Develop Reference

How to pass arguments to pre compiled java code

I need to process a high volume of resumes. And want to use this parser:
https://github.com/antonydeepak/ResumeParser
But you run it in powershell with the file to read and the output file.
But I do not know how to automate this, so it read a whole folder containing the resumes.
I know some Java, but cant open the code. Is scripinting in powershell the way to go?
Thanks!

> java -cp '.\bin\*;..\GATEFiles\lib\*;..\GATEFILES\bin\gate.jar;.\lib\*'
code4goal.antony.resumeparser.ResumeParserProgram <input_file> [output_file]
Either make a batch file from an edited directory listing, or write a program.
As this is stackoverflow:
So starting with the same classpath (-cp ...) you can run your own program
public void static main(String[] args) throws IOException {
File[] files = new File("C:/resumes").listFiles();
File outputDir = new File("C:/results");
outputDir.mkDirs();
if (files != null) {
for (File file : files) {
String path = file.getPath();
if (path.endsWith(".pdf")) {
String output = new File(outputDir,
file.getName().replaceFirst("\\.\\w+$", "") + ".json").getPath();
String[] params = {path, output);
ResumeParserProgram.main(params);
// For creating a batch file >x.bat
System.out.println("java -cp"
+ " '.\\bin\\*;..\\GATEFiles\lib\\*;"
+ "..\\GATEFILES\\bin\\gate.jar;.\\lib\\*'"
+ " code4goal.antony.resumeparser.ResumeParserProgram"
+ " \"" + path + "\" \"" + output + "\"");
}
}
}
}
Check that this works, that ResumeParserProgram.main is reenterable.

Using URLClassLoader to load .class file

I'm aware that this question has been asked before:
How to use URLClassLoader to load a *.class file?
However I don't really understand due to the lack of example. I'm currently working on a project and trying to load user-given .class objects which can be located in any directories on the machine.
//Create URL to hash function class file
URL url_hashFunctionPath = new URL("file:///" + _sHashFunctionFilePath);
//Packet URL to a URL array to be used by URLClassLoader
URL[] urlA_hashFunctionPath = {url_hashFunctionPath};
//Load URL for hash function via a URL class loader
URLClassLoader urlCl_hashFunctionClassLoader = new URLClassLoader(urlA_hashFunctionPath);
//Load user hash function into class to initialize later (TEST: HARD CODE FOR NOW)
m_classUserHashClass = urlCl_hashFunctionClassLoader.loadClass(_sUserHashClassName);
The last line gave me a ClassNotFoundException, from my experiment & understanding the user-given class function has to be in the classpath?
PS: 1st time posting questions feel free to correct me where I did not follow the appropriate manner.
//SOLUTION
The solution that I arrived at with the generous help of [WillShackleford][1], this solution can load the a .class file in a given filepath. For more information refer to code and their given comments.
//The absolute file path to the class that is to be loaded (_sHashFunctionFilePath = absolute file path)
String pathToClassFile = _sHashFunctionFilePath;
System.out.println("File to class: " + _sHashFunctionFilePath);
//Declare the process builder to execute class file at run time (Provided filepath to class)
ProcessBuilder pb = new ProcessBuilder("javap", pathToClassFile);
try
{
//Start the process builder
Process p = pb.start();
//Declare string to hold class name
String classname = null;
//Declare buffer reader to read the class file & get class name
try(BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream())))
{
String line;
while(null != (line = br.readLine()))
{
if(line.startsWith("public class"))
{
classname = line.split(" ")[2];
break;
}
}
System.out.println("classname = " + classname);
}
catch(IOException _error)
{
}
//Declare file path to directory containing class to be loaded
String pathToPackageBase = pathToClassFile.substring(0, pathToClassFile.length() - (classname + ".class").length());
System.out.println("pathToPackageBase = " + pathToPackageBase);
try
{
//Create class to hold the class to be loaded via a URL class loader
Class clss = new URLClassLoader(
new URL[]{new File(pathToPackageBase).toURI().toURL()}
).loadClass(classname);
//Create ab object/instance of said class
Object test = clss.newInstance();
//Declare & create requested method from user hash function class (Method is work & takes no arguments)
Method method = clss.getMethod("work", null);
method.invoke(test, null);
}

