALANCESHEETS");
for(File file: path.listFiles()) {
if (file.isFile()) {
String fileName = file.getName();
String ticker = fileName.split("\\_")[0];
if (ticker.equals("ASB") || ticker.equals("FRC")) {
if (ticker.equals("ASB")) {
ticker = ticker + "PRD";
}
if (ticker.equals("FRC")) {
ticker = ticker + "PRD";
}
}
Reader reader = new BufferedReader(new FileReader(file));
StringBuilder builder = new StringBuilder();
int c;
while ((c = reader.read()) != -1) {
builder.append((char) c);
}
String string = builder.toString();
ArrayList<String> stringResult = new ArrayList<String>();
if (string != null) {
String[] splitData = string.split("\\s*,\\s*");
for (int i = 0; i <splitData.length; i++) {
if (!(splitData[i] == null) || !(splitData[i].length() ==0)) {
stringResult.add(splitData[i].trim());
}
}
}
for (int i = 0; i < stringResult.size(); i++) {
int cL = stringResult.get(i).length();
for (int x = 0; x < cL; x++) {
if (Character.isLetter(stringResult.get(i).charAt(x))) {
System.out.println("index: " + i);
System.out.println(stringResult.get(i));
break;
}
}
}
Here are some photos of what's happening
https://postimg.org/image/a9qc1qggz/
https://postimg.org/image/mvna7p7s3/
Any idea on how to fix this?
I also noticed there is a space in front of the row names in the spreadsheets, which I suspect may be part of the problem.

The problem is coming from where you are reading in the file, here:
Reader reader = new BufferedReader(new FileReader(file));
StringBuilder builder = new StringBuilder();
int c;
while ((c = reader.read()) != -1) {
builder.append((char) c);
}
String string = builder.toString();
This reads all the characters into a single string, including the new line character(s). When you then split the string, you are not splitting on the new line character(s) and so you end up with what you are seeing.
As mentioned but others I strongly urge you to use one of the many csv parsers that already exist.
The simple (but ugly) fix would be to also split on newlines. A better fix would be to use the readLine() method of the BufferedReader.
Also != is your friend.

As Erwin stated in the comments, your Pattern that you are splitting on just looks for commas with whitespace around them. It looks like you know what format your data will be in since you know that the data will be separated by either whitespace comma whitespace or a newline. Seems to me you just need to change your input to "\\s*,\\s*|$", which is the regex that says that. Like has been mentioned you need to know beforehand that the data doesn't include whitespace comma whitespace in any of the fields or this breaks.

ArrayIndexOutOfBoundsException - when parsing a csv file

I want to transform a csv file. My file looks like that:
I am using the opencsv libary to parse my csv. That is my run method to parse the file:
public void run() throws Exception {
CSVReader reader = new CSVReader(new FileReader(csvFile), ';');
String [] nextLine;
int i = -1;
String fileName = "";
String companyName = "";
String currency = "";
String writerPath;
List<String> returnList = null;
List<String> dateList = null;
while ((nextLine = reader.readNext()) != null && i < 10) {
String[] line = nextLine;
System.out.println(line[0]);
System.out.println(line);
i++;
//fileName of the String
if(!line[0].contains("NULL")) {
fileName = line[0];
}
writerPath = "C:\\Users\\Desktop\\CSVOutput\\" + fileName + ".csv";
//write csv file
CSVWriter writer = new CSVWriter(new FileWriter(writerPath), ';');
//write Header
String[] entries = "Name;Date;TotalReturn;Currency".split(";");
writer.writeNext(entries);
//create Content
//companyName of the String
if(!line[1].contains("Name")) {
companyName = line[1];
System.out.println(companyName);
}
//currency
if(!line[2].contains("CURRENCY")) {
currency = line[2];
}
//total returns
returnList = new ArrayList<String>();
if(line[0].contains("NULL")) {
for(int j = 3; j <= line.length; j++) {
returnList.add(line[j]); // EXCPETION COMES HERE!
}
}
//"Name;Date;TotalReturn;Currency"
List<String[]> data = new ArrayList<String[]>();
for(int m = 0; m <= line.length; m++) {
data.add(new String[] {companyName, "lolo", "hereComesTheDateLater", currency});
}
writer.writeAll(data);
//close Writer
writer.close();
}
System.out.println("Done");
}
}
I am getting an
java.lang.ArrayIndexOutOfBoundsException: 3039
at com.TransformCSV.main.ParseCSV.run(ParseCSV.java:78)
at com.TransformCSV.main.ParseCSV.main(ParseCSV.java:20)
at this line: returnList.add(line[j]);?
Why? What are possible ways to fix that?
I really appreciate your answer!

