Develop Reference

Java - Pass a variable from user input to another java file

I am new to Java and I have a project to do, so I have a java file and the user have to choose from a listing of files in a directory. The input from user is saved in a variable (fileName). I want to use that variable in another java file for doing some other work. I searched online but didn't find any solution that works for me. Probably I've done something wrong.
code of the first file:
public class Director {
private static void copyFileUsingStream(File source, File dest) throws IOException {
InputStream is = null;
OutputStream os = null;
try {
is = new FileInputStream(source);
os = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
while ((length = is.read(buffer)) > 0) {
os.write(buffer, 0, length);
}
} finally {
is.close();
os.close();
}
}
public static void main(String[] args) throws IOException {
// Creates an array in which we will store the names of files and directories
String[] pathnames;
// Creates a new File instance by converting the given pathname string
// into an abstract pathname
File f = new File("C:\\Users\\miltos\\Desktop\\polimesa\\available_videos");
// Populates the array with names of files and directories
pathnames = f.list();
System.out.println("Files in the directory:");
// For each pathname in the pathnames array
for (String pathname : pathnames) {
// Print the names of files and directories
System.out.println(pathname);
}
Scanner myObj = new Scanner(System.in); // Create a Scanner object
System.out.println("Enter file name");
String fileName = myObj.nextLine();
File source = new File("C:\\Users\\miltos\\Desktop\\polimesa\\available_videos\\" + fileName);
File dest = new File("C:\\Users\\miltos\\Desktop\\polimesa\\raw_videos\\" + fileName);
copyFileUsingStream(source, dest);
}
}
code of the second file that i want to use the input:
public class TestFFMpeg {
static Logger log = LogManager.getLogger(TestFFMpeg.class);
public static void main(String[] args) {
FFmpeg ffmpeg = null;
FFprobe ffprobe = null;
try {
log.debug("Initialising FFMpegClient");
ffmpeg = new FFmpeg("C:\\Users\\miltos\\ffmpeg\\bin\\ffmpeg.exe");
ffprobe = new FFprobe("C:\\Users\\miltos\\ffmpeg\\bin\\ffprobe.exe");
} catch (IOException e) {
e.printStackTrace();
}
log.debug("Creating the transcoding");
FFmpegBuilder builder = new FFmpegBuilder()
.setInput("C:\\Users\\miltos\\Desktop\\polimesa\\raw_videos\\" + filename) //updated
.addOutput("C:\\Users\\miltos\\Desktop\\polimesa\\videos\\" + filename) //updated
.setVideoBitRate(200000)
.done();
log.debug("Creating the executor");
FFmpegExecutor executor = new FFmpegExecutor(ffmpeg, ffprobe);
log.debug("Starting the transcoding");
// Run a one-pass encode
executor.createJob(builder).run();
log.debug("Transcoding finished");
}
}

I created a variable names filename in class second also, which you will pass from the class one , while creating an object of class second like
TestFFMpeg obj = new TestFFMpeg();
obj.methodInSecondClass(filename);
Second Class :
public class TestFFMpeg {
static Logger log = LogManager.getLogger(TestFFMpeg.class);
public void methodInSecondClass(String filename){
FFmpeg ffmpeg = null;
FFprobe ffprobe = null;
try {
log.debug("Initialising FFMpegClient");
ffmpeg = new FFmpeg("C:\\Users\\miltos\\ffmpeg\\bin\\ffmpeg.exe");
ffprobe = new FFprobe("C:\\Users\\miltos\\ffmpeg\\bin\\ffprobe.exe");
} catch (IOException e) {
e.printStackTrace();
}
log.debug("Creating the transcoding");
FFmpegBuilder builder = new FFmpegBuilder()
.setInput("C:\\Users\\miltos\\Desktop\\polimesa\\available_videos\\"+filename) //this is where i want the same variable
.addOutput("C:\\Users\\miltos\\Desktop\\polimesa\\videos\\"+filename) //this is where i want the same variable
.setVideoBitRate(200000)
.done();
log.debug("Creating the executor");
FFmpegExecutor executor = new FFmpegExecutor(ffmpeg, ffprobe);
log.debug("Starting the transcoding");
// Run a one-pass encode
executor.createJob(builder).run();
log.debug("Transcoding finished");
}
}

