Develop Reference

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]);

Assigning part of txt file to java variable

I have a txt file with the following output:
"CN=COUD111255,OU=Workstations,OU=Mis,OU=Accounts,DC=FLHOSP,DC=NET"
What I'm trying to do is read the COUD111255 part and assign it to a java variable. I assigned ldap to sCurrentLine, but I'm getting a null point exception. Any suggestions.
try (BufferedReader br = new BufferedReader(new FileReader("resultofbatch.txt")))
{
final Pattern PATTERN = Pattern.compile("CN=([^,]+).*");
try {
while ((sCurrentLine = br.readLine()) != null) {
//Write the function you want to do, here.
String[] tokens = PATTERN.split(","); //This will return you a array, containing the string array splitted by what you write inside it.
//should be in your case the split, since they are seperated by ","
}
System.out.println(sCurrentLine);
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
} catch (IOException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}
}
});

You just need to read data from a file line by line and assign the line to your variable str. Refer to following link:
How to read a large text file line by line using Java?

Your code is almost correct. You are writing this string to standard output - what for? If I understand you right, what you need is simply this:
private static final Pattern PATTERN = Pattern.compile("CN=([^,]+).*");
public static String solve(String str) {
Matcher matcher = PATTERN.matcher(str);
if (matcher.matches()) {
return matcher.group(1);
} else {
throw new IllegalArgumentException("Wrong string " + str);
}
}
This call
solve("CN=COUD111255,OU=Workstations,OU=Mis,OU=Accounts,DC=FLHOSP,DC=NET")
gave me "COUD111255" as answer.

To read from .txt, use BufferedReader. To create a one, write:
BufferedReader br = new BufferedReader(new FileReader("testing.txt"));
testing.txt is the name of the txt that you're reading and must be in your java file. After initializing, you must continue as:
while ((CurrentLine = br.readLine()) != null) {
//Write the function you want to do, here.
String[] tokens = CurrentLine.split(","); //This will return you a array, containing the string array splitted by what you write inside it.
//should be in your case the split, since they are seperated by ","
}
You got tokens array which is = [CN=COUD111255,OU=Workstations OU=Mis,OU=Accounts,DC=FLHOSP,DC=NET].
So, now take the 0th element of array and make use of it. You got the CN=COUD111255, now! Leaving here not to give whole code.
Hope that helps !

remove '#' symbol from the beginning of the string in java

Sample data in csv file
##Troubleshooting DHCP Configuration
#Module 3: Point-to-Point Protocol (PPP)
##Configuring HDLC Encapsulation
Hardware is HD64570
So i want to get the lines as
#Troubleshooting DHCP Configuratin
Module 3: Point-to-Point Protocol(PPP)
#Configuring HDLC Encapsulation
Hardware is HD64570
I have written sample code
public class ReadCSV {
public static BufferedReader br = null;
public static void main(String[] args) {
ReadCSV obj = new ReadCSV();
obj.run();
}
public void run() {
String sCurrentLine;
try {
br = new BufferedReader(new FileReader("D:\\compare\\Genre_Subgenre.csv"));
try {
while ((sCurrentLine = br.readLine()) != null) {
if(sCurrentLine.charAt(0) == '#'){
System.out.println(sCurrentLine);
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
I am getting below error
##Troubleshooting DHCP Configuration
#Module 3: Point-to-Point Protocol (PPP)
##Configuring HDLC Encapsulation
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(Unknown Source)
at example.ReadCSV.main(ReadCSV.java:19)
Please suggest me how to do this?

Steps:
Read the CSV file line by line
Use line.replaceFirst("#", "") to remove the first # from each line
Write the modified lines to an output stream (file or String) which suites you

If the variable s contains the content of the CSV file as String
s = s.replace("##", "#");
will replace all the occurrencies of '##" with '#'

You need something like String line=buffer.readLine()
Check the first character of the line with line.charAt(0)=='#'
Get the new String with String newLine=line.substring(1)

This is a rather trivial question. Rather than do the work for you, I'll outline the steps that you need to take without gifting you the answer.
Read in a file line by line
Take the first line and check if the first character of this line is a # - If it is, create a substring of this line excluding the first character ( or use fileLine.replaceFirst("#", ""); )
Store this line somewhere in an array like data structure or simply replace the current variable with the edited one ( fileLine = fileLine.replaceFirst("#", ""); )
Repeat until no more lines left from file.
If you want to add these changes to the file, simply overwrite the old file with the new lines (e.g. Using a steam reader and setting second parameter to false would overwrite)
Make an attempt and show us what you have tried, people will be more likely to help if they believe you have attempted the problem yourself thoroughly first.

package stackoverflow.q_25054783;
import java.util.Arrays;
public class RemoveHash {
public static void main(String[] args) {
String [] strArray = new String [3];
strArray[0] = "##Troubleshooting DHCP Configuration";
strArray[1] = "#Module 3: Point-to-Point Protocol (PPP)";
strArray[2] = "##Configuring HDLC Encapsulation";
System.out.println("Original array: " + Arrays.toString(strArray));
for (int i = 0; i < strArray.length; i++) {
strArray[i] = strArray[i].replaceFirst("#", "");
}
System.out.println("Updated array: " + Arrays.toString(strArray));
}
}
//Output:
//Original array: [##Troubleshooting DHCP Configuration, #Module 3: Point-to-Point Protocol (PPP), ##Configuring HDLC Encapsulation]
//Updated array: [#Troubleshooting DHCP Configuration, Module 3: Point-to-Point Protocol (PPP), #Configuring HDLC Encapsulation]

