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I am dividing my file into chunks but only problem i am facing is,
i have .srt file, but while doing chunks, it's cutting the characters i.e in first .srt file it's like 00:26:20,230 --> . in next file it continuing the next time stamp 00:27:40,343.
I need to check the timestamp to be complete and then next full subtitle sentence too. i.e if it's cutting the subtitle timesstamp or dialogue in in file, that tect to be append to next file. Please suggest me how can i achieve.
I am trying like below,
String FilePath = "/Users/meh/Desktop/escapeplan.srt";
FileInputStream fin = new FileInputStream(FilePath);
System.out.println("size: " +fin.getChannel().size());
long abc = 0l;
abc = (fin.getChannel().size())/3;
System.out.println("6: " +abc);
System.out.println("abc: " +abc);
//FilePath = args[1];
File filename = new File(FilePath);
long splitFileSize = 0,bytefileSize=0;
if (filename.exists()) {
try {
//bytefileSize = Long.parseLong(args[2]);
splitFileSize = abc;
Splitme spObj = new Splitme();
spObj.split(FilePath, (long) splitFileSize);
spObj = null;
} catch (Exception e) {
e.printStackTrace();
}
} else {
System.out.println("File Not Found....");
}
public void split(String FilePath, long splitlen) {
long leninfile = 0, leng = 0;
int count = 1, data;
try {
File filename = new File(FilePath);
InputStream infile = new BufferedInputStream(new FileInputStream(filename));
data = infile.read();
System.out.println("data");
System.out.println(data);
while (data != -1) {
filename = new File("/Users/meh/Documents/srt" + count + ".srt");
//RandomAccessFile outfile = new RandomAccessFile(filename, "rw");
OutputStream outfile = new BufferedOutputStream(new FileOutputStream(filename));
while (data != -1 && leng < splitlen) {
outfile.write(data);
leng++;
data = infile.read();
}
leninfile += leng;
leng = 0;
outfile.close();
changeTimeStamp(filename, count);
count++;
}
} catch (Exception e) {
e.printStackTrace();
}
}
i am trying to check the time stamp is in correct format or not. Then i need to check next line to be a dialogue and then the next line to be empty line. then it can stop chunk or else it should append the text from the previous chunk to next chunk file in the beginning of line . so that it may get in correct format.
I tried checking the format like,
while ((strLine = br.readLine()) != null) {
String[] atoms = strLine.split(" --> ");
if (atoms.length == 1) {
out.write(strLine + "\n");
} else {
String startTS = atoms[0];
String endTS = atoms[1];
System.out.print("sri atmos start" + startTS);
System.out.print("sri atmos end" + endTS);
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss,SSS");
sdf.setLenient(false);
try
{
sdf.parse(startTS);
sdf.parse(endTS);
System.out.println("Valid time");
System.out.println("File path" + srcFileNm);
}
catch(Exception e) {
System.out.println("Invalid time");
System.out.println("Exception start" + startTS);
System.out.println("Exception end" + endTS);
}
}
some screens of my output chunks,
Help me how can i make this possible.
I think you should change approach, and fully use basic I/O methods. I tried to encapsulate logic in a small class, that produces a triple with id, msecs and a list of subtitles (if I'm not wrong, you can have more than a line). Then I leaved the remainder externally. Chunker is a class that reads a triple (class Three) from file, so that you can manage it and write it somewhere.
This is just a "quick&dirty" idea that you can refine, but it should work.
package org.norsam.stackoverflow;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class Chunker
{
BufferedReader r;
int chunk = 0;
File dir;
public Chunker(File dir, String filename) throws IOException
{
File f = new File(dir, filename);
this.dir = dir;
this.r = new BufferedReader(new FileReader(f));
}
public Three readThree() throws IOException
{
Integer id = Integer.parseInt(r.readLine());
String msecs = r.readLine();
String s = null;
List<String> srt = new ArrayList<>();
while (!(s = r.readLine().trim()).isEmpty()) {
srt.add(s);
}
return new Three(id, msecs, srt);
}
class Three
{
Integer id;
String msecs;
List<String> srts;
Three(Integer id, String msecs, List<String> srts)
{
this.id = id;
this.msecs = msecs;
this.srts = srts;
}
Three doSomething() {
// here you can do something with your data,
// e.g. split msecs on "-->" and check times
return this;
}
void write(BufferedWriter r) throws IOException
{
r.write(id);
r.newLine();
r.write(msecs);
r.newLine();
for (String s : srts) {
r.write(s);
r.newLine();
}
r.newLine();
}
}
public static void main(String[] args) throws IOException
{
String baseDir = "/dir/where/resides/srt";
String filename = "filename.srt";
int elemPerChunk = 50;
int fileNum = 0;
File dir = new File(baseDir);
Chunker chunker = new Chunker(dir, filename);
boolean completed = false;
while (!completed) {
int srtCount = 0;
File f = new File(baseDir, "ch." + (fileNum++) + "." + filename);
BufferedWriter w = new BufferedWriter(new FileWriter(f));
try {
while (srtCount++ < elemPerChunk) {
chunker.readThree().doSomething().write(w);
}
} catch (NullPointerException e) {
completed = true;
}
w.close();
}
}
}
I'm going to pass my data from MongoDB to Neo4j.