In the directory /home/shackle/somedir/classes/pkg I have a file Test.class created from a java file with package pkg; eg :
package pkg;
public class Test {
public String toString() {
return "secret_string";
}
}
Then I load it with :
System.out.println(new URLClassLoader(
new URL[]{new File("/home/shackle/somedir/classes").toURI().toURL()}
).loadClass("pkg.Test").newInstance().toString());
Notice that I do not put the pkg/Test in the URL string but the load class argument has the pkg. prefix.
You can get the class name directly from the file like this:
Class clsReaderClss = ClassLoader.getSystemClassLoader().loadClass("jdk.internal.org.objectweb.asm.ClassReader");
System.out.println("clsReaderClss = " + clsReaderClss);
Constructor con = clsReaderClss.getConstructor(InputStream.class);
Object reader = con.newInstance(new FileInputStream(directFile));
Method m = clsReaderClss.getMethod("getClassName");
String name = m.invoke(reader).toString().replace('/', '.');
System.out.println("name = " + name);
An alternative that doesn't require access to internal classes.
String pathToClassFile = "/home/shackle/somedir/classes/pkg/Test.class";
ProcessBuilder pb = new ProcessBuilder("javap",pathToClassFile);
Process p = pb.start();
String classname = null;
try(BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()))) {
String line;
while(null != (line = br.readLine())) {
if(line.startsWith("public class")) {
classname = line.split(" ")[2];
break;
}
}
}
System.out.println("classname = " + classname);
Class can then be loaded with:
String pathToPackageBase = pathToClassFile.substring(0, pathToClassFile.length() - (classname + ".class").length());
System.out.println("pathToPackagBase = " + pathToPackageBase);
Class clss = new URLClassLoader(
new URL[]{new File(pathToPackageBase).toURI().toURL()}
).loadClass(classname);
System.out.println(clss.newInstance().toString());

Your _sHashFunctionFilePath needs to have the package name of the target class removed from it, so the ClassLoader will look in _sHashFunctionFilePath + package.name + HashFunction.class as the path to the file. If you don't do that, the ClassLoader won't be able to find the file.
So if the target class is my.great.HashFunction in HashFunction.class, then it needs to be in a directory called my/great/ if you want to use URLClassLoader. Then, you'd use /path/to as the file:/// URL for your URLClassLoader if the .class file was actually found in /path/to/my/great/HashFunction.class.

Can't make Files and Folders

So i'm working on a simple Windows Explorer replacement. I want to add the ability to create Folders and Files. For some reason, it only works when i'm in my root or c:/ folder, but as soon as it's somewhere else (for example C:\Program Files (x86)) it doesn't work. I either get a java.io.IOException: Access Denied when i create a File and when i try to create a folder, no Exception comes up, but no folder is created.
This is my code for a new file:
String location = getPath();
String name = JOptionPane.showInputDialog("Fill in the name of the new file. \nDon't forget to add file type (.txt, .pdf).", null);
if(name == null){
}
else {
File newFile = new File(location + "\\" + name);
boolean flag = false;
try {
flag = newFile.createNewFile();
} catch (IOException Io) {
JFrame messageDialog = new JFrame("Error!");
JOptionPane.showMessageDialog(messageDialog, "File creation failed with the following reason: \n" + Io);
}
}
This is my code for a new Folder:
String location = getPath();
String name = JOptionPane.showInputDialog("Fill in the name of the new folder.", null);
if(name == null){
}
else {
File newFolder = new File(location + "\\" + name);
boolean flag = false;
try {
flag = newFolder.mkdir();
} catch (SecurityException Se) {
JFrame messageDialog = new JFrame("Error!");
JOptionPane.showMessageDialog(messageDialog, "Folder creation failed with the following reason: \n" + Se);
}
}
I'm stuck right now and i have no idea what i'm doing wrong to get rid of the access denied error.
Short explenation of how this program works:
My program shows a list of all folders and files from a selected File.
That File is a field in the class JXploreFile called "currentFile", which behaves almost the same as a File.
When browsing through the folders, the currentFile is set to a new JXploreFile, containing the new folder you are in as File.
When creating a new folder/file, my program ask the path the user is currently browsing in with the method getPath().
Thanks for the help!
Image of my program:

Before you try to make any I/O operation just check if you have the permission
go to the parent directory (your case location)
then do something like
File f = new File(location);
if(f.canWrite()) {
/*your full folder creation code here */
} else {
}

try to put
String location ="c:\\user\<<youruser>>\\my documents"
or a folder with full perission to write

