I have a java class file with a main method. In Windows, I would like to be able to drag files onto a desktop icon/short/etc that would call supply the filenames to my main method. Basically, I want to allow users to drag-and-drop files at program execution instead of having type them on the command line.
Any thoughts?
To build on daub815's answer, in Windows, you can use a batch file to pass
arguments to another command. In this case, we'll use the java launcher to
launch your class with the main method.
I did a quick Google search on how to do write a batch file to take multiple arguments,
and found a page with a batch file to pass arguments to another command. Adapting from
the example, here is what you can do:
#ECHO OFF
:Loop
IF "%1" == "" GOTO Done
java YourClass %1
SHIFT
GOTO Loop
:Done
Save the above file as a batch file (with a ".bat" extension), and then you can drag-and-drop
files onto it, and it will be passed as arguments.
Also, you can call the batch file from the command line and pass arguments as well.
Edit: It appears that the batch file will not work with quoted arguments which contain spaces. Using a workaround presented in the site I've linked to will split the spaces contained in the quoted full path of the file into separate arguments, so that won't work either. If anyone has a good idea how to fix this, please either edit this entry, or post another answer. I will make this a community wiki.
PhiLho's answer works perfectly if you pack the classes in an executable JAR file (it's how you're meant to do it anyway) and make a .reg file that looks like the one below. Then just double-click that .reg file to merge it into the registry and you're good to go. This lets you both double-click a JAR file to run it, and starting it by Drag & Drop.
Do remember to change the path to where your Java executable is installed.
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\.jar]
#="jarfile"
[HKEY_CLASSES_ROOT\jarfile\DefaultIcon]
#="C:\\Java\\jdk1.7.0\\bin\\java.exe,1"
[HKEY_CLASSES_ROOT\jarfile\shell\open]
#="Run Java Program"
[HKEY_CLASSES_ROOT\jarfile\shell\open\command]
#="\"C:\\Java\\jdk1.7.0\\bin\\java.exe\" -jar \"%1\" %*"
[HKEY_CLASSES_ROOT\jarfile\shellex\DropHandler]
#="{86C86720-42A0-1069-A2E8-08002B30309D}"
OK, I made it work... The base knowledge is to use DropHandler UUID in the registry. I made a base setting, as follow:
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\.class]
#="JavaClass"
[HKEY_CLASSES_ROOT\JavaClass\DefaultIcon]
#="C:\\Java\\jdk1.6.0_05\\bin\\java.exe,1"
[HKEY_CLASSES_ROOT\JavaClass\shell\open]
#="Run Java class"
[HKEY_CLASSES_ROOT\JavaClass\shell\open\command]
#="\"C:\\Java\\jdk1.6.0_05\\bin\\java.exe\" \"%1\" %*"
[HKEY_CLASSES_ROOT\JavaClass\shellex\DropHandler]
#="{86C86720-42A0-1069-A2E8-08002B30309D}"
and... it didn't work!
I just forgot that java.exe wants a class name, not a file name! But I see no way to do that in the registry.
Fortunately, there is a workaround, which still need a script file if we want to be generic, to work on any/all class files (with static main function, of course!). Not batch, I avoid them when I can. I chose to use WSH, as it should be available on any modern Windows system. I also chose to make a JS script, it could have been a VB script as well.
So I made the following script (LaunchJavaClass.js):
if (WScript.Arguments.count() == 0)
{
WScript.StdOut.Write("No parameters");
WScript.Quit(1);
}
var className = WScript.Arguments.Item(0);
//~ WScript.StdOut.Write(className + "\n");
var m = className.match(/^(.*)\\(.+?)\.class$/);
if (m == null)
{
WScript.StdOut.Write("Not a class file");
WScript.Quit(1);
}
var classPath = m[1];
className = m[2];
//~ WScript.StdOut.Write(classPath + " >>> " + className + "\n");
var params = new Array();
for (i = 1; i < WScript.Arguments.count(); i++)
{
params[params.length] = WScript.Arguments.Item(i);
}
var cmd = "cmd /c cd /D " + classPath +
" & C:/Java/jdk1.6.0_05/bin/java.exe " +
className + " " + params.join(" ");
//~ WScript.StdOut.Write(cmd + "\n");
var shell = WScript.CreateObject("WScript.Shell");
//~ var exec = shell.Exec(cmd); // Can be used to get stdout
shell.Run(cmd, 0);
I left some output, not useful in this context, but usable for debugging (run with cscript).
