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Java: I do not Understand the Relative Paths

I've got following maven project structure as also seen in here (ProjectStructure) :
-maws20.algorithm
|-src/main/resources
|-images
|-menuBanner
|-linearSearchMenuBannerUnsorted.png
|-src/main/java
|-linearSearch.menu
|-LinearSearchMenuBanner.java
I am trying to load that .png image inside of the LinearSearchMenuBanner.java-File with the following Line:
#Override
public Image loadBackgroundImage() {
return new Image(LinearSearchMenuBanner.class.
getResource("/images/menuBanner/linearSearchMenuBannerUnsorted.png").toString());
}
Is this not the correct relative path? Because I get the following error:
...
Caused by: java.lang.NullPointerException: Cannot invoke "java.net.URL.toString()" because the return value of "java.lang.Class.getResource(String)" is null
at linearSearch.menu.LinearSearchMenuBanner.loadBackgroundImage(LinearSearchMenuBanner.java:20)
...
(Line 20 is the line shown above)
I thought I understood the relative paths in Java. ^^'
Thank you for any help.

Remove the first back slash /, which actually means absolute path not the relative path.
Try this:
#Override
public Image loadBackgroundImage() {
File resource = new ClassPathResource("images/menuBanner/linearSearchMenuBannerUnsorted.png").getFile();
return new Image(new String(Files.readAllBytes(resource.toPath()));
}
To know more, you can visit this link: spring-classpath-file-access

Thanks for all your help. I don't know what went wrong, but when i create a completly new Workspace after that create all files new and copy the source code to the new files. Then it works fine.
I dont know why...
But thank you very much :)

I guess this is related to your packaging. The image needs to be on the servers file system, the JAR resources will not work!
ClassPathResource
Supports resolution as java.io.File if the class path resource resides in the file system, but not for resources in a JAR. Always supports resolution as URL.
You are in package search.menu and you need to access the file resource in images/menuBanner So you need to load a resource:

new ClassPathResource(“../../images/menuBanner/linearSearchMenuBannerUnsorted.png
“, LinearSearchMenuBanner
.class).getFile();



Hava a look into other options here:
https://www.baeldung.com/spring-classpath-file-access

