I'm having problems using ProcessBuilder to run a class in my project.
My code:
public class Main {
public static void main(String[] args) {
try {
String pathToJar = Main.class.getProtectionDomain().getCodeSource()
.getLocation().toURI().getPath();
ArrayList<String> params = new ArrayList<String>();
params.add("javaw");
params.add("-classpath");
params.add(pathToJar);
params.add("Program");
ProcessBuilder pb = new ProcessBuilder(params);
Process process = pb.start();
} catch (Exception e) {
e.printStackTrace();
}
}
}
class Program is in same project (same bin folder) and works fine if ran directly but this way I get the error "Could not find the main class: Program". Where is the error in my code?
Thanks in advance.
[EDIT]
I came to the conclution that is some code on my Program class giving error. Basicly only runs with "clean" main. At eclipse, Program class is importing some libraries that are inside a jar file. Don't I need to reference it in ProcessBuilder? If so, how?
In response to your edit:
You can add the current path by switching params.add(pathToJar); with params.add(System.getProperty("java.class.path").concat(";").concat(pathToJar));.
Where is the error in my code?
(You are launching the javaw executable, so that is not the problem. It is also not that your entry point method's signature is incorrect, because that would have given a different diagnostic.)
The problem is either that the class name is incorrect (e.g. if should be "come.pkg.Program"), or the pathname for the JAR file is incorrect.
Assuming that you have eliminated the possibility that the class name is incorrect, my guess is that you are trying to use a relative pathname for the JAR file, but there is some confusion over what the current directory is; i.e. the directory in which the pathname needs to be resolved. Try using an absolute pathname in the classpath parameter.
Related
I have a Java program that runs fine in Eclipse - when I export an executable jar file it gives me an exception.
I know it is because I am giving it the wrong path but I do not know how to fix. I tried using getClass().getResourceaAsStream() (or sth. like that) but that did not work as well.
The code I am using at the moment is the following:
line 31:
BufferedImage image = ImageIO.read(new File("/src/res/loading.png"));
Okay, so I created a simple project, made a directory called res and threw some images into it
Before anyone points out that this not Eclipse, it shouldn't matter, we've already established that the Jar file contains the res directory and images, it's about replicating the structure
I then wrote a really simple example...
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
System.out.println(Test.class.getResource("/res/0.jpg"));
System.out.println(getClass().getResource("/res/0.jpg"));
}
}
which outputs...
file:/.../Test/build/classes/res/0.jpg
file:/.../Test/build/classes/res/0.jpg
No, before any points out the IDE's environment is different from the command lines, I also ran it from the command line...
java -jar Test.jar
jar:file:/.../Test/dist/Test.jar!/res/0.jpg
jar:file:/.../Test/dist/Test.jar!/res/0.jpg
I'm getting a strange error where the parameter I supply to a method complains that it's not a directory but it IS in fact a directory with files in it...I don't understand what's wrong...
Toplevel:
public static File mainSchemaFile = new File("src/test/resources/1040.xsd");
public static File contentDirectory = new File("src/test/resources/input");
public static File outputDirectory = new File("src/test/resources/output");
DecisionTableBuilder builder =constructor.newInstance(log, contentDirectory, outputDirectory);
// Here is where the error occurs
builder.compile(mainSchemaFile);
The class I'm using:
public class DecisionTableBuilder {
public void compiler(File schemaFile) {
...
// It's complaining about contentDirectory, it goes to FileUtils class for this
Collection<File> flowchartFiles = FileUtils.listFiles(contentDirectory, mapExtension, true);
...
}
}
Here is the apache FileUtils class:
public class FileUtils {
private static void validateListFilesParameters(File directory, IOFileFilter fileFilter) {
if (!directory.isDirectory()) {
throw new IllegalArgumentException("Parameter 'directory' is not a directory");
}
if (fileFilter == null) {
throw new NullPointerException("Parameter 'fileFilter' is null");
}
}
}
Output: Parameter 'directory' is not a directory
Which is the error output I am getting...
Anyone have any idea what is happening here I'm super confused...any help will be greatly appreciated.
EDIT:
In my toplevel I added the following line:
if(contentDirectory.isDirectory()) {
System.out.println("Content Directory: "+contentDirectory);
}
Output: src/test/resources/input
You're pointing to the file and not a directory in mainSchemaFile variable. Reduce the path to the folder containing 1040.xsd - it should resolve the issue.
Error is thrown if paths cannot be reached
The file paths that you show do not tell where you try to run the code. If you are in your workspace, but you want to run it on a server, and the paths are meant to be on the server, see as follows:
I saw during debugging in the error logs of the console output of my own project that the code tried to get the data from my workspace. While coding, I thought that it would reach the files on the production server, but it did not.