Can't copy internal file to user's computer

I have a program that requires that an internal file (DICTIONARY) be copied to the user's computer into the folder defined like so:
private static final String DIC_NAME = "WordHelp.dic";
private static final String DIC_FOLDER = System.getProperty("user.home");
private static final String PATH_SEP = System.getProperty("file.separator");
public static final String DICTIONARY = DIC_FOLDER + PATH_SEP + DIC_NAME;
Here's what works on MY computer, where all the Java stuff is:
public static void createDictionaryIfNecessary() throws IOException{
Path out_path = FileSystems.getDefault().getPath(DICTIONARY);
boolean dic_exists = Files.exists(out_path,
new LinkOption[]{LinkOption.NOFOLLOW_LINKS});
if(dic_exists)
return;
File file = new File("src/dictionary"); // here's problem for user ************
Path in_path = file.toPath();
try {
Files.copy(in_path, out_path,
REPLACE_EXISTING, COPY_ATTRIBUTES, NOFOLLOW_LINKS);
} catch (IOException e) { JOptionPane.showMessageDialog(null, e); }
}
But user gets this error:
java.nio.file.NoSuchFileException: src\dictionary
SOURCE file (internal to .jar file) can't be found.
If I look at in_path while debugging, the value is:
(sun.nio.fs.Windowspath) src/dictionary
And below is a bunch of info about in_path:
This all works on MY computer and I could have sworn that it ONCE worked on a user's computer...
How should I define file (see line with ********** to enable copying internal file (src/dictionary) onto a user's computer?
Here's Netbeans project view:

I worked around it by using a Scanner to read individual strings from the internal file instead of using Files.copy. Here's the code. (It's not quite as fast using Scanner, but it works.)
public static void write(FileOutputStream outfile, String s) {
try {
for(int i = 0; i < s.length(); i++)
outfile.write(s.charAt(i));
outfile.write(13); outfile.write(10);
} catch (IOException ex) {JOptionPane.showMessageDialog(null, ex);}
}
public static Scanner openDic(){
InputStream myStream = null;
try { myStream = Class.forName("masterwords.Masterwords").getClassLoader()
.getResourceAsStream("dictionary");
}catch (ClassNotFoundException ex) {/* ... */}
return new Scanner(myStream).useDelimiter("\r");
}
public static void createDictionaryIfNecessary(){
Path out_path = FileSystems.getDefault().getPath(DICTIONARY);
if(Files.exists(out_path, new LinkOption[]{LinkOption.NOFOLLOW_LINKS})) return;
FileOutputStream outStream = null;
try {outStream = new FileOutputStream(out_path.toFile());}
catch (FileNotFoundException ex) {JOptionPane.showMessageDialog(null,ex);}
Scanner scInternalDic = IO.openDic();
while(scInternalDic.hasNext()){
Utilities.write(outStream,scInternalDic.next());
}
try {outStream.close();}
catch (IOException ex) {JOptionPane.showMessageDialog(null,ex);}
scInternalDic.close();
}

How to copy file from one location to another location?

I want to copy a file from one location to another location in Java. What is the best way to do this?
Here is what I have so far:
import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.List;
public class TestArrayList {
public static void main(String[] args) {
File f = new File(
"D:\\CBSE_Demo\\Demo_original\\fscommand\\contentplayer\\config");
List<String>temp=new ArrayList<String>();
temp.add(0, "N33");
temp.add(1, "N1417");
temp.add(2, "N331");
File[] matchingFiles = null;
for(final String temp1: temp){
matchingFiles = f.listFiles(new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.startsWith(temp1);
}
});
System.out.println("size>>--"+matchingFiles.length);
}
}
}
This does not copy the file, what is the best way to do this?

