Develop Reference

How do I split multiple lines with multiple delimeters?

I have a .txt file with multiple lines with many emails such as Mike#sport.member.com, Laura#music.member.com, Quinn#music.member.com. How do I split them so I can add them to seperate arraylists like music or sport?
Mike: sport
Laura: music
Quinn: music
Thanks so much.

you can use regex
Pattern pattern = Pattern.compile("(\\w+)#(\\w+).(\\w+).(\\w+)");
Matcher matcher = pattern.matcher("Laura#music.member.com");
if (matcher.find()) {
matcher.group(1); //this return the name
matcher.group(2); //this return music sport
matcher.group(3); // get the company name
matcher.group(4); // get the domain com in this case
}
use this to fill the arraylist as you like
and have a nice day :)

If you don't mind using ArrayUtils you can use this code:
String[] emails = new String[] {"Mike#sport.member.com", "Laura#music.member.com", "Quinn#music.member.com"};
int startLength;
String[][] split = new String[emails.length][];
for(int i = 0; i < emails.length; i++) {
split[i] = emails[i].split("#"); //split by #
startLength = split[i].length;
for(int j = 0; j < startLength; j++) {
split[i] = ArrayUtils.addAll(split[i], split[i][0].split("\\.")); //Split by . and add items to the end of the array
split[i] = ArrayUtils.remove(split[i], 0); //remove the first item of the array
}
}
System.out.println(Arrays.deepToString(split));
Output:
[[Mike, sport, member, com], [Laura, music, member, com], [Quinn, music, member, com]]
What this does is it uses .split("#") to split the emails into arrays separated by "#" Then goes through for array and splits each item in the array with .split(".").
As it splits the elements the second time it adds them to the end of the split array and removes the first item (which was the item that it just split up).
Note that I had to make the startLength variable to keep track of the original size of the split array because in the second loop its constantly changing length.
This gives you a 2D array with all the items but I won't blame you for no using this because its a bit of a mess.

There are two steps to solve this problem.
Read lines from file(a.txt).
public List<String> readFile() throws IOException {
String fileName = "/Users/folder/a.txt";
FileInputStream inputStream = new FileInputStream(fileName);
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
String str = null;
List<String> list = new ArrayList<>();
while ((str = bufferedReader.readLine()) != null) {
list.add(str);
}
//close
inputStream.close();
bufferedReader.close();
return list;
}
Split line, take out data.
List<String> lines = readFile();
Pattern pattern = Pattern.compile("([a-zA-Z]+)#([a-zA-Z]+)");
for (String line : lines) {
Matcher matcher = pattern.matcher(line);
if (matcher.find()){
System.out.println(matcher.group(1) + ":" + matcher.group(2));
}
}
The result is
Mike:sport
Laura:music
Quinn:music

How do I count the occurence of a word in an array in Java?

I am working on a project where I have to read the data from a file into my code, in the txt file I have columns of data, and I have managed to separate each column of data into an array with this code.
public static void main(String[] args) {
String line = "";
String date = "";
ArrayList<String> date = new ArrayList<String>();
try {
FileReader fr = new FileReader("list.txt");
BufferedReader br = new BufferedReader(fr);
while ((line = br.readLine()) != null) {
line.split("\\s+");
date.add(line.split("\\s+")[0]);
System.out.println(line.split("\\s+")[0]);
}
} catch (IOException e) {
System.out.println("File not found!");
}
This will output the first column of data from the "list.txt" file which is...
30-Nov-2016
06-Oct-2016
05-Feb-2016
04-Sep-2016
18-Apr-2016
09-Feb-2016
22-Oct-2016
20-Aug-2016
17-Dec-2016
25-Dec-2016
However, I want to count the occurrence of the word "Feb" so for example it will come up...
"The month February occurs: 2 times"
But I'm struggling to find the right code, could somebody please help me on this matter I've been trying for over 24 hours, any help will be greatly appreciated, I can't find any other questions that help me.

Another solution could be using split
String month = "Feb";
int count = 0;
while ((line = br.readLine()) != null)
{
String strDate = line.split("\\s+")[0]; // get first column, which has date
String temp = strDate.split("\\-")[1]; // get Month from extracted date.
if (month.equalsIgnoreCase(temp))
{
count++;
// or store strDate into List for further process.
}
}
System.out.println (count);// should print total occurrence of date with Feb month
==Edited==
Since, you are extracting date from each line using line.split("\\s+")[0], which means actual string, which only contains date would be extract string.