Exception in thread "my_project" java.lang.IllegalArgumentException: Parameter 'directory' is not a directory
at org.apache.commons.io.FileUtils.validateListFilesParameters(FileUtils.java:545)
at org.apache.commons.io.FileUtils.listFiles(FileUtils.java:521)
at org.apache.commons.io.FileUtils.listFiles(FileUtils.java:691)
With the needed file copied to my workspace and the right path in the code, the error was gone since it found the directory.
In my program, my working directory was the repository from where I ran the code. I had to pull the repository on the server to run it with the working directory on the server, so that it could find the production directory for the input files.
I am currently making a small simple Java program for my Computer Science Final, which needs to get the path of the current running class. The class files are in the C:\2013\game\ folder.
To get this path, I call this code segment in my main class constructor:
public game(){
String testPath = this.getClass().getResource("").getPath();
//Rest of game
}
However, this command instead returns this String: "/" despite the correct output being "C:/2013/game"
Additionally, I attempted to rectify this by using this code:
public game(){
String testPath = this.getClass().getClassLoader().getResource("").getPath();
}
This returns a NullPointerException, which originates from the fact that getClassLoader() returns null, despite working on my Eclipse IDE. Any Ideas?
If you want to load a file in the same path as the code then I suggest you put it in the same root folder as the code and not the same path as the class.
Reason : class can be inside a jar, data file can be put in same jar but its more difficult to edit and update then.
Also suggest you see the preferences class suggested in comments : http://www.javacodegeeks.com/2011/09/use-javautilprefspreferences-instead-of.html though in some cases I think its okay to have your own data/ excel/csv/ java.util.Properties file
Not sure about why it is working in eclipse but I would suggest you focus on running it from a command prompt/ terminal as that is the 'real mode' when it goes live
You could just ask for your class
String s = getClass().getName();
int i = s.lastIndexOf(".");
if(i > -1) s = s.substring(i + 1);
s = s + ".class";
System.out.println("name " +s);
Object testPath = this.getClass().getResource(s);
System.out.println(testPath);
This will give you
name TstPath.class
file:/java/Projects/tests3b/build/classes/s/TstPath.class
Which is my eclipse build path ...
need to parse this to get the path where the class was loaded.
Remember:
App could be started from elsewhere
class can be in jar then path will be different (will point to a jar and file inside that
classpaths can be many at runtime and point 1
a class might be made at runtime via network/ Proxy / injection etc and thus not have a file source, so this is not a generic solution.
think what you want to acheive at a higher level and post that question. meaning why do you want this path?
do you want the app path :-
File f = new File("./");
f.getCanonicalPath();//...
So an app can be started from folder c:\app1\run\
The jar could be at c:\app1\libsMain\myapp.jar
and a helper jar could be at c:\commonlibs\set1
So this will only tell you where the JVM found your class, that may or maynot be what you need.
if inside a jar will give you some thing like this in unix or windows
jar:file:c:\app\my.jar!/s/TstPath.class
If package is s and class is TstPath, you can be sure this will work as the class has to be there ...
now to parse this you can look for your class name and remove / or \ till you get path you want. String lastIndexOf will help
You can use :
URL classURL = getClass().getProtectionDomain().getCodeSource().getLocation();
The call to getResource([String]) requires a path relative to the folder that contains the class it is being called from. So, if you have the following, anything you pass into MyClass.class.getResource([path]); must be a valid path relative to the com/putable/ package folder and it must point to a real file:
package com.putable;
public class MyClass{}
Using the empty string simply isn't valid, because there can never be a file name that equals the empty string. But, you could do getResource(getClass().getSimpleName()). Just remove the file name from the end of the path returned by that call and you will have the class directory you want.
ClassLoader loader = Test.class.getClassLoader();
System.out.println(loader.getResource("Test.class"));
also
Test.class.getProtectionDomain().getCodeSource().getLocation().getPath());
Try this.
import java.io.File;
public class TT {
/**
* #param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String path = TT.class.getResource("").getPath();
File file = new File(path);
System.out.println(file.getAbsolutePath());
}
}
Try use this code
public game()
{
String className = this.getClass().getSimpleName();
String testPath = this.getClass().getResource(className+".class");
System.out.println("Current Running Location is :"+testPath);
}
visit the link for more information
Find where java class is loaded from
Print out absolute path for a file in your classpath i.e. build/resources/main/someFileInClassPath.txt Disclaimer, this is similar to another solution on this page that used TT.class..., but this did not work for me instead TT..getClassLoader()... did work for me.