OpenCSV reads CSV file line by line and gives you an array of strings, where each string is one comma separated value, right? Thus, you are operating on a string.
You want to remove '#' symbol from the beginning of the string (if it is there). Correct?
Then this should do it:
CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
String [] nextLine;
while ((nextLine = reader.readNext()) != null) {
if (nextLine[0].charAt(0) == '#') {
nextLine[0] = nextLine[0].substring(1, nextLine[0].length());
}
}
Replacing the first '#' symbol on each of the lines in the CSV file.

private List<String> getFileContentWithoutFirstChar(File f){
try (BufferedReader input = new BufferedReader(new InputStreamReader(new FileInputStream(f), Charset.forName("UTF-8")))){
List<String> lines = new ArrayList<String>();
for(String line = input.readLine(); line != null; line = input.readLine()) {
lines.add(line.substring(1));
}
return lines
} catch(IOException e) {
e.printStackTrace();
System.exit(1);
return null;
}
}
private void writeFile(List<String> lines, File f){
try(BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(f), StandardCharsets.UTF_8))){
for(String line : lines){
bw.write(content);
}
bw.flush();
}catch (Exception e) {
e.printStackTrace();
}
}
main(){
File f = new File("file/path");
List<Stirng> lines = getFileContent(f);
f.delete();
writeFile(lines, f);
}

Regex extract string, why my pattern don't works?

I have a long string in this format (a long single line in file):
"1":"Aname","2":"AnotherName","3":"Sempronio"
I want to extract the number and the name and save them on a Map.
I tried this:
FileReader fileReader = null;
BufferedReader br = null;
File file = new File("./SingleLineFileNames.txt");
try {
fileReader = new FileReader(file);
br = new BufferedReader(fileReader);
String line;
Pattern p = Pattern.compile("\"(\\d+)\":\"([\\w-.' ]+)\"");
Matcher matcher;
while((line = br.readLine()) != null) {
matcher = p.matcher(line);
String name;
int i = 1;
while((name = matcher.group(i)) != null){
// save in map
i++;
}
}
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
finally {
try {
br.close();
fileReader.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
return null;
result is java.lang.IllegalStateException: No match found
It's the right way to iterate on groups?
Where I wrong?

First split the String at , (String#split) and then split each resulting array element at : to get key and value. With input strings like these, I wonder what kind of masochism is on the developers using regex sledgehammers breaking these simple nuts..

If you use hyphen inside [] then always place at the first or at the last.
Pattern p = Pattern.compile("\"(\\d+)\":\"([-\\w.' ]+)\"");
^ here
Also the way you are checking the group() is not correct. Check here:
while(matcher.find()){
System.out.println(matcher.group(1));
System.out.println(matcher.group(2));
}

Remove the broken square bracket construct ([\\w-.' ]+) . For the name containing word characters only, it is enough to put (\\w+) there.

Read next word in java

I have a text file that has following content:
ac und
accipio annehmen
ad zu
adeo hinzugehen
...
I read the text file and iterate through the lines:
Scanner sc = new Scanner(new File("translate.txt"));
while(sc.hasNext()){
String line = sc.nextLine();
}
Each line has two words. Is there any method in java to get the next word or do I have to split the line string to get the words?

You do not necessarily have to split the line because java.util.Scanner's default delimiter is whitespace.
You can just create a new Scanner object within your while statement.
Scanner sc2 = null;
try {
sc2 = new Scanner(new File("translate.txt"));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
while (sc2.hasNextLine()) {
Scanner s2 = new Scanner(sc2.nextLine());
while (s2.hasNext()) {
String s = s2.next();
System.out.println(s);
}
}

You already get the next line in this line of your code:
String line = sc.nextLine();
To get the words of a line, I would recommend to use:
String[] words = line.split(" ");

Using Scanners, you will end up spawning a lot of objects for every line. You will generate a decent amount of garbage for the GC with large files. Also, it is nearly three times slower than using split().
On the other hand, If you split by space (line.split(" ")), the code will fail if you try to read a file with a different whitespace delimiter. If split() expects you to write a regular expression, and it does matching anyway, use split("\\s") instead, that matches a "bit" more whitespace than just a space character.
P.S.: Sorry, I don't have right to comment on already given answers.

you're better off reading a line and then doing a split.
File file = new File("path/to/file");
String words[]; // I miss C
String line;
HashMap<String, String> hm = new HashMap<>();
try (BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file), "UTF-8")))
{
while((line = br.readLine() != null)){
words = line.split("\\s");
if (hm.containsKey(words[0])){
System.out.println("Found duplicate ... handle logic");
}
hm.put(words[0],words[1]); //if index==0 is ur key
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

You can just use Scanner to read word by word, Scanner.next() reads the next word
try {
Scanner s = new Scanner(new File(filename));
while (s.hasNext()) {
System.out.println("word:" + s.next());
}
} catch (IOException e) {
System.out.println("Error accessing input file!");
}