Of course, the path to the JRE must be adjusted.
And I changed the command in the registry, as follow:
[HKEY_CLASSES_ROOT\JavaClass\shell\open\command]
#="\wscript -b "D:\\_PhiLhoSoft\\WSH\\LaunchJavaClass.js\" %1 %*"
Of course, adjust path, and keep the above other lines.
Now, if I drag'n'drop some files to a .class file, it gets the short file paths as arguments of the main() function.
import java.io.*;
class TestDnD
{
public static void main(String[] args)
{
Writer output = null;
try
{
output = new BufferedWriter(new FileWriter(new File("LogFile.txt")));
for (String arg : args)
{
output.write(arg + "\n");
}
}
catch (IOException ioe)
{
ioe.printStackTrace();
return;
}
finally
{
try { output.close(); } catch (IOException e) {}
}
}
}
I think the first version of the .reg file can be used for something else, eg. to drag'n'drop on .jar files (adapting it, of course).
This technique has limited use: we rarely make one-class programs in Java! But it looked like a good and interesting challenge, so I didn't resist to solve it. Note: you can add stuff like -Djava.ext.dirs="some path;another path" if you ever need to use external libraries (in jar files).
Adding onto Adiel A. If you create a batch file, which launches your a Java window using Swing. You would have the user drop the files onto that window. You could then be able to root through those dropped files.
So there's no way to have windows itself pass the args into main() via drag and drop?
Related
My app launches and loads the file if I do: myApp /file:c:\nospaces.asd from cmd but if I do myApp /file:c:\with spaces.asd it won't work because the program receives two arguments: myApp /file:c:\with and spaces.asd.
I know that I can do myApp "/file:c:\with spaces.asd" and it'll work like that from cmd. However this isn't a good solution because if I double click the .asd file (custom extension) (and select launch with my app) then main won't be getting the arguments as one line but as two arguments.
How can I go about fixing this issue so that my main will receive only one argument when double clicking the file?
You could join the arguments together if the file is not found. Something like this:
public static void main(String[] args) {
String fileName = joinArgumentsToValidFileName(args);
}
public static String joinArgumentsToValidFileName(String[] args) {
if(args.length == 0) {
return "";
}
String fileName = args[0];
int index = 1;
while(!new File(fileName).exists() && index < args.length) {
fileName += " " + args[index];
index++;
}
return fileName;
}
This assumes that the first argument (or the arguments) must be the file name. Any additional agruments could be evaluated by remembering the offset index somehow (not included in the code above).
But note: This is a not standard behavior of passing arguments to an application and could lead to cunfusion. So if you find a way to pass a "" wrapped file name argument, don't do this!
Double clicking to launch java would be affected by whats registered in windows related to the same i.e windows registry for jar-file launch command.
These are some similar questions asked on SO you can take a look at:
Running JAR file on Windows
java can run jar from cmd but not by double clicking
They mention the useful part which is ensuring you have the wildcard behind the executable in the registry c:\...\javaw.exe" -jar "%1" %
I have an executable Jar file and to keep it simple, I want to make it so that you can simply double click it on the desktop and it will run. I've tried this:
if(args.length == 0){
String path = Main.class.getProtectionDomain().getCodeSource().getLocation().getPath();
String decodedPath = URLDecoder.decode(path, "UTF-8");
Runtime rt = Runtime.getRuntime();
Process pr = rt.exec("java -jar \"" + decodedPath + "\" -arg");
System.out.println("java -jar \"" + decodedPath + "\" -arg");
}
To no avail. I assumed that if I told the program to check for the "-arg" argument and it wasn't there, then it would asssume the program was run from the executable, not being called from the command line. So is there a way to make the program open a command prompt and then run itself within it, killing the previous program?
As to "run on double click", this is OS dependent.