So, I exported my MongoDB documents in .csv. As you can read here I have a problem with the array uniform.
So I wrote a java program to fix this problem.
Here is the .csv exported from MongoDB (note the different about uniform array):
_id,official_name,common_name,country,started_by.day,started_by.month,started_by.year,championship,stadium.name,stadium.capacity,palmares.first_prize,palmares.second_prize,palmares.third_prize,palmares.fourth_prize,average_age,squad_value,foreigners,uniform
0,yaDIXxLAOV,WWYWLqPcYM,QsVwiNmeGl,7,9,1479,oYKGgstIMv,qskcxizCkd,8560,10,25,9,29,16,58,6,"[""first_colour"",""second_colour"",""third_colour""]"
Here is how it must be to import in Neo4j:
_id,official_name,common_name,country,started_by.day,started_by.month,started_by.year,championship,stadium.name,stadium.capacity,palmares.first_prize,palmares.second_prize,palmares.third_prize,palmares.fourth_prize,average_age,squad_value,foreigners,uniform.0,uniform.1,uniform.2
0,yaDIXxLAOV,WWYWLqPcYM,QsVwiNmeGl,7,9,1479,oYKGgstIMv,qskcxizCkd,8560,10,25,9,29,16,58,6,first_colour,second_colour,third_colour
My code works, but I have to convert 500k line of the .csv file and the program it is too much slow(it's still working after 20 minutes :/):
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
public class ConvertireCSV {
public static void main(String[] args) throws IOException {
FileReader f;
f=new FileReader("output.csv");
BufferedReader b;
b=new BufferedReader(f);
String firstLine= b.readLine();
int uniform = firstLine.indexOf("uniform");
firstLine=firstLine.substring(0, uniform);
firstLine = firstLine + "uniform.0,uniform.1,uniform.2\n";
String line="";
String csv="";
while(true) {
line=b.readLine();
if(line==null)
break;
int u = line.indexOf("\"[");
line=line.substring(0, u);
line=line + "first_colour,second_colour,third_colour \n";
csv=csv+line;
}
File file = new File("outputForNeo4j.csv");
if(file.createNewFile()) {
PrintWriter pw = new PrintWriter(file);
pw.println(firstLine + csv);
System.out.println("New file \"outputForNeo4j.csv\" created.");
pw.flush();
pw.close();
}
}
}
How can I make it faster?
Okay some basic ways to improve your code:
Make sure that your variables got the minimal scope required. If you don't need line outside your loop, don't declare it outside your loop.
Concatenation of simple strings is in general slow. Use a StringBuilder to speed things to there.
Why are you buffering the string anyway? Seems like a waste of memory. Just open the output stream to your target file and write the lines to the new file as you process them.
Examples:
I don't think you need a example on the first point.
For the second things could look like this:
...
StringBuilder csv = new StringBuilder();
while(true) {
...
csv.append(line);
}
...
if(file.createNewFile()) {
...
pw.println(firstLine + csv.toString());
...
}
For the third point the rewriting would be a little more extensive:
public static void main(String[] args) throws IOException {
FileReader f;
f=new FileReader("output.csv");
BufferedReader b;
b=new BufferedReader(f);
String firstLine= b.readLine();
int uniform = firstLine.indexOf("uniform");
firstLine=firstLine.substring(0, uniform);
firstLine = firstLine + "uniform.0,uniform.1,uniform.2\n";
File file = new File("outputForNeo4j.csv");
if(!file.createNewFile()) {
// all work would be for nothing! Bailing out.
return;
}
PrintWriter pw = new PrintWriter(file);
pw.print(firstLine);
while(true) {
String line=b.readLine();
if(line==null)
break;
int u = line.indexOf("\"[");
line=line.substring(0, u);
line=line + "first_colour,second_colour,third_colour \n";
pw.print(line);
}
System.out.println("New file \"outputForNeo4j.csv\" created.");
pw.flush();
pw.close();
b.close()
}
csv=csv+line;
string concatenation is expensive operation. I would suggest using bufferedWriter.