You can use this (or any variant):
Files.copy(src, dst, StandardCopyOption.REPLACE_EXISTING);
Also, I'd recommend using File.separator or / instead of \\ to make it compliant across multiple OS, question/answer on this available here.
Since you're not sure how to temporarily store files, take a look at ArrayList:
List<File> files = new ArrayList();
files.add(foundFile);
To move a List of files into a single directory:
List<File> files = ...;
String path = "C:/destination/";
for(File file : files) {
Files.copy(file.toPath(),
(new File(path + file.getName())).toPath(),
StandardCopyOption.REPLACE_EXISTING);
}

Update:
see also
https://stackoverflow.com/a/67179064/1847899
Using Stream
private static void copyFileUsingStream(File source, File dest) throws IOException {
InputStream is = null;
OutputStream os = null;
try {
is = new FileInputStream(source);
os = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
while ((length = is.read(buffer)) > 0) {
os.write(buffer, 0, length);
}
} finally {
is.close();
os.close();
}
}
Using Channel
private static void copyFileUsingChannel(File source, File dest) throws IOException {
FileChannel sourceChannel = null;
FileChannel destChannel = null;
try {
sourceChannel = new FileInputStream(source).getChannel();
destChannel = new FileOutputStream(dest).getChannel();
destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
}finally{
sourceChannel.close();
destChannel.close();
}
}
Using Apache Commons IO lib:
private static void copyFileUsingApacheCommonsIO(File source, File dest) throws IOException {
FileUtils.copyFile(source, dest);
}
Using Java SE 7 Files class:
private static void copyFileUsingJava7Files(File source, File dest) throws IOException {
Files.copy(source.toPath(), dest.toPath());
}
Or try Googles Guava :
https://github.com/google/guava
docs:
https://guava.dev/releases/snapshot-jre/api/docs/com/google/common/io/Files.html

Use the New Java File classes in Java >=7.
Create the below method and import the necessary libs.
public static void copyFile( File from, File to ) throws IOException {
Files.copy( from.toPath(), to.toPath() );
}
Use the created method as below within main:
File dirFrom = new File(fileFrom);
File dirTo = new File(fileTo);
try {
copyFile(dirFrom, dirTo);
} catch (IOException ex) {
Logger.getLogger(TestJava8.class.getName()).log(Level.SEVERE, null, ex);
}
NB:- fileFrom is the file that you want to copy to a new file fileTo in a different folder.
Credits - #Scott: Standard concise way to copy a file in Java?

public static void copyFile(File oldLocation, File newLocation) throws IOException {
if ( oldLocation.exists( )) {
BufferedInputStream reader = new BufferedInputStream( new FileInputStream(oldLocation) );
BufferedOutputStream writer = new BufferedOutputStream( new FileOutputStream(newLocation, false));
try {
byte[] buff = new byte[8192];
int numChars;
while ( (numChars = reader.read( buff, 0, buff.length ) ) != -1) {
writer.write( buff, 0, numChars );
}
} catch( IOException ex ) {
throw new IOException("IOException when transferring " + oldLocation.getPath() + " to " + newLocation.getPath());
} finally {
try {
if ( reader != null ){
writer.close();
reader.close();
}
} catch( IOException ex ){
Log.e(TAG, "Error closing files when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}
} else {
throw new IOException("Old location does not exist when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}

Copy a file from one location to another location means,need to copy the whole content to another location.Files.copy(Path source, Path target, CopyOption... options) throws IOException this method expects source location which is original file location and target location which is a new folder location with destination same type file(as original).
Either Target location needs to exist in our system otherwise we need to create a folder location and then in that folder location we need to create a file with the same name as original filename.Then using copy function we can easily copy a file from one location to other.
public static void main(String[] args) throws IOException {
String destFolderPath = "D:/TestFile/abc";
String fileName = "pqr.xlsx";
String sourceFilePath= "D:/TestFile/xyz.xlsx";
File f = new File(destFolderPath);
if(f.mkdir()){
System.out.println("Directory created!!!!");
}
else {
System.out.println("Directory Exists!!!!");
}
f= new File(destFolderPath,fileName);
if(f.createNewFile()) {
System.out.println("File Created!!!!");
} else {
System.out.println("File exists!!!!");
}
Files.copy(Paths.get(sourceFilePath), Paths.get(destFolderPath, fileName),REPLACE_EXISTING);
System.out.println("Copy done!!!!!!!!!!!!!!");
}

