Develop Reference

Need to count the number of files located within each zip file in a directory folder in JAVA

I have a folder which has a series of Zip files within it. I am trying to iterate through the folder and count the number of files that are in each zip file. I have created two pieces of code, I am just not sure how to put them together to get my desired results. Both codes are placed into try/catch blocks and they both work perfectly independently. This is using Eclipse, written in Java.
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.stream.Collectors;
import java.util.zip.ZipFile;
import java.io.File;
import java.util.List;
public class KZF {
public static void main(String[] args) {
// TODO Auto-generated method stub
// Try/Catch Block counts the number of files within a given zip file
try {
ZipFile zipFile = new ZipFile(
"C:\\Users\\username\\Documents\\Temp\\AllKo\\Policy.zip");
int NumberOfFiles = zipFile.size() - 1;
// String name = zipFile.getName();
Path path = Paths
.get("C:\\Users\\username\\Documents\\Temp\\AllKo\\Policy.zip");
Path filename = path.getFileName();
System.out.print("The number of files in: ");
// System.out.print(name);
System.out.print(filename.toString());
System.out.print(" are: ");
System.out.print(NumberOfFiles + " file(s)");
zipFile.close();
}
catch (IOException ioe) {
System.out.println("Error opening zip file" + ioe);
}
// ----------------------------------------------------------------------------------------------------------
// Creates list of every file specified folder
String dirLocation = "C:\\Users\\username\\Documents\\Temp\\AllKo";
try { List<File> files = Files.list(Paths.get(dirLocation))
.map(Path::toFile) .collect(Collectors.toList());
files.forEach(System.out::println);
} catch(IOException e) { Error }
}
}

You must be careful about opening/closing streams, so you can try something like this:
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.util.Enumeration;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
public class KZF
{
static int findNumberOfFiles(File file) {
try (ZipFile zipFile = new ZipFile(file)) {
return zipFile.stream().filter(z -> !z.isDirectory()).count();
} catch (Exception e) {
return -1;
}
}
static String createInfo(File file) {
int tot = findNumberOfFiles(file);
return (file.getName() + ": " + (tot >= 0 ? tot + " files" : "Error reading zip file"));
}
public static void main(String[] args) throws IOException {
String dirLocation = "C:\\Users\\username\\Documents\\Temp\\AllKo";
try (Stream<Path> files = Files.list(Paths.get(dirLocation))) {
files
.filter(path -> path.toFile().isFile())
.filter(path -> path.toString().toLowerCase().endsWith(".zip"))
.map(Path::toFile)
.map(KZF::createInfo)
.forEach(System.out::println);
}
}
}

Java IO outperforms Java NIO when it comes to file reading

I believed that the new nio package would outperform the old io package when it comes to the time required to read the contents of a file. However, based on my results, io package seems to outperform nio package. Here's my test:
import java.io.*;
import java.lang.reflect.Array;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Files;
import java.util.ArrayList;
import java.util.List;
public class FileTestingOne {
public static void main(String[] args) {
long startTime = System.nanoTime();
File file = new File("hey2.txt");
try {
byte[] a = direct(file);
String s = new String(a);
}
catch (IOException err) {
err.printStackTrace();
}
long endTime = System.nanoTime();
long totalTime = (endTime - startTime);
System.out.println(totalTime);
}
public static ByteBuffer readFile_NIO(File file) throws IOException {
RandomAccessFile rFile = new RandomAccessFile(file.getName(), "rw");
FileChannel inChannel = rFile.getChannel();
ByteBuffer _buffer = ByteBuffer.allocate(1024);
int bytesRead = inChannel.read(_buffer);
while (bytesRead != -1) {
_buffer.flip();
while (_buffer.hasRemaining()) {
byte b = _buffer.get();
}
_buffer.clear();
bytesRead = inChannel.read(_buffer);
}
inChannel.close();
rFile.close();
return _buffer;
}
public static byte[] direct(File file) throws IOException {
byte[] buffer = Files.readAllBytes(file.toPath());
return buffer;
}
public static byte[] readFile_IO(File file) throws IOException {
byte[] _buffer = new byte[(int) file.length()];
InputStream in = null;
try {
in = new FileInputStream(file);
if ( in.read(_buffer) == -1 ) {
throw new IOException(
"EOF reached while reading file. File is probably empty");
}
}
finally {
try {
if (in != null)
in.close();
}
catch (IOException err) {
// TODO Logging
err.printStackTrace();
}
}
return _buffer;
}
}
// Small file
//7566395 -> readFile_NIO
//10790558 -> direct
//707775 -> readFile_IO
// Large file
//9228099 -> readFile_NIO
//737674 -> readFile_IO
//10903324 -> direct
// Very large file
//13700005 -> readFile_NIO
//2837188 -> readFile_IO
//11020507 -> direct
Results are:
Small file:
nio implementation: 7,566,395ns
io implementation: 707,775ns
direct implementation: 10,790,558ns
Large file:
nio implementation: 9,228,099ns
io implementation: 737,674ns
direct implementation: 10,903,324ns
Very large file:
nio implementation: 13,700,005ns
io implementation: 2,837,188ns
direct implementation: 11,020,507ns
I wanted to ask this question because (I believe) nio package is non-blocking, thus it needs to be faster, right?
Thank you,
Edit:
Changed ms to ns