something like this:
FileReader f;
f=new FileReader("output.csv");
BufferedReader b;
BufferedWriter out;
b=new BufferedReader(f);
try{
out = new BufferedWriter(new FileWriter("outputForNeo4j.csv"));
} catch(Exception e){
//cannot create file
}
System.out.println("New file \"outputForNeo4j.csv\" created.");
String firstLine= b.readLine();
int uniform = firstLine.indexOf("uniform");
firstLine=firstLine.substring(0, uniform);
firstLine = firstLine + "uniform.0,uniform.1,uniform.2\n";
String line="";
String csv="";
out.write(firstLine);
while(true) {
line=b.readLine();
if(line==null)
break;
int u = line.indexOf("\"[");
line=line.substring(0, u);
line=line + "first_colour,second_colour,third_colour \n";
out.write(line);
}
out.flush();
}
Results :
test0 : Runs: 241 iterations ,avarage milis = 246
test1 : Runs: 249 iterations ,avarage milis = 118
test2 : Runs: 269 iterations ,avarage milis = 5
test3 : Runs: 241 iterations ,avarage milis = 2
import java.io.*;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Random;
public class Tester {
private static final String filePath = "c:\\bigFile.txt";
//private static final String filePath = "c:\\bigfileNewLine.txt";
private static final int numOfMethods = 4;
private static final int numOfIter = 1000;
public Tester() throws NoSuchMethodException {
System.out.println("Tester.Tester");
int[] milisArr = new int [numOfMethods];
int[] actualRun = new int [numOfMethods];
Random rnd = new Random(System.currentTimeMillis());
Long startMs = 0l, endMs = 0l;
Method[] method = new Method[numOfMethods];
for (int i = 0; i < numOfMethods; i++)
method[i] = this.getClass().getMethod("test" + i);
int testCount = 0;
while (testCount++ < numOfIter) {
int testMethod = rnd.nextInt(numOfMethods);
Method m = method[testMethod];
try {
System.gc();
startMs = System.currentTimeMillis();
String retval = (String) m.invoke(null);
endMs = System.currentTimeMillis();
} catch (IllegalAccessException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
} catch (InvocationTargetException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
milisArr[testMethod] += (endMs - startMs);
actualRun[testMethod]++;
System.out.println("Test name: " + m.getName() + " testCount=" + testCount + " Of " + numOfIter + " iteration, Total time :" + (endMs - startMs) / 1000.0 + " seconds");
}
System.out.println("Test Summery :");
for (int i = 0; i < numOfMethods; i++)
System.out.println("test" + i + " : Runs: " + actualRun[i] + " iterations ,avarage milis = " + milisArr[i]/numOfIter);
}
public static String test0() throws IOException {
InputStream file = getInputStream();
StringBuffer textBuffer = new StringBuffer();
int c;
while ((c = file.read()) != -1)
textBuffer.append((char) c);
file.close();
return textBuffer.toString();
}
public static String test1() throws IOException {
Reader reader = new FileReader(new File(filePath));
BufferedReader br = new BufferedReader(reader);
String line = br.readLine();
String result = line;
while (line != null) {
line = br.readLine();
if (line == null) {
} else {
result = result + "\n" + line;
}
}
br.close();
reader.close();
return result;
}
public static String test2() throws IOException {
byte[] buf = new byte[1024];
int l;
InputStream is = getInputStream();
StringBuffer tmpBuf = new StringBuffer();
while ((l = is.read(buf)) != -1) {
tmpBuf.append(new String(buf, 0, l));
}
is.close();
return tmpBuf.toString();
}
public static String test3() throws IOException {
File source = new File(filePath);
final DataInputStream dis = new DataInputStream(new BufferedInputStream(new FileInputStream(source)));
final byte[] buffer = new byte[(int) source.length()];
dis.readFully(buffer);
dis.close();
return new String(buffer, "UTF-8");
}
private static InputStream getInputStream() {
try {
return new FileInputStream(filePath);
} catch (FileNotFoundException e) {
e.printStackTrace();
return null;
}
}
public static void main(String[] args) {
try {
new Tester();
} catch (NoSuchMethodException e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
}
}
I have a file which I would like to read in Java and split this file into n (user input) output files. Here is how I read the file:
int n = 4;
BufferedReader br = new BufferedReader(new FileReader("file.csv"));
try {
String line = br.readLine();
while (line != null) {
line = br.readLine();
}
} finally {
br.close();
}
How do I split the file - file.csv into n files?
Note - Since the number of entries in the file are of the order of 100k, I can't store the file content into an array and then split it and save into multiple files.