You can "run a jar" at the command line using:
java -jar the.jar
This requires that the jar has a META-INF/MANIFEST.MF and that this manifest file has a Main-Class entry, the argument being the class where your main() method is. For instance:
Main-Class: org.foobar.mypackage.Foo
What I have done for a similar problem is that I have made a separate GUI program in a JAR file with some JTextFields for input and a JButton for confirmation. When the button gets clicked, it calls the main method in my other class with those values in a String array to start that program and close the GUI form with frame.setVisible(false). I suggest doing something like that, but it's dependent on what type of program you're developing.
You could also just pass the necessary command-line flags directly into the JRE at runtime! I just figured this out a couple weeks ago, but you can access the java.library.path and change it to match necessary library paths through reflection by just putting this code in the front of your main method.
try{
System.setProperty("java.library.path", path);
Field fieldSysPath = ClassLoader.class.getDeclaredField( "sys_paths" );
fieldSysPath.setAccessible( true );
fieldSysPath.set( null, null );
}catch(Exception ex){
// just exit and tell user that there was an error or something similar
}
Anyway, I hope that this was helpful. You can also do many similar things by similar code.
I've created a GUI (swing) that executes a batch file that contains a command prompt .exe file execution with specific parameters.
When I run the batch file manually (by double clicking it), everything is as expected.
The problem is: the command prompt window doesn't open to show progress, moreover, it doesn't really start to work (only initiated) until I exit the GUI (forking?). When it starts to work, is works somewhere in the background and seen only in the task manager.
Only a blank command prompt window is opened.
From digging little bit around, I've constructed this command that gives me same result as above:
Runtime.getRuntime().exec("cmd.exe /c start \"Encoding\" cmd.exe /c start md \"" + Gui.outputDirField.getText() + "\\encoderOutput\" & cd \"" + Gui.outputDirField.getText() + "\\encoderOutput\" & \"" + Gui._batFile + "\" & pause");
Could you please assist?
Sorry if it sounds stupid..
this way works for me:
new Thread() {
#Override public void run() {
try {
Runtime.getRuntime().exec("cmd.exe /c start " + Gui._batFile);
} catch (IOException e1) {
e1.printStackTrace();
}
}
}.run();
trashgod may be on to something. We ran into issues with paths with spaces. This is from the release notes for jre 7u21
Changes to Runtime.exec
On Windows platform, the decoding of command strings specified to Runtime.exec(String), Runtime.exec(String,String[]) and Runtime.exec(String,String[],File) methods, has been improved to follow the specification more closely. This may cause problems for applications that are using one or more of these methods with commands that contain spaces in the program name, or are invoking these methods with commands that are not quoted correctly.
For example, Runtime.getRuntime().exec("C:\\My Programs\\foo.exe bar") is an attempt to launch the program "C:\\My" with the arguments "Programs\\foo.exe" and "bar". This command is likely to fail with an exception to indicate "C:\My" cannot be found.
The example Runtime.getRuntime().exec("\"C:\\My Programs\\foo.exe\" bar") is an attempt to launch the program "\"C:\\My". This command will fail with an exception to indicate the program has an embedded quote.
Applications that need to launch programs with spaces in the program name should consider using the variants of Runtime.exec that allow the command and arguments to be specified in an array.
Alternatively, the preferred way to create operating systems processes since JDK 5.0 is using java.lang.ProcessBuilder. The ProcessBuilder class has a much more complete API for setting the environment, working directory and redirecting streams for the process.
Does your bat file requiere user interaction or why are you putting a pause on your command? If so, the Runtime.exec just runs the file with no window, why would you want a Window? >ou can get a Process object as a result from the exec, from this object you can get an InputStream (and if needed, an OutputStream) so you can print your output or interact with the process.
This is my first question on stackoverflow so I'll try to keep it concise and relevant.
I'm currently creating a Java program that is attempting to call an external program located on the system, in order to do this however I am required to call a shell script that sets up links to the relevant libraries to ensure that the system is linked to these before the external program can be executed.
The issue at hand is that I cannot invoke the shell script through Java, I've researched high and low and am aware that of alternative ways such as the use of the ProcessBuilder class. Unfortunately I'm quite new to the world of trying to invoke command line statements through Java and so I'm stuck for answers.