Weird exception in thread "main" java.io.FileNotFoundException I/O Java

I have this error when I am trying to read the file:
Exception in thread "main" java.io.FileNotFoundException: \src\product.txt (No such file or directory)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:120)
at dao.Inventory.readFile(Inventory.java:30)
at view.InventoryView.init(InventoryView.java:33)
at view.InventoryView.<init>(InventoryView.java:21)
at view.InventoryView.main(InventoryView.java:211)
But the thing is, I have the product.txt in my src folder.
My code is the following:
public void readFile() throws IOException {
// input file must be supplied in the first argument
InputStream istream;
File inputFile = new File("\\src\\product.txt");
istream = new FileInputStream(inputFile);
BufferedReader lineReader;
lineReader = new BufferedReader(new InputStreamReader(istream));
String line;
while ((line = lineReader.readLine()) != null) {
StringTokenizer tokens = new StringTokenizer(line, "\t");
// String tmp = tokens.nextToken();
// System.out.println("token " + tmp);
ActionProduct p = new ActionProduct();
prodlist.add(p);
String category = p.getCategory();
category = tokens.nextToken();
System.out.println("got category " +category);
int item = p.getItem();
item = Integer.parseInt(tokens.nextToken());
String name = p.getName();
System.out.println("got name " +name);
double price = p.getPrice();
price = Double.parseDouble(tokens.nextToken());
int units = p.getUnits();
units = Integer.parseInt(tokens.nextToken());
}
}
I don't think anything is wrong with my code. Also, I saw a similar post about a hidden extension like FILE.TXT.TXT, how would you show a hidden extension in MacOSX?? Any suggestions? (Would there be any other problem besides the hidden extension issue?)

/src/product.txt is an absolute path, so the program will try to find the file in the src folder of your root path (/). Use src/product.txt so the program will use this as a relative path.

It's possible (most likely?) that your Java code is not executing inside the parent folder of src, but instead inside a 'class' or a 'bin' folder with the compiled java .class files.
Assuming that 'src' and 'bin' are in the same directory, you could try ..\\src\\product.txt
See also http://en.wikipedia.org/wiki/Path_(computing)

As other commenters stated, the path is absolute and points to
\src\product.txt which is (hopefully) not where
your sources are stored.
The path separator should be set in an OS-independent manner using
the System.getProperty("path.separator") property. On a Unix system, you'll have trouble with hard coded backslashes as path separators. Keep it portable!
String pathSeparator = System.getProperty("path.separator");
String filePath = "." + pathSeparator + "src" + pathSeparator + "product.txt";
File file = new File(filePath);
or better yet:
// this could reside in a non-instantiable helper class somewhere in your project
public static String getRelativePath(String... pathElements) {
StringBuilder builder = new StringBuilder(".");
for (String pathElement : pathElements) {
builder.append(System.getProperty("path.separator");
builder.append(pathElement);
}
return builder.toString();
}
// this is where your code needs a path
...
new File(getRelativePath("src", "product.txt");
...

Determine which JAR file a class is from

I am not in front of an IDE right now, just looking at the API specs.
CodeSource src = MyClass.class.getProtectionDomain().getCodeSource();
if (src != null) {
URL jar = src.getLocation();
}
I want to determine which JAR file a class is from. Is this the way to do it?

Yes. It works for all classes except classes loaded by bootstrap classloader. The other way to determine is:
Class klass = String.class;
URL location = klass.getResource('/' + klass.getName().replace('.', '/') + ".class");
As notnoop pointed out klass.getResource() method returns the location of the class file itself. For example:
jar:file:/jdk/jre/lib/rt.jar!/java/lang/String.class
file:/projects/classes/pkg/MyClass$1.class
The getProtectionDomain().getCodeSource().getLocation() method returns the location of the jar file or CLASSPATH
file:/Users/home/java/libs/ejb3-persistence-1.0.2.GA.jar
file:/projects/classes