Since one file can be very large, each split file could be large as well.
Example:
Source File Size: 5GB
Num Splits: 5: Destination
File Size: 1GB each (5 files)
There is no way to read this large split chunk in one go, even if we have such a memory. Basically for each split we can read a fix size byte-array which we know should be feasible in terms of performance as well memory.
NumSplits: 10 MaxReadBytes: 8KB
public static void main(String[] args) throws Exception
{
RandomAccessFile raf = new RandomAccessFile("test.csv", "r");
long numSplits = 10; //from user input, extract it from args
long sourceSize = raf.length();
long bytesPerSplit = sourceSize/numSplits ;
long remainingBytes = sourceSize % numSplits;
int maxReadBufferSize = 8 * 1024; //8KB
for(int destIx=1; destIx <= numSplits; destIx++) {
BufferedOutputStream bw = new BufferedOutputStream(new FileOutputStream("split."+destIx));
if(bytesPerSplit > maxReadBufferSize) {
long numReads = bytesPerSplit/maxReadBufferSize;
long numRemainingRead = bytesPerSplit % maxReadBufferSize;
for(int i=0; i<numReads; i++) {
readWrite(raf, bw, maxReadBufferSize);
}
if(numRemainingRead > 0) {
readWrite(raf, bw, numRemainingRead);
}
}else {
readWrite(raf, bw, bytesPerSplit);
}
bw.close();
}
if(remainingBytes > 0) {
BufferedOutputStream bw = new BufferedOutputStream(new FileOutputStream("split."+(numSplits+1)));
readWrite(raf, bw, remainingBytes);
bw.close();
}
raf.close();
}
static void readWrite(RandomAccessFile raf, BufferedOutputStream bw, long numBytes) throws IOException {
byte[] buf = new byte[(int) numBytes];
int val = raf.read(buf);
if(val != -1) {
bw.write(buf);
}
}
import java.io.*;
import java.util.Scanner;
public class split {
public static void main(String args[])
{
try{
// Reading file and getting no. of files to be generated
String inputfile = "C:/test.txt"; // Source File Name.
double nol = 2000.0; // No. of lines to be split and saved in each output file.
File file = new File(inputfile);
Scanner scanner = new Scanner(file);
int count = 0;
while (scanner.hasNextLine())
{
scanner.nextLine();
count++;
}
System.out.println("Lines in the file: " + count); // Displays no. of lines in the input file.
double temp = (count/nol);
int temp1=(int)temp;
int nof=0;
if(temp1==temp)
{
nof=temp1;
}
else
{
nof=temp1+1;
}
System.out.println("No. of files to be generated :"+nof); // Displays no. of files to be generated.
//---------------------------------------------------------------------------------------------------------
// Actual splitting of file into smaller files
FileInputStream fstream = new FileInputStream(inputfile); DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in)); String strLine;
for (int j=1;j<=nof;j++)
{
FileWriter fstream1 = new FileWriter("C:/New Folder/File"+j+".txt"); // Destination File Location
BufferedWriter out = new BufferedWriter(fstream1);
for (int i=1;i<=nol;i++)
{
strLine = br.readLine();
if (strLine!= null)
{
out.write(strLine);
if(i!=nol)
{
out.newLine();
}
}
}
out.close();
}
in.close();
}catch (Exception e)
{
System.err.println("Error: " + e.getMessage());
}
}
}
Though its a old question but for reference I am listing out the code which I used to split large files to any sizes and it works with any Java versions above 1.4 .
Sample Split and Join blocks were like below:
public void join(String FilePath) {
long leninfile = 0, leng = 0;
int count = 1, data = 0;
try {
File filename = new File(FilePath);
//RandomAccessFile outfile = new RandomAccessFile(filename,"rw");
OutputStream outfile = new BufferedOutputStream(new FileOutputStream(filename));
while (true) {
filename = new File(FilePath + count + ".sp");
if (filename.exists()) {
//RandomAccessFile infile = new RandomAccessFile(filename,"r");
InputStream infile = new BufferedInputStream(new FileInputStream(filename));
data = infile.read();
while (data != -1) {
outfile.write(data);
data = infile.read();
}
leng++;
infile.close();
count++;
} else {
break;
}
}
outfile.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public void split(String FilePath, long splitlen) {
long leninfile = 0, leng = 0;
int count = 1, data;
try {
File filename = new File(FilePath);
//RandomAccessFile infile = new RandomAccessFile(filename, "r");
InputStream infile = new BufferedInputStream(new FileInputStream(filename));
data = infile.read();
while (data != -1) {
filename = new File(FilePath + count + ".sp");
//RandomAccessFile outfile = new RandomAccessFile(filename, "rw");
OutputStream outfile = new BufferedOutputStream(new FileOutputStream(filename));
while (data != -1 && leng < splitlen) {
outfile.write(data);
leng++;
data = infile.read();
}
leninfile += leng;
leng = 0;
outfile.close();
count++;
}
} catch (Exception e) {
e.printStackTrace();
}
}
Complete java code available here in File Split in Java Program link.