You can do it with the Java 8 Streaming API, PrintWriter and the Files API
try (PrintWriter pw = new PrintWriter(new File("destination-path"), StandardCharsets.UTF_8)) {
Files.readAllLines(Path.of("src/test/resources/source-file.something"), StandardCharsets.UTF_8)
.forEach(pw::println);
}
If you want to modify the content on-the-fly while copying, check out this link for the extended example https://overflowed.dev/blog/copy-file-and-modify-with-java-streams/

I modified one of the answers to make it a bit more efficient.
public void copy(){
InputStream in = null;
try {
in = new FileInputStream(Files);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
try {
OutputStream out = new FileOutputStream();
try {
// Transfer bytes from in to out
byte[] buf = new byte[1024];
while (true) {
int len = 0;
try {
if (!((len = in.read(buf)) > 0)) break;
} catch (IOException e) {
e.printStackTrace();
}
try {
out.write(buf, 0, len);
} catch (IOException e) {
e.printStackTrace();
}
}
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
} finally {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void moveFile() {
copy();
File dir = getFilesDir();
File file = new File(dir, "my_filename");
boolean deleted = file.delete();
}

Files.exists()
Files.createDirectory()
Files.copy()
Overwriting Existing Files:
Files.move()
Files.delete()
Files.walkFileTree()
enter link description here

You can use
FileUtils.copy(sourceFile, destinationFile);
https://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/FileUtils.html

Extracting .jar files to a directory, adding new files, then repacking into a .jar file in java

I was wondering whether there is a way to take a given .jar file, selected with a JFileChooser, extract it and put it into a new directory. Then, take all the files from another directory, add it to the directory with the extracted .jar file, and then take all that and package it back up again.
I'm doing this because I want a really easy way to install mods for that game, minecraft, where you can just select your minecraft.jar, and make sure the files for the mod are in a folder, and wait a bit, as indicated by a JProgressBar.
This is all I have so far
import java.io.*;
import java.util.jar.*;
import javax.swing.*;
public class Main extends JFrame {
public Main() {
super("Auto-mod installer");
setSize(300, 60);
setLocationRelativeTo(null);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JProgressBar bar = new JProgressBar(0, 100);
add(bar);
setVisible(true);
}
public static void main(String[] args) {
Main m = new Main();
}
private void extract(File f) {
//Hrm...
}
private void addModFiles() {
//Uh...
}
private void repackage(File f) {
//What?
}
}
As you can see, I have no idea what I'm doing. I do know what the imports needed are, but that's about it. Help would be appreciated, ranting about anything I did wrong would get me mad. Thanks!
EDIT: If you know a way to get the same results, and it's not the way that I was looking for, please let me know how to do so. As long as I get the results I was looking for, it would be great. Thanks again!