You want j < line.length and not <=. If there are 10 elements in an Array then there is not an item at index 10 - you only have 0-9.
Further using loads of variables and assigning them is not the preferred way to parse CSV. Java is an Object Orientated language.
Use an Object to represent each line and bind the line using the opencsv javabean API

You are parsing the file till length of file <= instead you have to use <. It will access the file till line.length - 1
Replace with this
for(int j = 3; j <line.length; j++) {
returnList.add(line[j]);
}

Finding a specific line in Java using split()

I have a file with lines of text like this:
[A]
This is one line.
This is another line.
[B]
A third line.
...
and so forth. I want to read this file into Java and look for the lines which only contain [A] etc. for further reference. I tried:
Resources res = getResources();
InputStream in_s = res.openRawResource(R.raw.texts);
byte[] b = new byte[in_s.available()];
in_s.read(b);
String textstring = new String(b);
String[] textarr = textstring.split("[\\r\\n]+");
And then:
int lineB = 0;
for (int i=0; i<textarr.length; i++) {
if textarr[i].substring(0, 3) == "[B]") lineB = i;
}
Afterwards, line is still zero. First I thought this has something to do with how new lines are handled (I'm using Windows), but I also had no luck with substring(0,3). I want this to give me lineB = 3, any ideas what I'm doing wrong?

Use String#startsWith like this:
int lineB = 0;
for (int i=0; i<textarr.length; i++) {
if (textarr[i].startsWith("[B]"))
lineB = i;
}

Try String.contains(CharSequence s) or String.startsWith(String prefix)
edit: Oh, and try BufferedReader:
BufferedReader in = new BufferedReader(new FileReader("foo.in"));
String line = "";
while ((line = in.readLine()) != null)
if(line.startsWith("whatever")) ...

java regular expression getting values from a txt file [duplicate]

I am new to Java. I have one text file with below content.
`trace` -
structure(
list(
"a" = structure(c(0.748701,0.243802,0.227221,0.752231,0.261118,0.263976,1.19737,0.22047,0.222584,0.835411)),
"b" = structure(c(1.4019,0.486955,-0.127144,0.642778,0.379787,-0.105249,1.0063,0.613083,-0.165703,0.695775))
)
)
Now what I want is, I need to get "a" and "b" as two different array list.

You need to read the file line by line. It is done with a BufferedReader like this :
try {
FileInputStream fstream = new FileInputStream("input.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
String strLine;
int lineNumber = 0;
double [] a = null;
double [] b = null;
// Read File Line By Line
while ((strLine = br.readLine()) != null) {
lineNumber++;
if( lineNumber == 4 ){
a = getDoubleArray(strLine);
}else if( lineNumber == 5 ){
b = getDoubleArray(strLine);
}
}
// Close the input stream
in.close();
//print the contents of a
for(int i = 0; i < a.length; i++){
System.out.println("a["+i+"] = "+a[i]);
}
} catch (Exception e) {// Catch exception if any
System.err.println("Error: " + e.getMessage());
}
Assuming your "a" and"b" are on the fourth and fifth line of the file, you need to call a method when these lines are met that will return an array of double :
private static double[] getDoubleArray(String strLine) {
double[] a;
String[] split = strLine.split("[,)]"); //split the line at the ',' and ')' characters
a = new double[split.length-1];
for(int i = 0; i < a.length; i++){
a[i] = Double.parseDouble(split[i+1]); //get the double value of the String
}
return a;
}
Hope this helps. I would still highly recommend reading the Java I/O and String tutorials.

You can play with split. First find the line in the text that matches "a" (or "b"). Then do something like this:
Array[] first= line.split("("); //first[2] will contain the values
Then:
Array[] arrayList = first[2].split(",");
You will have the numbers in arrayList[]. Be carefull with the final brackets )), because they have a "," right after. But that is code depuration and it is your mission. I gave you the idea.