a clean solution to edit.
this solution involves loading the entire file into memory.
set all line of a file in List<String> rowsOfFile;
edit maxSizeFile to choice max size of a single file splitted
public void splitFile(File fileToSplit) throws IOException {
long maxSizeFile = 10000000 // 10mb
StringBuilder buffer = new StringBuilder((int) maxSizeFile);
int sizeOfRows = 0;
int recurrence = 0;
String fileName;
List<String> rowsOfFile;
rowsOfFile = Files.readAllLines(fileToSplit.toPath(), Charset.defaultCharset());
for (String row : rowsOfFile) {
buffer.append(row);
numOfRow++;
sizeOfRows += row.getBytes(StandardCharsets.UTF_8).length;
if (sizeOfRows >= maxSizeFile) {
fileName = generateFileName(recurrence);
File newFile = new File(fileName);
try (PrintWriter writer = new PrintWriter(newFile)) {
writer.println(buffer.toString());
}
recurrence++;
sizeOfRows = 0;
buffer = new StringBuilder();
}
}
// last rows
if (sizeOfRows > 0) {
fileName = generateFileName(recurrence);
File newFile = createFile(fileName);
try (PrintWriter writer = new PrintWriter(newFile)) {
writer.println(buffer.toString());
}
}
Files.delete(fileToSplit.toPath());
}
method to generate Name of file:
public String generateFileName(int numFile) {
String extension = ".txt";
return "myFile" + numFile + extension;
}
Have a counter to count no of entries. Let's say one entry per line.
step1: Initially create new subfile, set counter=0;
step2: increment counter as you read each entry from source file to buffer
step3: when counter reaches limit to number of entries that you want to write in each sub file, flush contents of buffer to subfile. close the subfile
step4 : jump to step1 till you have data in source file to read from
There's no need to loop twice through the file. You could estimate the size of each chunk as the source file size divided by number of chunks needed. Then you just stop filling each cunk with data as it's size exceeds estimated.
Here is one that worked for me and I used it to split 10GB file. it also enables you to add a header and a footer. very useful when splitting document based format such as XML and JSON because you need to add document wrapper in the new split files.
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
public class FileSpliter
{
public static void main(String[] args) throws IOException
{
splitTextFiles("D:\\xref.csx", 750000, "", "", null);
}
public static void splitTextFiles(String fileName, int maxRows, String header, String footer, String targetDir) throws IOException
{
File bigFile = new File(fileName);
int i = 1;
String ext = fileName.substring(fileName.lastIndexOf("."));
String fileNoExt = bigFile.getName().replace(ext, "");
File newDir = null;
if(targetDir != null)
{
newDir = new File(targetDir);
}
else
{
newDir = new File(bigFile.getParent() + "\\" + fileNoExt + "_split");
}
newDir.mkdirs();
try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName)))
{
String line = null;
int lineNum = 1;
Path splitFile = Paths.get(newDir.getPath() + "\\" + fileNoExt + "_" + String.format("%02d", i) + ext);
BufferedWriter writer = Files.newBufferedWriter(splitFile, StandardOpenOption.CREATE);
while ((line = reader.readLine()) != null)
{
if(lineNum == 1)
{
System.out.print("new file created '" + splitFile.toString());
if(header != null && header.length() > 0)
{
writer.append(header);
writer.newLine();
}
}
writer.append(line);
if (lineNum >= maxRows)
{
if(footer != null && footer.length() > 0)
{
writer.newLine();
writer.append(footer);
}
writer.close();
System.out.println(", " + lineNum + " lines written to file");
lineNum = 1;
i++;
splitFile = Paths.get(newDir.getPath() + "\\" + fileNoExt + "_" + String.format("%02d", i) + ext);
writer = Files.newBufferedWriter(splitFile, StandardOpenOption.CREATE);
}
else
{
writer.newLine();
lineNum++;
}
}
if(lineNum <= maxRows) // early exit
{
if(footer != null && footer.length() > 0)
{
writer.newLine();
lineNum++;
writer.append(footer);
}
}
writer.close();
System.out.println(", " + lineNum + " lines written to file");
}
System.out.println("file '" + bigFile.getName() + "' split into " + i + " files");
}
}
Below code used to split a big file into small files with lesser lines.