For simplicity, you could simply use a regular expression, something like...
Pattern p = Pattern.compile("Feb", Pattern.CASE_INSENSITIVE);
Matcher m = p.matcher("30-Nov-2016, 06-Oct-2016, 05-Feb-2016, 04-Sep-2016, 18-Apr-2016, 09-Feb-2016, 22-Oct-2016, 20-Aug-2016, 17-Dec-2016, 25-Dec-2016");
int count = 0;
while (m.find()) {
count++;
}
System.out.println("Count = " + count);
Which, based on the input, would be 2.
Now, obviously, if you're reading each value from a file one at a time, this is not that efficient, and simply using something like...
if (line.toLowerCase().concat("feb")) {
count++;
}
would be simple and quicker
Updated...
So, based on the provided input data and the following code...
Pattern p = Pattern.compile("Feb", Pattern.CASE_INSENSITIVE);
int count = 0;
try (BufferedReader br = new BufferedReader(new InputStreamReader(Test.class.getResourceAsStream("Data.txt")))) {
String text = null;
while ((text = br.readLine()) != null) {
Matcher m = p.matcher(text);
if (m.find()) {
count++;
}
}
System.out.println(count);
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
It prints 67.
Now, this is brute force method, because I'm checking the whole line. In order to overcome possible mismatches in the text, you should split the line by the common delimiter (ie tab character) and check the first element, for example...
String[] parts = text.split("\t");
Matcher m = p.matcher(parts[0]);

How can I read a specifc column from a text file and calculate the average of this column?

I am a little stuck with a java exercise I am currently working on. I have a text file in this format:
Quio Kla,2221,3.6
Wow Pow,3332,9.3
Zou Tou,5556,9.7
Flo Po,8766,8.1
Andy Candy,3339,6.8
I now want to calculate the average of the whole third column, but I have to extract the data first I believe and store it in an array. I was able to read all the data with a buffered reader and print out the entire file in console, but that did not get me closer to get it into an array. Any suggestions on how I can read in a specific column of a text file with a buffered readder into an array would be highly appreciated.
Thank you very much in advance.

You can split your text file by using this portion of code:
BufferedReader in = null;
try {
in = new BufferedReader(new FileReader("textfile.txt"));
String read = null;
while ((read = in.readLine()) != null) {
String[] splited = read.split(",");
for (String part : splited) {
System.out.println(part);
}
}
} catch (IOException e) {
System.out.println("There was a problem: " + e);
e.printStackTrace();
} finally {
try {
in.close();
} catch (Exception e) {
}
}
And then you'll have all your columns in the array part.

It`s definitely not the best solution, but should be sufficient for you
BufferedReader input = new BufferedReader(new FileReader("/file"));
int numOfColumn = 2;
String line = "";
ArrayList<Integer>lines = new ArrayList<>();
while ((line = input.readLine()) != null) {
lines.add(Integer.valueOf(line.split(",")[numOfColumn-1]));
}
long sum =0L;
for(int j:lines){
sum+=j;
}
int avg = (int)sum/lines.size();

I'm going to assume each data set is separated by newline characters in your text file.
ArrayList<Double> thirdColumn = new ArrayList<>();
BufferedReader in = null;
String line=null;
//initialize your reader here
while ((line = in.readLine())!=null){
String[] split = line.split(",");
if (split.length>2)
thirdColumn.add(Double.parseDouble(split[2]));
}
By the end of the while loop, you should have the thirdColumn ArrayList ready and populated with the required data.
The assumption is made that your data set has the following standard format.
String,Integer,Double
So naturally a split by a comma should give a String array of length 3, Where the String at index 2 contains your third column data.