An example of the code I am using can be found below:
private void analyse_JButtonActionPerformed(java.awt.event.ActionEvent evt) {
// Get project path for copying of Fortran program to folder and execution
String projectPath = Newproject_GUI.getProjectPath();
String sourcePath [] = {"/bin/sh ", "-c ","source ~/set_env_WRF_gnu.sh"} ;
Runtime fortranAnalyser = Runtime.getRuntime();
try {
Process p = fortranAnalyser.exec("cp main.exe " + projectPath);
Process k = fortranAnalyser.exec(sourcePath);
BufferedReader is = new BufferedReader(new InputStreamReader(k.getInputStream()));
String line;
while ((line = is.readLine()) != null) {
System.out.println(line);
}
} catch (IOException ex) {
Logger.getLogger(Analyser_GUI.class.getName()).log(Level.SEVERE, null, ex);
}
}
Process p works fine and does indeed copy main.exe to the intended directory when the method is called. Process k however does not and this is where the issue is.
Thanks in advance.
The issue is "source" is internal command of BASH (you are using "sh" but that is just BASH in the simplified mode). So what you do is:
you spawn new process "sh" and source something there (setting some VARIABLES I guess)
the process ends and all VARIABLES are lost
you spawn another process, but VARIABLES are already gone
I am not sure if you use those variables later on, but according to the script name it is probably setting some. Don't do that like this.
By the way if you only want to execute script in bash, you don't need to source it. To get it's side effects, just execute it with:
String sourcePath [] = {"/bin/sh ", "/home/XYZ/set_env_WRF_gnu.sh"} ;
Please note you cannot use ~ in this case, use Java to get your home dir.
I'm trying to figure out how to open the system preferred editor for a given file.
Say, we have a file manager, written in Java. User goes to folder and sees the list of files. And, for example, there is a file Icon.jpg. User double clicks on the filename and file opens in system's preferred editor (i.e. Gimp). The main issue is - how to do that?
We can do Runtime.getRuntime().exec("something file"), but this way you should know which program is preferred in user environment. But how?
We also are able to do Desktop.getDesktop().edit(File file), but this way we cannot track process and aren't able to know then this child process is closed. Other issue - function doesn't work on linux (at least on Ubuntu 8.10). There is also Desktop.getDesktop().open(File file), but it forces to open file viewer, instead of system viewer for that file type.
I am searching for a solution all week, but didn't got any suitable and generic one. Do you know the other approaches to this question? For my project it would be enough if it would work on Windows+Linux+Mac.
Thank you for your answers and advices.
Edit on 2009-02-08 23:04
Other suggestion: can I force "application selection" window in Windows and in Linux, as in Mac with "open file"? For example, then you trying to open file, you are being asked to choose application from list of system preferred ones? (something like "Open with..." in Windows explorer). Do you know?
Seems that if you can't use java.awt.Desktop you have to distinguish between the OSes:
Windows:
RUNDLL32.EXE SHELL32.DLL,OpenAs_RunDLL <file.ext>
Linux:
edit <file.ext>
Mac:
open <file.ext>
HTH. Obviously, that is not very portable...
Check out the java.awt.Desktop object. In your case, you want to invoke edit()
If you want to ensure that a given platform supports this call, then you can do something like the following (I have not tested this code):
public boolean editFile(final File file) {
if (!Desktop.isDesktopSupported()) {
return false;
}
Desktop desktop = Desktop.getDesktop();
if (!desktop.isSupported(Desktop.Action.EDIT)) {
return false;
}
try {
desktop.edit(file);
} catch (IOException e) {
// Log an error
return false;
}
return true;
}
This isn't cross-platform, but on Mac OS X you can do
Runtime.getRuntime().exec("open filename");
The open(1) executable uses LaunchServices to pick the right program to execute, and then uses that to open the file named filename.
This will work in windows
Runtime.getRuntime().exec( "CMD /C START filename.ext " );
For JavaFX applications, we can use HostServices. This question covers how to use HostServices. This should work on Ubuntu (tested)/Windows (not tested) and Mac (not tested).
import java.io.File;
import java.io.IOException;
public class App extends Application {
}
File file = new File("/your/file/path");
HostServices hostServices = getHostServices();
hostServices.showDocument(file.getAbsolutePath());
getHostServices() is a method of JavaFX Application class.