Develop Reference

Unlock a file opened by Excel, Word, or any program

The code I'm writing in Java is is close a file left open by the user. So, here is what typically happens: a user is editing an Excel file, they save it, leave it open, and then close the lid on their laptop. The file is still kept open and locked so no one else can edit it. Is there a way to kick them off and unlock the file? When they are using the file, it is "checked out." Here is what shows up:
What checked out looks like: (image)
The following code, interfacing through WinDAV with SharePoint, tells me if a file is locked or not (I know it's not great code, but it works and I've tried several other solutions including Filelock, Apache IO, FileStream, etc.):
String fileName = String.valueOf(node);
File file = new File(fileName);
boolean replaced;
File sameFileName = new File(fileName);
if(file.renameTo(new File(sameFileName + "_UNLOCK"))){
replaced = true; //file is currently not in use
(new File(sameFileName + "_UNLOCK")).renameTo(sameFileName);
}else{
replaced = false; //file is currently in use
}
So, how would I unlock a file now? The only other solution is PowerShell using SharePoint libraries, but that has a whole lot of other problems...

As per the post, you can use the tool Handle, which is a CLI tool to find out which process is locking the file. Once you have the process ID, you can kill that process. I'm not aware of any Java API that would identify the culprit process. For killing the process you can use taskkill, and you can call it using Runtime like this. Both the operation require you app to run at Administrator or above privilege.

java open csv file using excel

I am making a project for college and have made a program which creates csv files. I would like there to be a button which you can click which then opens the csv file with excel. Thanks

Knowing that MsOffice is installed on the system, you should be able to open a document with it from command line using the command
excel myDoc.csv
to execute such a command from java, you could use this snapshot:
File myCSVFile; //reference to your file here
String execString = "excel " + myCSVFile.getAbsolutePath();
Runtime run = Runtime.getRuntime();
try {
Process pp = run.exec(execString);
} catch(Exception e) {
e.printStackTrace();
}
This is somewhat rough and needs styling, of course, but generally it should work. Besides, to be more graceful you could also check Windows registry, using the java.util.prefs.Preferences class, to know if MsOffice is installed and, if yes, where. But, please, be aware, if you are reckoning for MsExcel (as I understood from your post), this will automatically cancel Java's multiplatform approach. Hopefully, this helps :)

If you are using Java 6 you can use the Desktop class. Read also Opening, Editing, and Printing a File

You can use JExcel API. It will be very easy for you.

For whatever reason, execString's provided did not work for me, but the one below worked:
String execString = "cmd /c start excel \"" + filePathString + "\"";
With the other exeString's I kept getting an exception saying that the runtime cannot find the file - start or excel.

How to open the notepad file in java?

I want to open Notepad in my Java program. Suppose that I have one button if I click this button the notepad will appear.
I already have a file name and a directory.
How can I implement this case?

Try
if (Desktop.isDesktopSupported()) {
Desktop.getDesktop().edit(file);
} else {
// I don't know, up to you to handle this
}
Make sure the file exists. Thanks to Andreas_D who pointed this out.

(assuming you want notepad to open "myfile.txt" :)
ProcessBuilder pb = new ProcessBuilder("Notepad.exe", "myfile.txt");
pb.start();

Assuming you wish to launch the windows program notepad.exe, you are looking for the exec function. You probably want to call something like:
Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec("C:\\path\\to\\notepad.exe C:\\path\\to\\file.txt");
For example, on my machine notepad is located at C:\Windows\notepad.exe:
Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec("C:\\Windows\\notepad.exe C:\\test.txt");
This will open notepad with the file test.txt open for editing.
Note you can also specify a third parameter to exec which is the working directory to execute from - therefore, you could launch a text file that is stored relative to the working directory of your program.