How to split a file into several tokens

I was trying to tokenize an input file from sentences into tokens(words).
For example,
"This is a test file." into five words "this" "is" "a" "test" "file", omitting the punctuations and the white spaces. And store them into an arraylist.
I tried to write some codes like this:
public static ArrayList<String> tokenizeFile(File in) throws IOException {
String strLine;
String[] tokens;
//create a new ArrayList to store tokens
ArrayList<String> tokenList = new ArrayList<String>();
if (null == in) {
return tokenList;
} else {
FileInputStream fStream = new FileInputStream(in);
DataInputStream dataIn = new DataInputStream(fStream);
BufferedReader br = new BufferedReader(new InputStreamReader(dataIn));
while (null != (strLine = br.readLine())) {
if (strLine.trim().length() != 0) {
//make sure strings are independent of capitalization and then tokenize them
strLine = strLine.toLowerCase();
//create regular expression pattern to split
//first letter to be alphabetic and the remaining characters to be alphanumeric or '
String pattern = "^[A-Za-z][A-Za-z0-9'-]*$";
tokens = strLine.split(pattern);
int tokenLen = tokens.length;
for (int i = 1; i <= tokenLen; i++) {
tokenList.add(tokens[i - 1]);
}
}
}
br.close();
dataIn.close();
}
return tokenList;
}
This code works fine except I found out that instead of make a whole file into several words(tokens), it made a whole line into a token. "area area" becomes a token, instead of "area" appeared twice. I don't see the error in my codes. I believe maybe it's something wrong with my trim().
Any valuable advices is appreciated. Thank you so much.
Maybe I should use scanner instead?? I'm confused.

I think Scanner is more approprate for this task. As to this code, you should fix regex, try "\\s+";

Try pattern as String pattern = "[^\\w]"; in the same code

converting one line string into individual integers

if i have this line in a file: 2 18 4 3
and i want to read it as individual integers, how could i?
i'm using bufferreader:
BufferedReader(new FileReader("mp1.data.txt"));
i have tried to use:
BufferedReader(new RandomAccessFile("mp1.data.txt"));
so i can use the method
.readCahr();
but i got an error
if i use
int w = in.read();
it will read the ASCII, and i want it as it is(in dec.)
i was thinking to read it as a string first, but then could i separate each number?
also i was thinking to let each number in a line, but the file i have is long with numbers

Consider using a Scanner:
Scanner scan = new Scanner(new File("mp1.data.txt"));
You can then use scan.nextInt() (which returns an int, not a String) so long as scan.hasNextInt().
No need for that ugly splitting and parsing :)
However, note that this approach will continue reading integers past the first line (if that's not what you want, you should probably follow the suggestions outlined in the other answers for reading and handling only a single line).
Furthermore, hasNextInt() will return false as soon as a non-integer is encountered in the file. If you require a way to detect and handle invalid data, you should again consider the other answers.

It's important to approach larger problems in software engineering by breaking them into smaller ones. In this case, you've got three tasks:
Read a line from the file
Break it into individual parts (still strings)
Convert each part into an integer
Java makes each of these simple:
Use BufferedReader.readLine() to read the line as a string first
It looks like the splitting is as simple as splitting by a space with String.split():
String[] bits = line.split(" ");
If that's not good enough, you can use a more complicated regular expression in the split call.
Parse each part using Integer.parseInt().
Another option for the splitting part is to use the Splitter class from Guava. Personally I prefer that, but it's a matter of taste.

You can split() the String and then use the Integer.parseInt() method in order to convert all the elements to Integer objects.
try {
BufferedReader br = new BufferedReader(new FileReader("mp1.data.txt"));
String line = null;
while ((line = br.readLine()) != null) {
String[] split = line.split("\\s");
for (String element : split) {
Integer parsedInteger = Integer.parseInt(element);
System.out.println(parsedInteger);
}
}
}
catch (IOException e) {
System.err.println("Error: " + e);
}

Once you read the line using BufferedReader, you can use String.split(regex) method to split the string by space ("\\s").
for(String s : "2 18 4 3".split("\\s")) {
int i = Integer.parseInt(s);
System.out.println(i);
}

If you use Java 7+, you can use this utility method:
List<String> lines = Files.readAllLines(file, Charset.forName("UTF-8"));
for (String line: lines) {
String[] numbers = line.split("\\s+");
int firstNumber = Integer.parseInt(numbers[0]);
//etc
}

Try this;
try{
// Open the file that is the first
FileInputStream fstream = new FileInputStream("textfile.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
String strLine;
//Read File Line By Line
while ((strLine = br.readLine()) != null) {
//split line by whitespace
String[] ints = strLine.split(" ");
int[] integers = new int[ints.length];
// to convert from string to integers - Integer.parseInt ("123")
for ( int i = 0; i < ints.length; i++) {
integers[i] = Integer.parseInt(ints[i]);
}
// now do what you want with your integer
// ...
}
in.close();
} catch (Exception e) {//Catch exception if any
System.err.println("Error: " + e.getMessage());
}