long linesWritten = 0;
int count = 1;
try {
File inputFile = new File(inputFilePath);
InputStream inputFileStream = new BufferedInputStream(new FileInputStream(inputFile));
BufferedReader reader = new BufferedReader(new InputStreamReader(inputFileStream));
String line = reader.readLine();
String fileName = inputFile.getName();
String outfileName = outputFolderPath + "\\" + fileName;
while (line != null) {
File outFile = new File(outfileName + "_" + count + ".split");
Writer writer = new OutputStreamWriter(new FileOutputStream(outFile));
while (line != null && linesWritten < linesPerSplit) {
writer.write(line);
line = reader.readLine();
linesWritten++;
}
writer.close();
linesWritten = 0;//next file
count++;//nect file count
}
reader.close();
} catch (Exception e) {
e.printStackTrace();
}
Split a file to multiple chunks (in memory operation), here I'm splitting any file to a size of 500kb(500000 bytes) :
public static List<ByteArrayOutputStream> splitFile(File f) {
List<ByteArrayOutputStream> datalist = new ArrayList<>();
try {
int sizeOfFiles = 500000;
byte[] buffer = new byte[sizeOfFiles];
try (FileInputStream fis = new FileInputStream(f); BufferedInputStream bis = new BufferedInputStream(fis)) {
int bytesAmount = 0;
while ((bytesAmount = bis.read(buffer)) > 0) {
try (OutputStream out = new ByteArrayOutputStream()) {
out.write(buffer, 0, bytesAmount);
out.flush();
datalist.add((ByteArrayOutputStream) out);
}
}
}
} catch (Exception e) {
//get the error
}
return datalist; }
I am a bit late to answer, But here's how I did it:
Approach:
First I determine how many bytes each of the individual files should contain then I split the large file by bytes. Only one file chunk worth of data is loaded into memory at a time.
Example:- if a 5 GB file is split into 10 files then only 500MB worth of bytes are loaded into memory at a time which are held in the buffer variable in the splitBySize method below.
Code Explaination:
The method splitFile first gets the number of bytes each of the individual file chunks should contain by calling the getSizeInBytes method, then it calls the splitBySize method which splits the large file by size (i..e maxChunkSize represents the number of bytes each of file chunks will contain).
public static List<File> splitFile(File largeFile, int noOfFiles) throws IOException {
return splitBySize(largeFile, getSizeInBytes(largeFile.length(), noOfFiles));
}
public static List<File> splitBySize(File largeFile, int maxChunkSize) throws IOException {
List<File> list = new ArrayList<>();
int numberOfFiles = 0;
try (InputStream in = Files.newInputStream(largeFile.toPath())) {
final byte[] buffer = new byte[maxChunkSize];
int dataRead = in.read(buffer);
while (dataRead > -1) {
list.add(stageLocally(buffer, dataRead));
numberOfFiles++;
dataRead = in.read(buffer);
}
}
System.out.println("Number of files generated: " + numberOfFiles);
return list;
}
private static int getSizeInBytes(long totalBytes, int numberOfFiles) {
if (totalBytes % numberOfFiles != 0) {
totalBytes = ((totalBytes / numberOfFiles) + 1)*numberOfFiles;
}
long x = totalBytes / numberOfFiles;
if (x > Integer.MAX_VALUE){
throw new NumberFormatException("Byte chunk too large");
}
return (int) x;
}
Full Code:
public class StackOverflow {
private static final String INPUT_FILE_PATH = "/Users/malkesingh/Downloads/5MB.zip";
private static final String TEMP_DIRECTORY = "/Users/malkesingh/temp";
public static void main(String[] args) throws IOException {
File input = new File(INPUT_FILE_PATH);
File outPut = fileJoin2(splitFile(input, 5));
try (InputStream in = Files.newInputStream(input.toPath()); InputStream out = Files.newInputStream(outPut.toPath())) {
System.out.println(IOUtils.contentEquals(in, out));
}
}
public static List<File> splitFile(File largeFile, int noOfFiles) throws IOException {
return splitBySize(largeFile, getSizeInBytes(largeFile.length(), noOfFiles));
}
public static List<File> splitBySize(File largeFile, int maxChunkSize) throws IOException {
List<File> list = new ArrayList<>();
int numberOfFiles = 0;
try (InputStream in = Files.newInputStream(largeFile.toPath())) {
final byte[] buffer = new byte[maxChunkSize];
int dataRead = in.read(buffer);
while (dataRead > -1) {
list.add(stageLocally(buffer, dataRead));
numberOfFiles++;
dataRead = in.read(buffer);
}
}
System.out.println("Number of files generated: " + numberOfFiles);
return list;
}
private static int getSizeInBytes(long totalBytes, int numberOfFiles) {
