Как изменить директорию java

There is no reliable way to do this in pure Java. Setting the user.dir property via System.setProperty() or java -Duser.dir=... does seem to affect subsequent creations of Files, but not e.g. FileOutputStreams.

The File(String parent, String child) constructor can help if you build up your directory path separately from your file path, allowing easier swapping.

An alternative is to set up a script to run Java from a different directory, or use JNI native code as suggested below.

The relevant OpenJDK bug was closed in 2008 as «will not fix».

answered May 8, 2009 at 15:04

There is a way to do this using the system property «user.dir». The key part to understand is that getAbsoluteFile() must be called (as shown below) or else relative paths will be resolved against the default «user.dir» value.

import java.io.*;

public class FileUtils
{
    public static boolean setCurrentDirectory(String directory_name)
    {
        boolean result = false;  // Boolean indicating whether directory was set
        File    directory;       // Desired current working directory

        directory = new File(directory_name).getAbsoluteFile();
        if (directory.exists() || directory.mkdirs())
        {
            result = (System.setProperty("user.dir", directory.getAbsolutePath()) != null);
        }

        return result;
    }

    public static PrintWriter openOutputFile(String file_name)
    {
        PrintWriter output = null;  // File to open for writing

        try
        {
            output = new PrintWriter(new File(file_name).getAbsoluteFile());
        }
        catch (Exception exception) {}

        return output;
    }

    public static void main(String[] args) throws Exception
    {
        FileUtils.openOutputFile("DefaultDirectoryFile.txt");
        FileUtils.setCurrentDirectory("NewCurrentDirectory");
        FileUtils.openOutputFile("CurrentDirectoryFile.txt");
    }
}

answered Dec 20, 2012 at 23:00

As mentioned you can’t change the CWD of the JVM but if you were to launch another process using Runtime.exec() you can use the overloaded method that lets you specify the working directory. This is not really for running your Java program in another directory but for many cases when one needs to launch another program like a Perl script for example, you can specify the working directory of that script while leaving the working dir of the JVM unchanged.

See Runtime.exec javadocs

Specifically,

public Process exec(String[] cmdarray,String[] envp, File dir) throws IOException

where dir is the working directory to run the subprocess in

answered Feb 6, 2013 at 15:20

answered May 8, 2009 at 14:58

The working directory is a operating system feature (set when the process starts).
Why don’t you just pass your own System property (-Dsomeprop=/my/path) and use that in your code as the parent of your File:

File f = new File ( System.getProperty("someprop"), myFilename)

answered May 8, 2009 at 14:59

matt bmatt b

137k65 gold badges281 silver badges343 bronze badges

I have tried to invoke

String oldDir = System.setProperty("user.dir", currdir.getAbsolutePath());

It seems to work. But

File myFile = new File("localpath.ext");
InputStream openit = new FileInputStream(myFile);

throws a FileNotFoundException though

myFile.getAbsolutePath()

shows the correct path.
I have read this. I think the problem is:

• Java knows the current directory with the new setting.
• But the file handling is done by the operation system. It does not know the new set current directory, unfortunately.

The solution may be:

File myFile = new File(System.getPropety("user.dir"), "localpath.ext");

