Develop Reference

Java: Read file as long as a new date is found

I want to read the file and add each entry to an arraylist on a date. But the date should also be included.
File Example:
15.09.2002 Hello, this is the first entry.
\t this line, I also need in the first entry.
\t this line, I also need in the first entry.
\t this line, I also need in the first entry.
17.10.2020 And this ist the next entry
I tried this. But the Reader reads only the first Line
public class versuch1 {
public static void main(String[] args) {
ArrayList<String> liste = new ArrayList<String>();
String lastLine = "";
String str_all = "";
String currLine = "";
try {
FileReader fstream = new FileReader("test.txt");
BufferedReader br = new BufferedReader(fstream);
while ((currLine = br.readLine()) != null) {
Pattern p = Pattern
.compile("[0-3]?[0-9].[0-3]?[0-9].(?:[0-9]{2})?[0-9]{2} [0-2]?[0-9]:[0-6]?[0-9]:[0-5]");
Matcher m = p.matcher(currLine);
if (m.find() == true) {
lastLine = currLine;
liste.add(lastLine);
} else if (m.find() == false) {
str_all = currLine + " " + lastLine;
liste.set((liste.indexOf(currLine)), str_all);
}
}
br.close();
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
System.out.print(liste.get(0) + " "+liste.get(1);
}
}

I have solved my problem :)
public class versuch1 {
public static void main(String[] args) {
ArrayList<String> liste = new ArrayList<String>();
String lastLine = "";
String currLine = "";
String str_all = "";
try {
FileReader fstream = new FileReader("test.txt");
BufferedReader br = new BufferedReader(fstream);
currLine = br.readLine();
while (currLine != null) {
Pattern p = Pattern
.compile("[0-3]?[0-9].[0-3]?[0-9].(?:[0-9]{2})?[0-9]{2} [0-2]?[0-9]:[0-6]?[0-9]:[0-5]");
Matcher m = p.matcher(currLine);
if (m.find() == true) {
liste.add(currLine);
lastLine = currLine;
} else if (m.find() == false) {
liste.set((liste.size() - 1), (str_all));
lastLine = str_all;
}
currLine = br.readLine();
str_all = lastLine + currLine;
}
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
System.out.print(liste.get(1) + " ");
}
}

While reading the lines, keep a "current entry".
If the line read begins with a date, then it belongs to a new entry. In this case add the current entry to the list of entries and create a new current entry consisting of the read line.
If the line did not begin with a date, just add it to the current entry.
For this to work, you need to read the first line into the current entry before the loop. And after the loop you need to add the current entry to the list of entries. This in turn only works if there is at least one line and the first line begins with a date. So handle the special case of no lines specially (use if-else). And report an error if the first line does not begin with a date.
Happy coding.

Search for multiline String in a text file

I have a text file from which i am trying to search for a String which has multiple lines. A single string i am able to search but i need multi line string to be searched.
I have tried to search for single line which is working fine.
public static void main(String[] args) throws IOException
{
File f1=new File("D:\\Test\\test.txt");
String[] words=null;
FileReader fr = new FileReader(f1);
BufferedReader br = new BufferedReader(fr);
String s;
String input="line one";
// here i want to search for multilines as single string like
// String input ="line one"+
// "line two";
int count=0;
while((s=br.readLine())!=null)
{
words=s.split("\n");
for (String word : words)
{
if (word.equals(input))
{
count++;
}
}
}
if(count!=0)
{
System.out.println("The given String "+input+ " is present for "+count+ " times ");
}
else
{
System.out.println("The given word is not present in the file");
}
fr.close();
}
And below are the file contents.
line one
line two
line three
line four

Use the StringBuilder for that, read every line from file and append them to StringBuilder with lineSeparator
StringBuilder lineInFile = new StringBuilder();
while((s=br.readLine()) != null){
lineInFile.append(s).append(System.lineSeparator());
}
Now check the searchString in lineInFile by using contains
StringBuilder searchString = new StringBuilder();
builder1.append("line one");
builder1.append(System.lineSeparator());
builder1.append("line two");
System.out.println(lineInFile.toString().contains(searchString));

More complicated solution from default C (code is based on code from book «The C programming language» )
final String searchFor = "Ich reiß der Puppe den Kopf ab\n" +
"Ja, ich reiß' ich der Puppe den Kopf ab";
int found = 0;
try {
String fileContent = new String(Files.readAllBytes(
new File("puppe-text").toPath()
));
int i, j, k;
for (i = 0; i < fileContent.length(); i++) {
for (k = i, j = 0; (fileContent.charAt(k++) == searchFor.charAt(j++)) && (j < searchFor.length());) {
// nothig
}
if (j == searchFor.length()) {
++found;
}
}
} catch (IOException ignore) {}
System.out.println(found);