if (totalBytes % numberOfFiles != 0) {
totalBytes = ((totalBytes / numberOfFiles) + 1)*numberOfFiles;
}
long x = totalBytes / numberOfFiles;
if (x > Integer.MAX_VALUE){
throw new NumberFormatException("Byte chunk too large");
}
return (int) x;
}
private static File stageLocally(byte[] buffer, int length) throws IOException {
File outPutFile = File.createTempFile("temp-", "split", new File(TEMP_DIRECTORY));
try(FileOutputStream fos = new FileOutputStream(outPutFile)) {
fos.write(buffer, 0, length);
}
return outPutFile;
}
public static File fileJoin2(List<File> list) throws IOException {
File outPutFile = File.createTempFile("temp-", "unsplit", new File(TEMP_DIRECTORY));
FileOutputStream fos = new FileOutputStream(outPutFile);
for (File file : list) {
Files.copy(file.toPath(), fos);
}
fos.close();
return outPutFile;
}}
import java.util.*;
import java.io.*;
public class task13 {
public static void main(String[] args)throws IOException{
Scanner s =new Scanner(System.in);
System.out.print("Enter path:");
String a=s.next();
File f=new File(a+".txt");
Scanner st=new Scanner(f);
System.out.println(f.canRead()+"\n"+f.canWrite());
long l=f.length();
System.out.println("Length is:"+l);
System.out.print("Enter no.of partitions:");
int p=s.nextInt();
long x=l/p;
st.useDelimiter("\\Z");
String t=st.next();
int j=0;
System.out.println("Each File Length is:"+x);
for(int i=1;i<=p;i++){
File ft=new File(a+"-"+i+".txt");
ft.createNewFile();
int g=(j*(int)x);
int h=(j+1)*(int)x;
if(g<=l&&h<=l){
FileWriter fw=new FileWriter(a+"-"+i+".txt");
String v=t.substring(g,h);
fw.write(v);
j++;
fw.close();
}}
}}
Like a similar project I made, this project is reading characters from a txt file, reversing the order of the string and rewriting it to another txt file. But it keeps outputting my exception of "Something went wrong". Can anyone help me fix what is going wrong?
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;
public class ReverseFile
{
public static void main(String[] args) throws IOException
{
try{
String source = args[0];
String target = args[1];
File sourceFile=new File(source);
Scanner content=new Scanner(sourceFile);
PrintWriter pwriter =new PrintWriter(target);
while(content.hasNextLine())
{
String s=content.nextLine();
StringBuffer buffer = new StringBuffer(s);
buffer=buffer.reverse();
String rs=buffer.toString();
pwriter.println(rs);
}
content.close();
pwriter.close();
System.out.println("File is copied successful!");
}
catch(Exception e){
System.out.println("Something went wrong");
}
}
}
So here is the information from the stacktrace:
java.lang.ArrayIndexOutOfBoundsException: 0
at ReverseFile.main(ReverseFile.java:36)
i am not so sure about your environment, and how long the text might be. and i am also not so sure why you need a scanner?
anyway, here's my take on the problem, hope this helps you :)
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;
import java.io.Reader;
public class Reverse {
public static void main(String[] args) {
FileInputStream fis = null;
RandomAccessFile raf = null;
// by default, let's use utf-8
String characterEncoding = "utf-8";
// but if you pass an optional 3rd parameter, we use that
if(args.length==3) {
characterEncoding = args[2];
}
try{
// input file
File in = new File(args[0]);
fis = new FileInputStream(in);
// a reader, because it respects character encoding etc
Reader r = new InputStreamReader(fis,characterEncoding);
// an outputfile
File out = new File(args[1]);
// and a random access file of the same size as the input, so we can write in reverse order
raf = new RandomAccessFile(out, "rw");
raf.setLength(in.length());
// a buffer for the chars we want to read
char[] buff = new char[1];
// keep track of the current position (we're going backwards, so we start at the end)
long position = in.length();
// Reader.read will return -1 when it reached the end.
while((r.read(buff))>-1) {
// turn the character into bytes according to the character encoding
Character c = buff[0];
String s = c+"";
byte[] bBuff = s.getBytes(characterEncoding);
// go to the proper position in the random access file
position = position-bBuff.length;
raf.seek(position);
// write one or more bytes for the character
raf.write(bBuff);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
// clean up
try {
fis.close();
} catch (Exception e2) {
}
try {
raf.close();
} catch (Exception e2) {
}
}
}
}
You need to specify the filenames(source and target) on command-line, while running the program.