It creates a file Object as absolute one with the current directory which is known by the JVM. But that code should be existing in a used class, it needs changing of reused codes.

~~~~JcHartmut

You can use

new File(«relative/path»).getAbsoluteFile()

after

System.setProperty(«user.dir», «/some/directory»)

System.setProperty("user.dir", "C:/OtherProject");
File file = new File("data/data.csv").getAbsoluteFile();
System.out.println(file.getPath());

Will print

C:OtherProjectdatadata.csv

answered Jun 10, 2017 at 7:37

Andy ThomasAndy Thomas

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Nathan FegerNathan Feger

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lesolorzanovlesolorzanov

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Use FileSystemView

private FileSystemView fileSystemView;
fileSystemView = FileSystemView.getFileSystemView();
currentDirectory = new File(".");
//listing currentDirectory
File[] filesAndDirs = fileSystemView.getFiles(currentDirectory, false);
fileList = new ArrayList<File>();
dirList = new ArrayList<File>();
for (File file : filesAndDirs) {
if (file.isDirectory())
    dirList.add(file);
else
    fileList.add(file);
}
Collections.sort(dirList);
if (!fileSystemView.isFileSystemRoot(currentDirectory))
    dirList.add(0, new File(".."));
Collections.sort(fileList);
//change
currentDirectory = fileSystemView.getParentDirectory(currentDirectory);

answered Sep 11, 2013 at 14:23

There is no reliable way to do this in pure Java. Setting the user.dir property via System.setProperty() or java -Duser.dir=... does seem to affect subsequent creations of Files, but not e.g. FileOutputStreams.

The File(String parent, String child) constructor can help if you build up your directory path separately from your file path, allowing easier swapping.

An alternative is to set up a script to run Java from a different directory, or use JNI native code as suggested below.

The relevant OpenJDK bug was closed in 2008 as «will not fix».

answered May 8, 2009 at 15:04

There is a way to do this using the system property «user.dir». The key part to understand is that getAbsoluteFile() must be called (as shown below) or else relative paths will be resolved against the default «user.dir» value.

import java.io.*;

public class FileUtils
{
    public static boolean setCurrentDirectory(String directory_name)
    {
        boolean result = false;  // Boolean indicating whether directory was set
        File    directory;       // Desired current working directory

        directory = new File(directory_name).getAbsoluteFile();
        if (directory.exists() || directory.mkdirs())
        {
            result = (System.setProperty("user.dir", directory.getAbsolutePath()) != null);
        }

        return result;
    }

    public static PrintWriter openOutputFile(String file_name)
    {
        PrintWriter output = null;  // File to open for writing

        try
        {
            output = new PrintWriter(new File(file_name).getAbsoluteFile());
        }
        catch (Exception exception) {}

        return output;
    }

    public static void main(String[] args) throws Exception
    {
        FileUtils.openOutputFile("DefaultDirectoryFile.txt");
        FileUtils.setCurrentDirectory("NewCurrentDirectory");
        FileUtils.openOutputFile("CurrentDirectoryFile.txt");
    }
}

answered Dec 20, 2012 at 23:00

As mentioned you can’t change the CWD of the JVM but if you were to launch another process using Runtime.exec() you can use the overloaded method that lets you specify the working directory. This is not really for running your Java program in another directory but for many cases when one needs to launch another program like a Perl script for example, you can specify the working directory of that script while leaving the working dir of the JVM unchanged.

See Runtime.exec javadocs

Specifically,

public Process exec(String[] cmdarray,String[] envp, File dir) throws IOException

where dir is the working directory to run the subprocess in

answered Feb 6, 2013 at 15:20

answered May 8, 2009 at 14:58

The working directory is a operating system feature (set when the process starts).
Why don’t you just pass your own System property (-Dsomeprop=/my/path) and use that in your code as the parent of your File:

File f = new File ( System.getProperty("someprop"), myFilename)

answered May 8, 2009 at 14:59

matt bmatt b

137k65 gold badges281 silver badges343 bronze badges

I have tried to invoke

String oldDir = System.setProperty("user.dir", currdir.getAbsolutePath());

It seems to work. But

File myFile = new File("localpath.ext");
InputStream openit = new FileInputStream(myFile);

throws a FileNotFoundException though

myFile.getAbsolutePath()

shows the correct path.
I have read this. I think the problem is:

• Java knows the current directory with the new setting.
• But the file handling is done by the operation system. It does not know the new set current directory, unfortunately.

The solution may be:

File myFile = new File(System.getPropety("user.dir"), "localpath.ext");

It creates a file Object as absolute one with the current directory which is known by the JVM. But that code should be existing in a used class, it needs changing of reused codes.

~~~~JcHartmut

You can use

new File(«relative/path»).getAbsoluteFile()

after

System.setProperty(«user.dir», «/some/directory»)

System.setProperty("user.dir", "C:/OtherProject");
File file = new File("data/data.csv").getAbsoluteFile();
System.out.println(file.getPath());

Will print

C:OtherProjectdatadata.csv

answered Jun 10, 2017 at 7:37

Andy ThomasAndy Thomas

83.9k11 gold badges103 silver badges148 bronze badges

Nathan FegerNathan Feger

18.9k11 gold badges61 silver badges70 bronze badges

lesolorzanovlesolorzanov

3,4857 gold badges34 silver badges53 bronze badges

Use FileSystemView

private FileSystemView fileSystemView;
fileSystemView = FileSystemView.getFileSystemView();
currentDirectory = new File(".");
//listing currentDirectory
File[] filesAndDirs = fileSystemView.getFiles(currentDirectory, false);
fileList = new ArrayList<File>();
dirList = new ArrayList<File>();
for (File file : filesAndDirs) {
if (file.isDirectory())
    dirList.add(file);
else
    fileList.add(file);
}
Collections.sort(dirList);
if (!fileSystemView.isFileSystemRoot(currentDirectory))
    dirList.add(0, new File(".."));
Collections.sort(fileList);
//change
currentDirectory = fileSystemView.getParentDirectory(currentDirectory);

answered Sep 11, 2013 at 14:23

There is no reliable way to do this in pure Java. Setting the user.dir property via System.setProperty() or java -Duser.dir=... does seem to affect subsequent creations of Files, but not e.g. FileOutputStreams.