Why don't you just normalize all the lines in the file to one string variable and then just count the number of occurrences of the input in the file. I have used Regex to count the occurrences but can be done in any custom way you find suitable.
public static void main(String[] args) throws IOException
{
File f1=new File("test.txt");
String[] words=null;
FileReader fr = new FileReader(f1);
BufferedReader br = new BufferedReader(fr);
String s;
String input="line one line two";
// here i want to search for multilines as single string like
// String input ="line one"+
// "line two";
int count=0;
String fileStr = "";
while((s=br.readLine())!=null)
{
// Normalizing the whole file to be stored in one single variable
fileStr += s + " ";
}
// Now count the occurences
Pattern p = Pattern.compile(input);
Matcher m = p.matcher(fileStr);
while (m.find()) {
count++;
}
System.out.println(count);
fr.close();
}
Use StringBuilder class for efficient string concatenation.

Try with Scanner.findWithinHorizon()
String pathToFile = "/home/user/lines.txt";
String s1 = "line two";
String s2 = "line three";
String pattern = String.join(System.lineSeparator(), s1, s2);
int count = 0;
try (Scanner scanner = new Scanner(new FileInputStream(pathToFile))) {
while (scanner.hasNext()) {
String withinHorizon = scanner.findWithinHorizon(pattern, pattern.length());
if (withinHorizon != null) {
count++;
} else {
scanner.nextLine();
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
System.out.println(count);

Try This,
public static void main(String[] args) throws IOException {
File f1 = new File("./src/test/test.txt");
FileReader fr = new FileReader(f1);
BufferedReader br = new BufferedReader(fr);
String input = "line one";
int count = 0;
String line;
while ((line = br.readLine()) != null) {
if (line.contains(input)) {
count++;
}
}
if (count != 0) {
System.out.println("The given String " + input + " is present for " + count + " times ");
} else {
System.out.println("The given word is not present in the file");
}
fr.close();
}

Java - Reading a line from a file containing text and number

I'm just trying to do an exercise where I have to read a particular file called test.txt in the following format:
Sampletest 4
What I want to do is that I want to store the text part in one variable and the number in another. I am still a beginner so I had to google quite a bit to find something that would at-least work, here what I got so far.
public static void main(String[] args) throws Exception{
try {
FileReader fr = new FileReader("test.txt");
BufferedReader br = new BufferedReader(fr);
String str;
while((str = br.readLine()) != null) {
System.out.println(str);
}
br.close();
} catch(IOException e) {
System.out.println("File not found");
}

Use a Scanner, which makes reading your file way easier than DIY code:
try (Scanner scanner = new Scanner(new FileInputStream("test.txt"));) {
while(scanner.hasNextLine()) {
String name = scanner.next();
int number = scanner.nextInt();
scanner.nextLine(); // clears newlines from the buffer
System.out.println(str + " and " + number);
}
} catch(IOException e) {
System.out.println("File not found");
}
Note the use of the try-with-resources syntax, which closes the scanner automatically when the try is exited, usable because Scanner implements Closeable.

You just need:
String[] parts = str.split(" ");
And parts[0] is the text (sampletest)
And parts[1] is the number 4

It seems like you are reading the whole file content (from test.txt file) line by line, so you need two separate List objects to store the numeric and non-numeric lines as shown below:
String str;
List<Integer> numericValues = new ArrayList<>();//stores numeric lines
List<String> nonNumericValues = new ArrayList<>();//stores non-numeric lines
while((str = br.readLine()) != null) {
if(str.matches("\\d+")) {//check line is numeric
numericValues.add(str);//store to numericList
} else {
nonNumericValues.add(str);//store to nonNumericValues List
}
}

If you are sure the format is always for each line in the file.
String str;
List<Integer> intvalues = new ArrayList<Integer>();
List<String> charvalues = new ArrayList<String>();
try{
BufferedReader br = new BufferedReader(new FileReader("test.txt"));
while((str = br.readLine()) != null) {
String[] parts = str.split(" ");
charvalues.add(parts[0]);
intvalues.add(new Integer(parts[0]));
}
}catch(IOException ioer) {
ioer.printStackTrace();
}

You can use java utilities Files#lines()
Then you can do something like this. Use String#split() to parse each line with a regular expression, in this example i use a comma.
public static void main(String[] args) throws IOException {
try (Stream<String> lines = Files.lines(Paths.get("yourPath"))) {
lines.map(Representation::new).forEach(System.out::println);
}
}
static class Representation{
final String stringPart;
final Integer intPart;
Representation(String line){
String[] splitted = line.split(",");
this.stringPart = splitted[0];
this.intPart = Integer.parseInt(splitted[1]);
}
}