Using SWT, you can launch any
If you want to emulate double-clicking on a text in windows, it's not possible only with a plain JRE. You can use a native library like SWT and use the following code to open a file:
org.eclipse.swt.program.Program.launch("c:\path\to\file.txt")
If you don't want to use a third-party lib, you should know and you know where notepad.exe is (or it's visible in PATH):
runtime.exec("notepad.exe c:\path\to\file.txt");
Apache common-exec is a good library for handling external process execution.
UPDATE: A more complete answer to your question can be found here

In IDE (Eclipse) it compains about "C:\path\to\notepad.exe C:\path\to\file.txt" .
So i have used the following which works for me keeping me and my IDE happy :o)
Hopefully this will help others out there.
String fpath;
fPath =System.getProperty("java.io.tmpdir")+"filename1" +getDateTime()+".txt";
//SA - Below launches the generated file, via explorer then delete the file "fPath"
try {
Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec("explorer " + fPath);
Thread.sleep(500); //lets give the OS some time to open the file before deleting
boolean success = (new File(fPath)).delete();
if (!success) {
System.out.println("failed to delete file :"+fPath);
// Deletion failed
}
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

String fileName = "C:\\Users\\Riyasam\\Documents\\NetBeansProjects\\Student Project\\src\\studentproject\\resources\\RealWorld.chm";
String[] commands = {"cmd", "/c", fileName};
try {
Runtime.getRuntime().exec(commands);
//Runtime.getRuntime().exec("C:\\Users\\Riyasam\\Documents\\NetBeansProjects\\SwingTest\\src\\Test\\RealWorld.chm");
} catch (Exception ex) {
ex.printStackTrace();
}

You could do this the best if you start notepad in command line with command: start notepad
String[] startNotePadWithoutAdminPermissions = new String[] {"CMD.EXE", "/C", "start" "notepad" };
Save array of string commands and give it like parametr in exec
Process runtimeProcess = Runtime.getRuntime().exec(startNotepadAdmin2);
runtimeProcess.waitFor();

How can I excute Notepad by Java code

I want to open Notepad program in MS Windows by Java code to open my text file.
Pls help me to do that.

You can use the java.awt.Desktop if using Java 1.6, .txt is registered to the notepad and Desktop is supported:
if (!Desktop.isDesktopSupported()) {
System.err.println("Desktop not supported");
// use alternative (Runtime.exec)
return;
}
Desktop desktop = Desktop.getDesktop();
if (!desktop.isSupported(Desktop.Action.EDIT)) {
System.err.println("EDIT not supported");
// use alternative (Runtime.exec)
return;
}
try {
desktop.edit(new File("test.txt"));
} catch (IOException ex) {
ex.printStackTrace();
}
this way you can open/edit files in a more OS independent way.

Runtime.getRuntime().exec("notepad c:/asd.txt");
where c:/asd.txt is the full path to your text file. If / doesn't work for you, use \\ instead.

If you have registered the .txt extension on your OS and your text file already exists then you can do even
Runtime.getRuntime().exec(new String[]{"cmd.exe","/c","text.txt"});
The advantage is it will take the program associated with .txt, what could be diferent from notepad.exe.

use the ProcessBuilder Class
Process p = new ProcessBuilder("notepad", "file.txt").start();

Opening an Excel file using the default program

My program successfully creates and fills a Excel(.xls) file. Once created, I would like the new file to open in the system's default program (Excel in my case). How can I achieve this?
For an older program where I wanted to open a txt file in Notepad, I used the following:
if (!Desktop.isDesktopSupported()) {
System.err.println("Desktop not supported");
// use alternative (Runtime.exec)
return;
}
Desktop desktop = Desktop.getDesktop();
if (!desktop.isSupported(Desktop.Action.EDIT)) {
System.err.println("EDIT not supported");
// use alternative (Runtime.exec)
return;
}
try {
desktop.edit(new File(this.outputFilePath));
} catch (IOException ex) {
ex.printStackTrace();
}
When I try to use this code for an Excel file it gives me the following error:
java.io.IOException: Failed to edit file:C:/foo.xls
Suggestions?

Try to use Desktop.open() instead of Desktop.edit() :
Desktop dt = Desktop.getDesktop();
dt.open(new File(this.outputFilePath));
If Desktop.open() is not available then the Windows file association can be used :
Process p =
Runtime.getRuntime()
.exec("rundll32 url.dll,FileProtocolHandler " + this.outputFilePath);

You probably did the Runtime.exec incorrectly. Give this a look to see if that's the case.
If you just want to open an Excel file with Java, I'd recommend using Andy Khan's JExcel API. Perhaps using that with a Swing JTable will be just the ticket.

The most simple and efficient way.
Desktop.getDesktop().open(new File("inputFilePath"));