import java.io.File;
public class TT {
/**
* #param args
*/
public static void main(String[] args) {
String path = TT.getClassLoader().getResource("someFileInClassPath.txt").getPath();
File file = new File(path);
System.out.println(file.getAbsolutePath());
}
}
Because you used class.getResource(filePath).getpath() in a *.jar file. So the path includes "!". If you want to get content of file in *.jar file, use the following code:
MyClass.class.getResourceAsStream("/path/fileName")
public static void main(String args[]) throws IOException
{
Process p = Runtime.getRuntime().exec("java E:/workspace/JNIProgram/src/JNIProgram.class");
}
so I have this code and am trying to run the JNIProgram.class file however the program gets terminated instantly without doing its job (which is to create a new txt file and write to it)
So what am I doing wrong
The java command expects a Java class name, not a filename.
So the command java E:/workspace/JNIProgram/src/JNIProgram.class is wrong. If you try this manually from a command prompt window you'll get an error message.
The command should be something like this:
java -cp E:\workspace\JNIProgram\src JNIProgram
Note: What's after the -cp option is the classpath, and after that the fully-qualified class name (which is just JNIProgram, if the class is not in a package).
First make sure that you can run the command manually from the command line before you make it work from another Java program.
java -classpath ../classes;../jar;. parserTester
How can i get the functionality in the above command programmatically? Like, is it possible to run as:
java parserTester
and get the same result? I tried using URLClassLoader but it modifies the classpath and does not add to it.
Thanx!
Thanks for the response Milhous. But that is what i am trying to do.. How is it possible to get the jar into the classpath first? I tried using a custom classloader too :(
That works.. But sorry that i need to run it only as:
java parserTester
I would like to know if such a thing is possible???
It needs to be so bcoz i have parserTester.java and .class in a separate folder. I need to retain the file structure. The parserTester makes use of a jar in a separate jar folder.
You can use a java.net.URLClassLoader to load classes with any program defined list of URL's you wish:
public class URLClassLoader
extends SecureClassLoader
This class loader is used to load
classes and resources from a search
path of URLs referring to both JAR
files and directories. Any URL that
ends with a '/' is assumed to refer to
a directory. Otherwise, the URL is
assumed to refer to a JAR file which
will be opened as needed.
The AccessControlContext of the thread
that created the instance of
URLClassLoader will be used when
subsequently loading classes and
resources.
The classes that are loaded are by
default granted permission only to
access the URLs specified when the
URLClassLoader was created.
Since:
1.2
And a little fancy footwork can extend it to support using wildcarded pathnames to pick up entire directories of JARs (this code has some references to utility methods, but their implementation should be obvious in the context):
/**
* Add classPath to this loader's classpath.
* <p>
* The classpath may contain elements that include a generic file base name. A generic basename
* is a filename without the extension that may begin and/or end with an asterisk. Use of the
* asterisk denotes a partial match. Any files with an extension of ".jar" whose base name match
* the specified basename will be added to this class loaders classpath. The case of the filename is ignored.
* For example "/somedir/*abc" means all files in somedir that end with "abc.jar", "/somedir/abc*"
* means all files that start with "abc" and end with ".jar", and "/somedir/*abc*" means all files
* that contain "abc" and end with ".jar".
*
*/
public void addClassPath(String cp) {
String seps=File.pathSeparator; // separators
if(!File.pathSeparator.equals(";")) { seps+=";"; } // want to accept both system separator and ';'
for(StringTokenizer st=new StringTokenizer(cp,seps,false); st.hasMoreTokens(); ) {
String pe=st.nextToken();
File fe;
String bn=null;
if(pe.length()==0) { continue; }
fe=new File(pe);
if(fe.getName().indexOf('*')!=-1) {
bn=fe.getName();
fe=fe.getParentFile();
}
if(!fe.isAbsolute() && pe.charAt(0)!='/' && pe.charAt(0)!='\\') { fe=new File(rootPath,fe.getPath()); }
try { fe=fe.getCanonicalFile(); }
catch(IOException thr) {
log.diagln("Skipping non-existent classpath element '"+fe+"' ("+thr+").");
continue;
}
if(!GenUtil.isBlank(bn)) {
fe=new File(fe,bn);
}
if(classPathElements.contains(fe.getPath())) {
log.diagln("Skipping duplicate classpath element '"+fe+"'.");
continue;
}
else {
classPathElements.add(fe.getPath());
}
if(!GenUtil.isBlank(bn)) {
addJars(fe.getParentFile(),bn);
}
else if(!fe.exists()) { // s/never be due getCanonicalFile() above
log.diagln("Could not find classpath element '"+fe+"'");
}
else if(fe.isDirectory()) {
addURL(createUrl(fe));
}
else if(fe.getName().toLowerCase().endsWith(".zip") || fe.getName().toLowerCase().endsWith(".jar")) {
addURL(createUrl(fe));
}
else {
log.diagln("ClassPath element '"+fe+"' is not an existing directory and is not a file ending with '.zip' or '.jar'");
}
}
log.diagln("Class loader is using classpath: \""+classPath+"\".");
}
/**
* Adds a set of JAR files using a generic base name to this loader's classpath. See #link:addClassPath(String) for
* details of the generic base name.