Memory mapped files (or MappedByteBuffer) are a part of Java NIO and could help improve performance.
The non-blocking in Java NIO means that a thread does not have to wait for the next data to read. It does not necessarily affect performance of a full operation (like reading and processing a file) at all.

using Java arraylist for storing data from scan from file

I am new to java, but not coding. I am trying to figure out java because it's part of my class this term and I am having a really hard problem grasping the idea of it and implementing things in java.
my problem Is that I am not sure if I am correctly using the arraylist to grab data from the scan of the file and input it into a arraylist to sort and print at a later time. I am just having issues picking up on java any help would be great since I am new to java.
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.regex.Pattern;
import java.util.ArrayList;
import java.util.*;
public class MissionCount
{
private static ArrayList<String> list = new ArrayList<String>();
// returns an InputStream that gets data from the named file
private static InputStream getFileInputStream(String fileName) throws Exception {
InputStream inputStream;
try {
inputStream = new FileInputStream(new File(fileName));
}
catch (FileNotFoundException e) { // no file with this name exists
inputStream = null;
throw new Exception("unable to open the file -- " + e.getMessage());
}
return inputStream;
}
public static void main(String[] args) {
if (args.length != 1) {
System.out.println("USage: MissionCount <datafile>");
//System.exit(1);
}
try {
System.out.printf("CS261 - MissionCount - Chad Dreher%n%n");
int crewcount = 0;
int misscount = 0;
InputStream log = getFileInputStream(args[0]);
Scanner sc = new Scanner(log);
sc.useDelimiter(Pattern.compile(",|\n"));
while (sc.hasNext()) {
String crewMember = sc.next();
list.add(crewMember);
String mission = sc.next();
list.add(mission);
}
sc.close();
// Add code to print the report here
}catch (Exception e) {
System.out.println("Error: " + e.getMessage());
}
}
}

InputStream log = getFileInputStream(args[0]);
Change that line to as follows :-
File log = new File(args[0])
that should work!

Read different portion of a file with multiple threads in Java

I have a 10GB PDF file that I would like to break up into 10 files each 1GB in size. I need to do this operation in parallel, which means spinning 10 threads which each starts from a different position and read up to 1GB of data and write to a file. Basically the final result should be 10 files that each contain a portion of the original 10GB file.
I looked at FileChannel, but the position is shared, so once I modify the position in one thread, it impacts the other thread. I also looked at AsynchronousFileChannel in Java 7 but I'm not sure if that's the way to go. I appreciate any suggestion on this issue.
I wrote this simple program that reads a small text file to test the FileChannel idea, doesn't seem to work for what I'm trying to achieve.
package org.cas.filesplit;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Path;
import java.nio.file.Paths;
public class ConcurrentRead implements Runnable {
private int myPosition = 0;
public int getPosition() {
return myPosition;
}
public void setPosition(int position) {
this.myPosition = position;
}
static final String filePath = "C:\\Users\\temp.txt";
#Override
public void run() {
try {
readFile();
} catch (IOException e) {
e.printStackTrace();
}
}
private void readFile() throws IOException {
Path path = Paths.get(filePath);
FileChannel fileChannel = FileChannel.open(path);
fileChannel.position(myPosition);
ByteBuffer buffer = ByteBuffer.allocate(8);
int noOfBytesRead = fileChannel.read(buffer);
while (noOfBytesRead != -1) {
buffer.flip();
System.out.println("Thread - " + Thread.currentThread().getId());
while (buffer.hasRemaining()) {
System.out.print((char) buffer.get());
}
System.out.println(" ");
buffer.clear();
noOfBytesRead = fileChannel.read(buffer);
}
fileChannel.close();
}
}

I would like to print the output that comes on the console to a text file. I tried the below but it didn't workout. Could anyone please look at this?

The below is the code that I tried to print the output that comes on the console to a text file. The main idea of the code is fetch values from a csv file and print the output to a text file. Could someone let me know how this can be achieved.
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import com.csvreader.CsvReader;
public class projectInfo {
public static void main(String[] args) {
StringBuffer buffer = new StringBuffer();
Connection conn;
int count = 0;
String sampleIddisp = null;
String sample_name = null;
String compound_name = null;
String registration_date = null;
}
products.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
System.out.println("\n Total number of records processed:" + count);
}
}
}

You never place any content in your StringBuffer buffer, so it is empty when you write it to file:
bw.write(buffer.toString());
buffer could potentially consume a large amount of memory here.
A better approach to writing the data to file would be to write the data as you read it from the database:
while (rs.next()) {
sampleIddisp = rs.getString(1);
...
bw.write(....);
}