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how to copy only a part of .CSV based on first column elements with java

copy part like this(from date to date) I am trying to copy only a part of .CSV file based on the first column (Start Date and Time) data looks like (2019-01-28 10:22:00 AM) but the user have to put it like this (2019/01/28 10:22:00)
this is for windows, java opencsv , this is what I found but dont do what I need exaclty :
like this:
int startLine = get value1 from column csv ;
int endLine = get value2 from column csv;
public static void showLines(String fileName, int startLine, int endLine) throws IOException {
String line = null;
int currentLineNo = 1;
// int startLine = 20056;//40930;
// int currentLineNo = 0;
File currentDirectory = new File(new File(".").getAbsolutePath());
String fromPath = currentDirectory.getCanonicalPath() + "\\Target\\part.csv";
PrintWriter pw = null;
pw = new PrintWriter(new FileOutputStream(fromPath), true);
//pw.close();
BufferedReader in = null;
try {
in = new BufferedReader (new FileReader(fileName));
//read to startLine
while(currentLineNo<startLine) {
if (in.readLine()==null) {
// oops, early end of file
throw new IOException("File too small");
}
currentLineNo++;
}
//read until endLine
while(currentLineNo<=endLine) {
line = in.readLine();
if (line==null) {
// here, we'll forgive a short file
// note finally still cleans up
return;
}
System.out.println(line);
currentLineNo++;
pw.println(line);
}
} catch (IOException ex) {
System.out.println("Problem reading file.\n" + ex.getMessage());
}finally {
try { if (in!=null) in.close();
pw.close();
} catch(IOException ignore) {}
}
}
public static void main(String[] args) throws FileNotFoundException {
int startLine = 17 ;
int endLine = 2222;
File currentDirectory = new File(new File(".").getAbsolutePath());
try {
showLines(currentDirectory.getCanonicalPath() + "\\Sources\\concat.csv", startLine, endLine);
} catch (IOException e) {
e.printStackTrace();
}
// pw.println();
}

Common CSV format uses a comma as a delimiter, with quotations used to escape any column entry that uses them within the data. Assuming that your column one data is consistent with the format you posted, and that I wouldn't have to bother with quotations marks therefor, you could read the columns as:
public static void main(String[] args) {
//This is the path to the file you are writing to
String targetPath = "";
//This is the path to the file you are reading from
String inputFilePath = "";
String line = null;
ArrayList<String> lines = new ArrayList<String>();
boolean add = false;
String startLine = "2019/01/28 10:22:00";
String endLine = "2019/01/28 10:30:00";
String addFlagSplit[] = startLine.replace("/", "-").split(" ");
String addFlag = addFlagSplit[0] + " " + addFlagSplit[1];
String endFlagSplit[] = endLine.replace("/", "-").split(" ");
String endFlag = endFlagSplit[0] + " " + endFlagSplit[1];
try(PrintWriter pw = new PrintWriter(new FileOutputStream(targetPath), true)){
try (BufferedReader input = new BufferedReader(new FileReader(inputFilePath))){
while((line = input.readLine()) != null) {
String date = line.split(",")[0];
if(date.contains(addFlag)) {
add = true;
}else if(date.contains(endFlag)) {
break;
}
if(add) {
lines.add(line);
}
}
}
for(String currentLine : lines) {
pw.append(currentLine + "\n");
}
}catch(FileNotFoundException e) {
e.printStackTrace();
}catch(IOException e) {
e.printStackTrace();
}catch(Exception e) {
e.printStackTrace();
}
}

public static void main(String[] args) throws IOException {
File currentDirectory = new File(new File(".").getAbsolutePath());
String targetPath = currentDirectory.getCanonicalPath() + "\\Target\\part.csv";
String inputFilePath = currentDirectory.getCanonicalPath() + "\\Sources\\concat.csv";
String line = null;
ArrayList<String> lines = new ArrayList<String>();
boolean add = false;
String startLine = "2019/01/28 10:22:00";
String endLine = "2019/04/06 10:30:00";
try(PrintWriter pw = new PrintWriter(new FileOutputStream(targetPath), true)){
try (BufferedReader input = new BufferedReader(new FileReader(inputFilePath))){
while((line = input.readLine()) != null) {
String date = line.split(",")[0];
if(date.contains(startLine)) {
add = true;
}else if(date.contains(endLine)) {
break;
}
if(add) {
lines.add(line);
}
}
}
for(String currentLine : lines) {
pw.append(currentLine + "\n");
}
}catch(FileNotFoundException e) {
e.printStackTrace();
}catch(IOException e) {
e.printStackTrace();
}catch(Exception e) {
e.printStackTrace();
}
}