Omit elements in array based on the first word

What I'm looking to do here is process a log file, in my case it's squid's access.log. I want to have my program take a look at the first 'word' in the file, which is the time in Unix format of when the URL was accessed. In other parts of the program, I designed a time class, which gets the time the program was last run in Unix time, and I want to compare this time to the first word in the file, which happens to be a Unix time.
My initial thinking on how to do this is that I process the file, store it in array, then based on the first word in the file, omit the lines by removing it from the array that the processed file is in, and put it in another array
Here's what I've got so far. I'm pretty sure that I'm close, but this is the first time that I've done file processing, so I don't exactly know what I'm doing here.
private void readFile(File file) throws FileNotFoundException, IOException{
String[] lines = new String[getLineCount(file)];
Long unixTime = time.getUnixLastRun();
String[] removedTime = new String[getLineCount(file)];
try(BufferedReader br = new BufferedReader(new FileReader(file))) {
int i = 0;
for(String line; (line = br.readLine()) != null; i++) {
lines[i] = line;
}
}
for(String arr: lines){
System.out.println(arr);
}
}

private void readFile(File file) {
List<String> lines = new ArrayList<String>();
List<String> firstWord = new ArrayList<String>();
try (BufferedReader br = new BufferedReader(new FileReader(file))) {
String sCurrentLine;
while ((sCurrentLine = br.readLine()) != null) {
// Adds the entire first line
lines.add(sCurrentLine);
// Adds the first word
firstWord.add(sCurrentLine.split(" ")[0]);
}
} catch (IOException e) {
e.printStackTrace();
}
}
If you want you can use your arrays.

private void readFile(File file) throws FileNotFoundException, IOException {
String[] lines = new String[getLineCount(file)];
Long unixTime = time.getUnixLastRun();
String[] removedTime = new String[getLineCount(file)];
try (BufferedReader br = new BufferedReader(new FileReader(file))) {
int i = 0;
for (String line; (line = br.readLine()) != null; i++) {
lines[i] = line;
}
}
ArrayList<String> logsToBeUsed = new ArrayList<String>();
for (String arr : lines) {
//Gets the first word from the line and compares it with the current unix time, if it is >= unix time
//then we add it to the list of Strings to be used
try{
if(Long.parseLong(getFirstWord(arr)) >= unixTime){
logsToBeUsed.add(arr);
}
}catch(NumberFormatException nfe){
//Means the first word was not a float, do something here
}
}
}
private String getFirstWord(String text) {
if (text.indexOf(' ') > -1) {
return text.substring(0, text.indexOf(' '));
} else {
return text;
}
}
This is the answer according to the code you posted. This can be done more efficiently as you can use an ArrayList to store the lines from the file rather than first reading the line number getLineCount(file) as you open the file twice. And in the for loop you are declaring the String object again and again.

skip inserting first line of csv file

I have a method that takes data from a .csv file and puts it into an array backwards
(first row goes in last array slot) however I would like the first row in the .csv file to not be in the array. How would I accomplish this? Here is my code thus far:
public static String[][] parse(String symbol) throws Exception{
String destination = "C:/"+symbol+"_table.csv";
LineNumberReader lnr = new LineNumberReader(new FileReader(new File(destination)));
lnr.skip(Long.MAX_VALUE);
String[][] stock_array = new String[lnr.getLineNumber()][3];
try{
BufferedReader br = new BufferedReader(new FileReader(destination));
String strLine = "";
StringTokenizer st = null;
int line = lnr.getLineNumber()-1;
while((strLine = br.readLine()) != null){
st = new StringTokenizer(strLine, ",");
while(st.hasMoreTokens()){
stock_array[line][0] = st.nextToken();
st.nextToken();
stock_array[line][1] = st.nextToken();
stock_array[line][2] = st.nextToken();
st.nextToken();
st.nextToken();
st.nextToken();
}
line--;
}
}
catch(Exception e){
System.out.println("Error while reading csv file: " + e);
}
return stock_array;
}

You can skip the first line by just reading it in and doing nothing. Do this just before your while loop:
br.readLine();
To make sure that your array is the right size and lines get stored in the right places, you should also make these changes:
String[][] stock_array = new String[lnr.getLineNumber()-1][3];
...
int line = lnr.getLineNumber()-2;

Your code is not efficient, as far as my knowledge goes. Also, you are using linenumberreader.skip(long.max_value), which is not a correct/confirmed way to find the line count of the file. StringTokenizer is kind of deprecated way of splitting tokens. I would code it, in the following way:
public static List<String[]> parse(String symbol) throws Exception {
String destination = "C:/"+symbol+"_table.csv";
List<String[]> lines = new ArrayList<String[]>();
try{
BufferedReader br = new BufferedReader(new FileReader(destination));
int index = 0;
while((line = br.readLine()) != null){
if(index == 0) {
index++;
continue; //skip first line
}
lines.add(line.split(","));
}
if(lines != null && !lines.isEmpty()) {
Collections.reverse(lines);
}
} catch(IOException ioe){
//IOException Handling
} catch(Exception e){
//Exception Handling
}
return lines;
}