*/
public void addJars(File dir, String nam) {
String[] jars; // matching jar files
if(nam.endsWith(".jar")) { nam=nam.substring(0,(nam.length()-4)); }
if(!dir.exists()) {
log.diagln("Could not find directory for Class Path element '"+dir+File.separator+nam+".jar'");
return;
}
if(!dir.canRead()) {
log.error("Could not read directory for Class Path element '"+dir+File.separator+nam+".jar'");
return;
}
FileSelector fs=new FileSelector(true).add("BaseName","EG",nam,true).add("Name","EW",".jar",true);
if((jars=dir.list(fs))==null) {
log.error("Error accessing directory for Class Path element '"+dir+File.separator+nam+".jar'");
}
else if(jars.length==0) {
log.diagln("No JAR files match specification '"+new File(dir,nam)+".jar'");
}
else {
log.diagln("Adding files matching specification '"+dir+File.separator+nam+".jar'");
Arrays.sort(jars,String.CASE_INSENSITIVE_ORDER);
for(int xa=0; xa<jars.length; xa++) { addURL(createUrl(new File(dir,jars[xa]))); }
}
}
private URL createUrl(File fe) {
try {
URL url=fe.toURI().toURL();
log.diagln("Added URL: '"+url.toString()+"'");
if(classPath.length()>0) { classPath+=File.pathSeparator; }
this.classPath+=fe.getPath();
return url;
}
catch(MalformedURLException thr) {
log.diagln("Classpath element '"+fe+"' could not be used to create a valid file system URL");
return null;
}
}
I have to agree with the other two posters, it sounds like you're overcomplicating a test class.
It's not that unusual to have the .java and .class files in separate folders, while depending on jar files in yet a third, without programmatically changing the classpath.
If you're doing it because you don't want to have to type the classpath on the command line everytime, I would suggest a shell script or batch file. Better yet, an IDE.
The question I really have is why are you doing trying to manage the classpath in code?
You could implement your own class loader, but that class/jar has to be in the classpath for it to be executed.
try
java -cp *.jar:. myClass
or
export CLASSPATH=./lib/tool.jar:.
java myClass
or
java -jar file.jar
You can write a batch file or shell script file to export the classpath and run the java program.
In Windows,
set classpath=%classpath%;../classes;../jars/*
java ParserTester
In Unix,
export classpath=%classpath%:../classes:../jars/*
java ParserTester
If you name the file name as parser.bat or parser.sh, you can just run that by calling parser in respective OS.
From java 1.6, you can include all the jars in a directory into the classpath just by saying /*
If you are trying to generate a java file dynamically, compile and add into the classpath, set the directory into which the class file gets generated in the classpath beforehand. It should load the class.
If you are modifying the already generated java class, basically recompiling after modification and if you want to load the new class, you need to use your custom class loader to avoid the caching of the class.
I think what you want is an "Execution Wrapper" or a platform specific "Launcher"... typically this component is used to detect your OS and architecture and dependencies and then makes adjustments before launching your application. It is an old school design pattern (talking 80's and earlier) but is still used a lot today. The idea is that you program can be system and environment agnostic and the launcher will make preparations and tell the software everything it needs to know. Many modern open source programs do this with Shell scripts and Batch Files, etc... Apache Tomcat for example. You could just as easily make the wrapper in java an have it launch the software with a command line exec (be sure to add " &" to the end of you exec command in *NIX so your wrapper can exit leaving only your software running... also lets you close the shell window without killing the process)
Did I understand right?! The only reason you have it that you want to launch your class without specifying the classpath and load it at runtime? ...
java parserTester
instead of
java -classpath ../classes;../jar;. parserTester
Probably I didn't get your reason. But if "that's" what you want you can do the following ( although it does not make much sense to me )
Launch the class
From the main method lauch another class an programatically set the classpath there.
End of history.
Something like the following "java -pseudo code "
public static void main( String [] args ) {
String classpath = "classes;../jar";
Runtime.getRuntime().execute("java + classpath + " parserTester ");
}
Please tell me if I get it right. If you want to do something else I would gladly help.
Excellent good post, in my case I did this to work well (note: Windows specific):
set classpath=%classpath%;../lib/*
java -cp %classpath% com.test.MyClass