I want to read a text file and split it based on column value

public class FileSplitter2 {
public static void main(String[] args) throws IOException {
String filepath = "D:\\temp\\test.txt";
BufferedReader reader = new BufferedReader(new FileReader(filepath));
String strLine;
boolean isFirst = true;
String strGroupByColumnName = "city";
int positionOgHeader = 0;
FileWriter objFileWriter;
Map<String, FileWriter> groupByMap = new HashMap<String, FileWriter>();
while ((strLine = reader.readLine()) != null) {
String[] splitted = strLine.split(",");
if (isFirst) {
isFirst = false;
for (int i = 0; i < splitted.length; i++) {
if (splitted[i].equalsIgnoreCase(strGroupByColumnName)) {
positionOgHeader = i;
break;
}
}
}
String strKey = splitted[positionOgHeader];
if (!groupByMap.containsKey(strKey)) {
groupByMap.put(strKey, new FileWriter("D:/TestExample/" + strKey + ".txt"));
}
FileWriter fileWriter = groupByMap.get(strKey);
fileWriter.write(strLine);
}
for (Map.Entry<String,FileWriter> entry : groupByMap.entrySet()) {
entry.getKey();
}
}
}
This is my code. I am not getting a proper result. The file contains 10 columns, and the 5th column is 'city'. There are 10 different cities in a file. I need to split each city a separate file.

You are not calling close on all the FileWriter and hence the data may not get flushed to the file.
See FileWriter is not writing in to a file
At the end of the processing,
groupByMap.values().forEach(fileWriter -> {
try {
fileWriter.close();
} catch (IOException e) {
e.printStackTrace(); //Add appropriate error handling
}
});
There is a bug in your code. You need to move the statements after the if (isFirst) block into the else block. Else, it will create a city.txt file too.

How to create item objects from reading a text file?

I'm trying to read data from a text file and create Item Objects with it.
Item Objects have fields String title, String formatt, boolean onLoan, String loanedTo and String dateLoaned. In my save()method, I print every object to a text file in a new line and the fields are seperated by "$" (dollar sign). How can I read the text file line by line and create a new object from each line and add it to an array.
TextFile Example:
StarWars$DVD$false$null$null
Aliens$Bluray$true$John$Monday
public void save() {
String[] array2 = listForSave();
PrintWriter printer = null;
try {
printer = new PrintWriter(file);
for (String o : array2) {
printer.println(o);
}
printer.close();
} catch ( IOException e ) {
e.printStackTrace();
}
}
public void open(){
try{
FileReader fileReader = new FileReader(file);
BufferedReader bufferedReader = new BufferedReader(fileReader);
StringBuffer stringBuffer = new StringBuffer();
String line;
while ((line = bufferedReader.readLine()) != null) {
stringBuffer.append(line);
stringBuffer.append("\n");
}
fileReader.close();
System.out.println("Contents of file:");
System.out.println(stringBuffer.toString());
}catch ( IOException e ) {
e.printStackTrace();
}
}
Thanks everyone. Here's my final code:
public void open(){
try{
FileReader fileReader = new FileReader(file);
BufferedReader bufferedReader = new BufferedReader(fileReader);
String line;
String[] strings;
while ((line = bufferedReader.readLine()) != null) {
strings = line.split("\\$");
String title = strings[0];
String format = strings[1];
boolean onLoan = Boolean.parseBoolean(strings[2]);
String loanedTo = strings[3];
String dateLoaned = strings[4];
MediaItem superItem = new MediaItem(title,format, onLoan,loanedTo,dateLoaned);
items.add(superItem);
}
fileReader.close();
}catch ( IOException e ) {
e.printStackTrace();
}
}