The idea is relatively simple. You have a few gotchas (like what to do if files already exist and that kind of thing), but otherwise...
I'd start by having a look at JarFile
(I'm in the middle of another example, but when I get time, I'll post some stuff)
UPDATE with Example
public class JarTest {
protected static final String OUTPUT_PATH = "..."; // The place you want to extact the jar to
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
new JarTest();
}
public JarTest() {
try {
unjar();
// Copy new contents in...
jar();
} catch (IOException exp) {
exp.printStackTrace();
}
}
// This just recursivly lists through all the files to be included in the new jar
// We don't care about the directories, as we will create them from the file
// references in the Jar ourselves
protected List<File> getFiles(File path) {
List<File> lstFiles = new ArrayList<File>(25);
// If you want the directories, add the "path" to the list now...
File[] files = path.listFiles();
if (files != null && files.length > 0) {
for (File file : files) {
if (file.isDirectory()) {
lstFiles.addAll(getFiles(file));
} else {
lstFiles.add(file);
}
}
}
return lstFiles;
}
// Re-Jar the contents
// You should always attempt to jar back to a new file, as you may not want to effect the original ;)
public void jar() throws IOException {
JarOutputStream jos = null;
try {
String outputPath = OUTPUT_PATH;
// Create a new JarOutputStream to the file you want to create
jos = new JarOutputStream(new FileOutputStream("...")); // Add your file reference
List<File> fileList = getFiles(new File(OUTPUT_PATH));
System.out.println("Jaring " + fileList.size() + " files");
// Okay, I cheat. I make a list of all the paths already added to the Jar only create
// them when I need to. You could use "file.isDirectory", but that would mean you would need
// to ensure that the files were sorted to allow all the directories to be first
// or make sure that the directory reference is added to the start of each recursion list
List<String> lstPaths = new ArrayList<String>(25);
for (File file : fileList) {
// Replace the Windows file seperator
// We only want the path to this element
String path = file.getParent().replace("\\", "/");
// Get the name of the file
String name = file.getName();
// Remove the output path from the start of the path
path = path.substring(outputPath.length());
// Remove the leading slash if it exists
if (path.startsWith("/")) {
path = path.substring(1);
}
// Add the path path reference to the Jar
// A JarEntry is considered to be a directory if it ends with "/"
if (path.length() > 0) {
// At the trailing path seperator
path += "/";
// Check to see if we've already added it out not
if (!lstPaths.contains(path)) {
// At the path entry...we need need this to make it easier to
// extract the files at a later state. There is a way to cheat,
// but I'll let you figure it out
JarEntry entry = new JarEntry(path);
jos.putNextEntry(entry);
jos.closeEntry();
// Make sure we don't try to add the same path entry again
lstPaths.add(path);
}
}
System.out.println("Adding " + path + name);
// Create the actual entry for this file
JarEntry entry = new JarEntry(path + name);
jos.putNextEntry(entry);
// Write the entry to the file
FileInputStream fis = null;
try {
fis = new FileInputStream(file);
byte[] byteBuffer = new byte[1024];
int bytesRead = -1;
while ((bytesRead = fis.read(byteBuffer)) != -1) {
jos.write(byteBuffer, 0, bytesRead);
}
jos.flush();
} finally {
try {
fis.close();
} catch (Exception e) {
}
}
jos.closeEntry();
}
jos.flush();
} finally {
try {
jos.close();
} catch (Exception e) {
}
}
}
public void unjar() throws IOException {
JarFile jarFile = null;
try {
String outputPath = OUTPUT_PATH;
File outputPathFile = new File(outputPath);
// Make the output directories.
// I'll leave it up to you to decide how best to deal with existing content ;)
outputPathFile.mkdirs();
// Create a new JarFile reference
jarFile = new JarFile(new File("C:/hold/Java_Harmony.jar"));
// Get a list of all the entries
Enumeration<JarEntry> entries = jarFile.entries();
while (entries.hasMoreElements()) {
// Get the next entry
JarEntry entry = entries.nextElement();
// Make a file reference
File path = new File(outputPath + File.separator + entry.getName());
if (entry.isDirectory()) {
// Make the directory structure if we can
if (!path.exists() && !path.mkdirs()) {
throw new IOException("Failed to create output path " + path);
}
} else {
System.out.println("Extracting " + path);
// Extract the file from the Jar and write it to disk
InputStream is = null;
OutputStream os = null;
try {
is = jarFile.getInputStream(entry);
os = new FileOutputStream(path);
byte[] byteBuffer = new byte[1024];
int bytesRead = -1;
while ((bytesRead = is.read(byteBuffer)) != -1) {
os.write(byteBuffer, 0, bytesRead);
}
os.flush();
} finally {
try {
os.close();
} catch (Exception e) {
}
try {
is.close();
} catch (Exception e) {
}
}
}
}
} finally {
try {
jarFile.close();
} catch (Exception e) {
}
}
}
}