java ReverseFile source.txt target.txt
In your program, you try to read the name of files from command-line as
String source = args[0];
String target = args[1];
So if you do not specify those names there, java tries to access the array args at index 0 and 1 which are empty and you get ArrayIndexOutOfBoundsException.
here is ur error free solution to ur problem,u were using "Scanner" without importing "util"
package.here we go:-----------
import java.io.*;
import java.util.*;
public class ReverseFile
{
public static void main(String[] args) throws IOException
{
try{
File sourceFile=new File(args[0]);
Scanner content=new Scanner(sourceFile);
PrintWriter pwriter =new PrintWriter(args[1]);
while(content.hasNextLine())
{
String s=content.nextLine();
StringBuffer buffer = new StringBuffer(s);
buffer=buffer.reverse();
String rs=buffer.toString();
pwriter.println(rs);
}
content.close();
pwriter.close();
System.out.println("File is copied successful!");
}
catch(Exception e){
System.out.println("Something went wrong");
}
}
}
Just thought of a simple approach.
public class ReadFileReverse {
public int[] readByte(File _file) throws IOException {
FileInputStream source = new FileInputStream(_file);
int currentByte = source.available();
int readCount = 0;
int byteContainer[] = new int[currentByte];
while(readCount < currentByte){
byteContainer[readCount] = source.read();
readCount++;
}
source.close();
return byteContainer;
}
public void printReverse(int[] fileContent){
for(int byt=fileContent.length -1; byt >= 0 ; byt--){
System.out.print((char) fileContent[byt]);
}
}
public static void main(String[] args) throws IOException {
File fileToRead = new File("/README.txt");
ReadFileReverse demo = new ReadFileReverse ();
int[] readBytes = demo.readByte(fileToRead);
demo.printReverse(readBytes);
}
}
Here we are reading a file in string variable, then making a String Builder object to perform reverse operation efficiently, then printing
package com;
import java.io.FileReader;
public class Main {
public static void main(String[] args) {
try {
FileReader fr = new FileReader("D:\\newfile.txt");
String str = "";
int ch;
//reading characters in to string variable
while ((ch = fr.read()) != -1) {
str += Character.toString((char) ch);
}
System.out.println("Original String : " + str);
//converting string variable to String Builder object
StringBuilder sb = new StringBuilder(str);
//reversing the string and printing
System.out.println("Reverse order : " + sb.reverse());
fr.close();
} catch (Exception e) {
System.out.println("error");
}
}
}
Output:
This question already has answers here:
How can I download and save a file from the Internet using Java?
(23 answers)
Closed 4 years ago.
I am trying to write a code in java in which user provide a url link and the program take url link and download a web page as it is and save at particular location..same as save as... option available on webpage.
Please can anybody help me
Thanks in advance
// Sample URL : http://www.novell.com/coolsolutions/tools/downloads/ntradping.zip
import java.io.*;
import java.net.*;
public class UrlDownload {
final static int size = 1024;
public static void fileUrl(String fAddress, String localFileName, String destinationDir) {
OutputStream outStream = null;
URLConnection uCon = null;
InputStream is = null;
try {
URL url;
byte[] buf;
int byteRead, byteWritten = 0;
url = new URL(fAddress);
outStream = new BufferedOutputStream(new FileOutputStream(destinationDir + "\\" + localFileName));
uCon = url.openConnection();
is = uCon.getInputStream();
buf = new byte[size];
while ((byteRead = is.read(buf)) != -1) {
outStream.write(buf, 0, byteRead);
byteWritten += byteRead;
}
System.out.println("Downloaded Successfully.");
System.out.println("File name:\"" + localFileName + "\"\nNo ofbytes :" + byteWritten);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
is.close();
outStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static void fileDownload(String fAddress, String destinationDir) {
int slashIndex = fAddress.lastIndexOf('/');
int periodIndex = fAddress.lastIndexOf('.');
String fileName = fAddress.substring(slashIndex + 1);
if (periodIndex >= 1 && slashIndex >= 0 && slashIndex < fAddress.length() - 1) {
fileUrl(fAddress, fileName, destinationDir);
} else {
System.err.println("path or file name.");
}
}
public static void main(String[] args) {
if (args.length == 2) {
for (int i = 1; i < args.length; i++) {
fileDownload(args[i], args[0]);
}
} else {
}
}
}
It is working fully.
You can use Java URL API to get an input stream on the URL then read the from it and write through output stream on a file.
see read data from url, Write to file
Have a look at the HtmlParser. It has some features that will help you extract resources from a web page.