String line = // input line e.g. "Aliens$Bluray$true$John$Monday"
String[] strings = line.split("\\$"); // use regex matching "$" to split
String title = strings[0];
String formatt = strings[1];
boolean onLoan = Boolean.parseBoolean(strings[2]);
String loanedTo = strings[3];
String dateLoaned = strings[4];
// TODO: create object from those values
Maybe you need to handle null differently (in case you want the String "null" to be converted to null); note that you can't distinguish if null or "null" was saved.
This function converts "null" to null and returns the same string otherwise:
String convert(String s) {
return s.equals("null") ? null : s;
}
Reading the objects to an array
Since you don't know the number of elements before reading all lines, you have to work around that:
Write the number of objects in the file as first line, which would allow you to create the array before reading the first object. (Use Integer.parseInt(String) to convert the first line to int):
public void save() {
String[] array2 = listForSave();
PrintWriter printer = null;
try {
printer = new PrintWriter(file);
printer.println(array2.length);
for (String o : array2) {
printer.println(o);
}
printer.close();
} catch ( IOException e ) {
e.printStackTrace();
}
}
public void open(){
try{
FileReader fileReader = new FileReader(file);
BufferedReader bufferedReader = new BufferedReader(fileReader);
StringBuffer stringBuffer = new StringBuffer();
int arraySize = Integer.parseInt(stringBuffer.readLine());
Object[] array = new Object[arraySize];
int index = 0;
String line;
while ((line = bufferedReader.readLine()) != null) {
// split line and create Object (see above)
Object o = // ...
array[index++] = o;
}
//...
}catch ( IOException e ) {
e.printStackTrace();
}
//...
}
or
Use a Collection, e.g. ArrayList to store the objects and use List.toArray(T[]) to get an array.

quick and dirty solution might be...
public void open(){
try{
ArrayList<Item> list = new ArrayList<Item>(); //Array of your ItemObject
FileReader fileReader = new FileReader(file);
BufferedReader bufferedReader = new BufferedReader(fileReader);
StringBuffer stringBuffer = new StringBuffer();
String line;
while ((line = bufferedReader.readLine()) != null) {
Item itm = new Item(); //New Item Object
String [] splitLine = line.split("\\$");
item.title = splitLine[0];
item.format = splitLine[1];
item.onLoan = Boolean.parseBoolean(splitLine[2]);
item.loanedTo = splitLine[3];
item.dateLoaned = splitLine[4];
list.add(itm);
stringBuffer.append(line);
stringBuffer.append("\n");
}
fileReader.close();
System.out.println("Contents of file:");
System.out.println(stringBuffer.toString());
}catch ( IOException e ) {
e.printStackTrace();
}
}
But this is won't scale if you need to re-arrange or add new fields.

You could try this to "parse" every line of your file
String[] result = "StarWars$DVD$false$null$null".split("\\$");
for (int i=0; i<result.length; i++) {
String field = result[i]
... put the strings in your object ...
}

splitting of csv file based on column value in java

I want to split csv file into multiple csv files depending on column value.
Structure of csv file: Name,Id,Dept,Course
abc,1,CSE,Btech
fgj,2,EE,Btech
(Rows are not separated by ; at end)
If value of Dept is CSE or ME , write it to file1.csv, if value is ECE or EE write it to file2.csv and so on.
Can I use drools for this purpose? I don't know drools much.
Any help how it can be done?
This is what I have done yet:
public void run() {
String csvFile = "C:/csvFiles/file1.csv";
BufferedReader br = null;
BufferedWriter writer=null,writer2=null;
String line = "";
String cvsSplitBy = ",";
String FileName = "C:/csvFiles/file3.csv";
String FileName2 = "C:/csvFiles/file4.csv";
try {
writer = new BufferedWriter(new FileWriter(FileName));
writer2 = new BufferedWriter(new FileWriter(FileName2));
br = new BufferedReader(new FileReader(csvFile));
while ((line = br.readLine()) != null) {
String[] values=line.split(cvsSplitBy);
if(values[2].equals("CSE"))
{
writer.write(line);
}
else if(values[2].equals("ECE"))
{
writer2.write(line);
}
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
writer.flush();
writer.close();
writer2.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

1) First find column index using header row or if header is not present then by index
2) Follow below algorithm which will result map of key value where key is column by which split is performed
global resultMap;
Method add(key,row) {
data = (resultMap.containsKey(key))? resultMap.get(key):new ArrayList<String>();
data.add(row);
resultMap.put(key, data );
}
Method getSplittedMap(List rows) {
for (String currentRow : rows) {
add(key, currentRow);
}
return resultMap;
}
hope this helps.