You can use this very simple library to pack/unpack jar file
JarManager
Very simple
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import fr.stevecohen.jarmanager.JarPacker;
import fr.stevecohen.jarmanager.JarUnpacker;
public class MyClass {
public void addFileToJar(String jarPath, String otherFilePath) {
try {
JarUnpacker jarUnpacker = new JarUnpacker();
File myJar = new File("./myfile.jar");
File otherFile = new File(otherFilePath);
Path unpackDir = Files.createTempDirectory(myJar.getName()); //create a temp directory to extract your jar
System.out.println("Unpacking in " + unpackDir.toString());
jarUnpacker.unpack(jarPath, unpackDir.toString()); //extraxt all files contained in the jar in temp directory
Files.copy(otherFile.toPath(), new File(unpackDir.toFile(), otherFile.getName()).toPath()); //copy your file
JarPacker jarRepacker = new JarPacker();
File newJar = new File("./maNewFile.jar");
System.out.println("Packing jar in " + newJar.getAbsolutePath());
jarRepacker.pack(unpackDir.toString(), newJar.getAbsolutePath()); //repack the jar with the new files inside
} catch (IOException e) {
e.printStackTrace();
}
}
}
You can also use maven dependency
<dependency>
<groupId>fr.stevecohen.jarmanager</groupId>
<artifactId>JarManager</artifactId>
<version>0.5.0</version>
</dependency>
You also need my repository
<repository>
<id>repo-reapersoon</id>
<name>ReaperSoon's repo</name>
<url>http://repo-maven.stevecohen.fr</url>
</repository>
Check the last version with the link bellow to use the last dependency
Please use my public issue tracker if you find some bugs

Combining audio files

I recorded some audio files, stored them in sdcard. I need to combine all the recorded files into a single audiofile. I used the following code. My problem is the combined file contains only the first recorded file. Any suggestions...In readAudioAsStream() method i tried to combine the files.
public void readAudioAsStream() {
getFullAudioPath()
File f;
FileInputStream ins = null;
try
{
String comfile=getCombineFile();
//FileOutputStream fos=new FileOutputStream(comfile);
Log.d("combined file",comfile);
File file=new File(comfile);
RandomAccessFile raf = new RandomAccessFile(file, "rw");
Log.d("path size",Integer.toString(audFullPath.size()));
for (int i=0;i<audFullPath.size();i++)
{
String filepath=audFullPath.get(i);
Log.d("Filepath",filepath);
f=new File(audFullPath.get(i));
fileContent = new byte[(int)f.length()];
ins=new FileInputStream(audFullPath.get(i));
int numofbytes=ins.read(fileContent);
System.out.println("Number Of Bytes Read===========>>>"+numofbytes);
raf.seek(file.length());
raf.write(fileContent);
}
}
catch (FileNotFoundException e1) {
e1.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
}
public ArrayList<String> getFullAudioPath() {
ArrayList<String> fullPath=new ArrayList<String>();
fullPath.clear();
String path=filePath();
File f=new File(path);
if(f.isDirectory())
{
File[] files=f.listFiles();
for(int i=0;i<files.length;i++)
{
String fpath=path+File.separator+files[i].getName().toString().trim();
System.out.println("File Full Path======>>>"+fpath);
fullPath.add(fpath);
}
}
return fullPath;
}
public String filePath() {
String newFolderName="/MyAudio";
String extstoredir=Environment.getExternalStorageDirectory().toString();
String newPath=extstoredir+newFolderName;
return newPath;
}
public String getCombineFile() {
String newFolderName="/MyComAudio";
String extstoredir=Environment.getExternalStorageDirectory().toString();
String path=extstoredir+newFolderName;
File myNewPath=new File(path);
if(!myNewPath.exists()) {
myNewPath.mkdir();
}
String audname="ComAudio";
String ext=".3gp";
File audio=new File(myNewPath,audname+ext);
if(audio.exists()) {
audio.delete();
}
String audpath=path+"/"+audname+ext;
Log.d("Combined audio file",audpath);
return audpath;
}

You can't merge two .3gp files just by writing content of one .3gp file at the end of another .3gp file.