Checkout the LiveInjector.findPathJar() from Lombok Patcher LiveInjector.java. Note that it special cases where the file doesn't actually live in a jar, and you might want to change that.
/**
* If the provided class has been loaded from a jar file that is on the local file system, will find the absolute path to that jar file.
*
* #param context The jar file that contained the class file that represents this class will be found. Specify {#code null} to let {#code LiveInjector}
* find its own jar.
* #throws IllegalStateException If the specified class was loaded from a directory or in some other way (such as via HTTP, from a database, or some
* other custom classloading device).
*/
public static String findPathJar(Class<?> context) throws IllegalStateException {
if (context == null) context = LiveInjector.class;
String rawName = context.getName();
String classFileName;
/* rawName is something like package.name.ContainingClass$ClassName. We need to turn this into ContainingClass$ClassName.class. */ {
int idx = rawName.lastIndexOf('.');
classFileName = (idx == -1 ? rawName : rawName.substring(idx+1)) + ".class";
}
String uri = context.getResource(classFileName).toString();
if (uri.startsWith("file:")) throw new IllegalStateException("This class has been loaded from a directory and not from a jar file.");
if (!uri.startsWith("jar:file:")) {
int idx = uri.indexOf(':');
String protocol = idx == -1 ? "(unknown)" : uri.substring(0, idx);
throw new IllegalStateException("This class has been loaded remotely via the " + protocol +
" protocol. Only loading from a jar on the local file system is supported.");
}
int idx = uri.indexOf('!');
//As far as I know, the if statement below can't ever trigger, so it's more of a sanity check thing.
if (idx == -1) throw new IllegalStateException("You appear to have loaded this class from a local jar file, but I can't make sense of the URL!");
try {
String fileName = URLDecoder.decode(uri.substring("jar:file:".length(), idx), Charset.defaultCharset().name());
return new File(fileName).getAbsolutePath();
} catch (UnsupportedEncodingException e) {
throw new InternalError("default charset doesn't exist. Your VM is borked.");
}
}

Use
String path = <Any of your class within the jar>.class.getProtectionDomain().getCodeSource().getLocation().getPath();
If this contains multiple entries then do some substring operation.

private String resourceLookup(String lookupResourceName) {
try {
if (lookupResourceName == null || lookupResourceName.length()==0) {
return "";
}
// "/java/lang/String.class"
// Check if entered data was in java class name format
if (lookupResourceName.indexOf("/")==-1) {
lookupResourceName = lookupResourceName.replaceAll("[.]", "/");
lookupResourceName = "/" + lookupResourceName + ".class";
}
URL url = this.getClass().getResource(lookupResourceName);
if (url == null) {
return("Unable to locate resource "+ lookupResourceName);
}
String resourceUrl = url.toExternalForm();
Pattern pattern =
Pattern.compile("(zip:|jar:file:/)(.*)!/(.*)", Pattern.CASE_INSENSITIVE);
String jarFilename = null;
String resourceFilename = null;
Matcher m = pattern.matcher(resourceUrl);
if (m.find()) {
jarFilename = m.group(2);
resourceFilename = m.group(3);
} else {
return "Unable to parse URL: "+ resourceUrl;
}
if (!jarFilename.startsWith("C:") ){
jarFilename = "/"+jarFilename; // make absolute path on Linux
}
File file = new File(jarFilename);
Long jarSize=null;
Date jarDate=null;
Long resourceSize=null;
Date resourceDate=null;
if (file.exists() && file.isFile()) {
jarSize = file.length();
jarDate = new Date(file.lastModified());
try {
JarFile jarFile = new JarFile(file, false);
ZipEntry entry = jarFile.getEntry(resourceFilename);
resourceSize = entry.getSize();
resourceDate = new Date(entry.getTime());
} catch (Throwable e) {
return ("Unable to open JAR" + jarFilename + " "+resourceUrl +"\n"+e.getMessage());
}
return "\nresource: "+resourceFilename+"\njar: "+jarFilename + " \nJarSize: " +jarSize+" \nJarDate: " +jarDate.toString()+" \nresourceSize: " +resourceSize+" \nresourceDate: " +resourceDate.toString()+"\n";
} else {
return("Unable to load jar:" + jarFilename+ " \nUrl: " +resourceUrl);
}
} catch (Exception e){
return e.getMessage();
}
}

With Linux, I'm using a small script to help me find in which jar a class lies that can be used in a find -exec:
findclass.sh:
unzip -l "$1" 2>/dev/null | grep $2 >/dev/null 2>&1 && echo "$1"
Basically, as jars are zip, unzip -l will print the list of class resources, so you'll have to convert . to /. You could perform the replacement in the script with a tr, but it's not too much trouble to do it yourself when calling the script.
The, the idea is to use find on the root of your classpath to locate all jars, then runs findclass.sh on all found jars to look for a match.
It doesn't handle multi-directories, but if you carefully choose the root you can get it to work.
Now, find which jar contains class org.apache.commons.lang3.RandomUtils to you un-mavenize your project (...):
$ find ~/.m2/repository/ -type f -name '*.jar' -exec findclass.sh {} org/apache/commons/lang3/RandomUtils \;
.m2/repository/org/apache/commons/commons-lang3/3.7/commons-lang3-3.7.jar
.m2/repository/org/apache/commons/commons-lang3/3.6/commons-lang3-3.6.jar
.m2/repository/org/apache/commons/commons-lang3/3.6/commons-lang3-3.6-sources.jar
$