FileOutputStream f_ECE = new FileOutputStream("provideloaction&filenamehere");
FileOutputStream f_CSE_ME = new FileOutputStream("provideloaction&filenamehere");
FileInputputStream fin = new FileinputStream("provideloaction&filenamehere");
int size = fin.available(); // find the length of file
byte b[] = new byte[size];
fin.read(b);
String s = new String(b); // file copied into string
String s1[] = s.split("\n");
for (int i = 0; i < s1.length; i++) {
String s3[] = s1[i].split(",")
if (s3[2].equals("ECE"))
f_ECE.write(s1.getBytes());
if (s3[2].equals("CSE") || s3.equals("EEE"))
f_CSE_ME.write(payload.getBytes());
}

very long string as a response of web service

I am getting a really long string as the response of the web service I am collecting it in the using the StringBuilder but I am unable to obtain the full value I also used StringBuffer but had no success.
Here is the code I am using:
private static String read(InputStream in ) throws IOException {
//StringBuilder sb = new StringBuilder(1000);
StringBuffer sb = new StringBuffer();
String s = "";
BufferedReader r = new BufferedReader(new InputStreamReader( in ), 1000);
for (String line = r.readLine(); line != null; line = r.readLine()) {
sb.append(line);
s += line;
} in .close();
System.out.println("Response from Input Stream Reader >>>" + sb.toString());
System.out.println("Response from Input S >>>>>>>>>>>>" + s);
return sb.toString();
}
Any help is appreciated.

You can also split the string in array of strings in order to see all of them
String delimiter = "put a delimiter here e.g.: \n";
String[] datas=sb.toString().split(delimiter);
for(String string datas){
System.out.println("Response from Input S >>>>>>>>>>>>" + string);
}

The String may not print entirely to the console, but it is actually there. Save it to a file in order to see it.

I do not think that your input is too big for a String, but only not shown to the console because it doesn't accept too long lines. Anyways, here is the solution for a really huge input as characters:
private static String[] readHugeStream(InputStream in) throws IOException {
LinkedList<String> dataList = new LinkedList<>();
boolean finished = false;
//
BufferedReader r = new BufferedReader(new InputStreamReader(in), 0xFFFFFF);
String line = r.readLine();
while (!finished) {
int lengthRead = 0;
StringBuilder sb = new StringBuilder();
while (!finished) {
line = r.readLine();
if (line == null) {
finished = true;
} else {
lengthRead += line.length();
if (lengthRead == Integer.MAX_VALUE) {
break;
}
sb.append(line);
}
}
if (sb.length() != 0) {
dataList.add(sb.toString());
}
}
in.close();
String[] data = dataList.toArray(new String[]{});
///
return data;
}
public static void main(String[] args) {
try {
String[] data = readHugeStream(new FileInputStream("<big file>"));
} catch (IOException ex) {
Logger.getLogger(StackoverflowStringLong.class.getName()).log(Level.SEVERE, null, ex);
} catch (OutOfMemoryError ex) {
System.out.println("out of memory...");
}
}

System.out.println() does not print all the characters , it can display only limited number of characters in console. You can create a file in SD card and copy the string there as a text document to check your exact response.
try
{
File root = new File(Environment.getExternalStorageDirectory(), "Responsefromserver");
if (!root.exists())
{
root.mkdirs();
}
File gpxfile = new File(root, "response.txt");
FileWriter writer = new FileWriter(gpxfile);
writer.append(totalResponse);
writer.flush();
writer.close();
}
catch(IOException e)
{
System.out.println("Error:::::::::::::"+e.getMessage());
throw e;
}