The File(String parent, String child) constructor can help if you build up your directory path separately from your file path, allowing easier swapping.

An alternative is to set up a script to run Java from a different directory, or use JNI native code as suggested below.

The relevant OpenJDK bug was closed in 2008 as «will not fix».

answered May 8, 2009 at 15:04

There is a way to do this using the system property «user.dir». The key part to understand is that getAbsoluteFile() must be called (as shown below) or else relative paths will be resolved against the default «user.dir» value.

import java.io.*;

public class FileUtils
{
    public static boolean setCurrentDirectory(String directory_name)
    {
        boolean result = false;  // Boolean indicating whether directory was set
        File    directory;       // Desired current working directory

        directory = new File(directory_name).getAbsoluteFile();
        if (directory.exists() || directory.mkdirs())
        {
            result = (System.setProperty("user.dir", directory.getAbsolutePath()) != null);
        }

        return result;
    }

    public static PrintWriter openOutputFile(String file_name)
    {
        PrintWriter output = null;  // File to open for writing

        try
        {
            output = new PrintWriter(new File(file_name).getAbsoluteFile());
        }
        catch (Exception exception) {}

        return output;
    }

    public static void main(String[] args) throws Exception
    {
        FileUtils.openOutputFile("DefaultDirectoryFile.txt");
        FileUtils.setCurrentDirectory("NewCurrentDirectory");
        FileUtils.openOutputFile("CurrentDirectoryFile.txt");
    }
}

answered Dec 20, 2012 at 23:00

As mentioned you can’t change the CWD of the JVM but if you were to launch another process using Runtime.exec() you can use the overloaded method that lets you specify the working directory. This is not really for running your Java program in another directory but for many cases when one needs to launch another program like a Perl script for example, you can specify the working directory of that script while leaving the working dir of the JVM unchanged.

See Runtime.exec javadocs

Specifically,

public Process exec(String[] cmdarray,String[] envp, File dir) throws IOException

where dir is the working directory to run the subprocess in

answered Feb 6, 2013 at 15:20

answered May 8, 2009 at 14:58

The working directory is a operating system feature (set when the process starts).
Why don’t you just pass your own System property (-Dsomeprop=/my/path) and use that in your code as the parent of your File:

File f = new File ( System.getProperty("someprop"), myFilename)

answered May 8, 2009 at 14:59

matt bmatt b

137k65 gold badges281 silver badges343 bronze badges

I have tried to invoke

String oldDir = System.setProperty("user.dir", currdir.getAbsolutePath());

It seems to work. But

File myFile = new File("localpath.ext");
InputStream openit = new FileInputStream(myFile);

throws a FileNotFoundException though

myFile.getAbsolutePath()

shows the correct path.
I have read this. I think the problem is:

• Java knows the current directory with the new setting.
• But the file handling is done by the operation system. It does not know the new set current directory, unfortunately.

The solution may be:

File myFile = new File(System.getPropety("user.dir"), "localpath.ext");

It creates a file Object as absolute one with the current directory which is known by the JVM. But that code should be existing in a used class, it needs changing of reused codes.

~~~~JcHartmut

You can use

new File(«relative/path»).getAbsoluteFile()

after

System.setProperty(«user.dir», «/some/directory»)

System.setProperty("user.dir", "C:/OtherProject");
File file = new File("data/data.csv").getAbsoluteFile();
System.out.println(file.getPath());

Will print

C:OtherProjectdatadata.csv

answered Jun 10, 2017 at 7:37

Andy ThomasAndy Thomas

83.9k11 gold badges103 silver badges148 bronze badges

Nathan FegerNathan Feger

18.9k11 gold badges61 silver badges70 bronze badges

lesolorzanovlesolorzanov

3,4857 gold badges34 silver badges53 bronze badges

Use FileSystemView

private FileSystemView fileSystemView;
fileSystemView = FileSystemView.getFileSystemView();
currentDirectory = new File(".");
//listing currentDirectory
File[] filesAndDirs = fileSystemView.getFiles(currentDirectory, false);
fileList = new ArrayList<File>();
dirList = new ArrayList<File>();
for (File file : filesAndDirs) {
if (file.isDirectory())
    dirList.add(file);
else
    fileList.add(file);
}
Collections.sort(dirList);
if (!fileSystemView.isFileSystemRoot(currentDirectory))
    dirList.add(0, new File(".."));
Collections.sort(fileList);
//change
currentDirectory = fileSystemView.getParentDirectory(currentDirectory);

answered Sep 11, 2013 at 14:23