Why Scala on Mac fails when run in unicode directory

I am attempting to simply compile a helloworld scala file from within a directory named using unicode characters but the scala compiler fails to run. It succeeds when I change directory's out the unicode named folder.
Detail
Given a classic Helloworld.scala class such as the one below
that is located in the directory:
/Users/me/Dev/Company/𝔘𝔫𝔦𝔠𝔬𝔡𝔢/code_folder
I am unable to run scalac on the code if my current directory is in code_folder which is the root directory for the Helloworld.scala. When I change directories out of the folder with the unicode name /𝔘𝔫𝔦𝔠𝔬𝔡𝔢, the compiler works just fine on the same code. So it would seem that scalac doesnt work when attempting to compile code while in a folder with unicode characters.
Why is that? Is this a system error? An unparsed unicode error between the OS starting the scalac process?
object Main{
def main(args: Array[String]): Unit = {
println("Hello world")
}
}
I expected a compiled file. The error I get is this
Exception in thread "main" java.lang.ExceptionInInitializerError
at scala.tools.util.PathResolver$Environment$.scalaExtDirs(PathResolver.scala:77)
at scala.tools.util.PathResolver$Defaults$.scalaExtDirs(PathResolver.scala:127)
at scala.tools.nsc.settings.StandardScalaSettings.$init$(StandardScalaSettings.scala:31)
at scala.tools.nsc.settings.MutableSettings.<init>(MutableSettings.scala:28)
at scala.tools.nsc.Settings.<init>(Settings.scala:19)
at scala.tools.nsc.Driver.process(Driver.scala:53)
at scala.tools.nsc.Driver.main(Driver.scala:80)
at scala.tools.nsc.Main.main(Main.scala)
Caused by: java.lang.IllegalArgumentException: Error decoding percent encoded characters
at java.base/sun.net.www.ParseUtil.decode(ParseUtil.java:209)
at java.base/jdk.internal.loader.FileURLMapper.getPath(FileURLMapper.java:64)
at java.base/jdk.internal.loader.FileURLMapper.exists(FileURLMapper.java:73)
at java.base/jdk.internal.loader.URLClassPath$JarLoader.getJarFile(URLClassPath.java:802)
at java.base/jdk.internal.loader.URLClassPath$JarLoader.access$900(URLClassPath.java:692)
at java.base/jdk.internal.loader.URLClassPath$JarLoader$1.run(URLClassPath.java:751)
at java.base/jdk.internal.loader.URLClassPath$JarLoader$1.run(URLClassPath.java:744)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/jdk.internal.loader.URLClassPath$JarLoader.ensureOpen(URLClassPath.java:743)
at java.base/jdk.internal.loader.URLClassPath$JarLoader.<init>(URLClassPath.java:718)
at java.base/jdk.internal.loader.URLClassPath$3.run(URLClassPath.java:486)
at java.base/jdk.internal.loader.URLClassPath$3.run(URLClassPath.java:469)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/jdk.internal.loader.URLClassPath.getLoader(URLClassPath.java:468)
at java.base/jdk.internal.loader.URLClassPath.getLoader(URLClassPath.java:437)
at java.base/jdk.internal.loader.URLClassPath.findResource(URLClassPath.java:280)
at java.base/jdk.internal.loader.BuiltinClassLoader.findResourceOnClassPath(BuiltinClassLoader.java:479)
at java.base/jdk.internal.loader.BuiltinClassLoader.findResource(BuiltinClassLoader.java:303)
at java.base/java.lang.ClassLoader.getResource(ClassLoader.java:1393)
at java.base/java.lang.ClassLoader.getSystemResource(ClassLoader.java:1658)
at java.base/java.lang.ClassLoader.getSystemResourceAsStream(ClassLoader.java:1762)
at java.base/java.lang.Class.getResourceAsStream(Class.java:2607)
at scala.util.PropertiesTrait.scalaProps(Properties.scala:39)
at scala.util.PropertiesTrait.scalaProps$(Properties.scala:37)
at scala.tools.reflect.WrappedProperties$AccessControl$.scalaProps$lzycompute(WrappedProperties.scala:49)
at scala.tools.reflect.WrappedProperties$AccessControl$.scalaProps(WrappedProperties.scala:49)
at scala.util.PropertiesTrait.scalaPropOrNone(Properties.scala:71)
at scala.util.PropertiesTrait.scalaPropOrNone$(Properties.scala:71)
at scala.tools.reflect.WrappedProperties$AccessControl$.scalaPropOrNone(WrappedProperties.scala:49)
at scala.util.PropertiesTrait.$init$(Properties.scala:83)
at scala.tools.reflect.WrappedProperties$AccessControl$.<init>(WrappedProperties.scala:49)
at scala.tools.reflect.WrappedProperties$AccessControl$.<clinit>(WrappedProperties.scala)
... 8 more
Version:
scalac -version
Scala compiler version 2.12.8 -- Copyright 2002-2018, LAMP/EPFL and Lightbend, Inc.
MacOS version 10.13.6

Not really a solution, but some piece of information:
I set up my folder this way:
/home/nicolas/Private/𝔘𝔫𝔦𝔠𝔬𝔡𝔢/
When the ClassLoader tries to load the classes of your project it makes a list of paths where to lookup classes as a list of URLClassPath
Now when the code goes on and it tries to parse these paths, it calls sun.net.www.ParseUtil.decode()
When I put a breakpoint in here, I can see that the path for our class is:
/home/nicolas/Private/%ed%a0%b5%ed%b4%98%ed%a0%b5%ed%b4%ab%ed%a0%b5%ed%b4%a6%ed%a0%b5%ed%b4%a0%ed%a0%b5%ed%b4%ac%ed%a0%b5%ed%b4%a1%ed%a0%b5%ed%b4%a2/target/scala-2.12/classes/
so it somehow translated 𝔘𝔫𝔦𝔠𝔬𝔡𝔢 into a percent encoded string : %ed%a0%b5%ed%b4%98%ed%a0%b5%ed%b4%ab%ed%a0%b5%ed%b4%a6%ed%a0%b5%ed%b4%a0%ed%a0%b5%ed%b4%ac%ed%a0%b5%ed%b4%a1%ed%a0%b5%ed%b4%a2
This in turn creates a CharsetDecoder for UTF-8:
CharsetDecoder dec = ThreadLocalCoders.decoderFor("UTF-8")
.onMalformedInput(CodingErrorAction.REPORT)
.onUnmappableCharacter(CodingErrorAction.REPORT);
and tries to decode the above url but it fails and that is why the classes can't be loaded.
Now if I go here https://www.branah.com/unicode-converter and tries to convert 𝔘𝔫𝔦𝔠𝔬𝔡𝔢 to a % encoded string, it gives me
%f0%9d%94%98%f0%9d%94%ab%f0%9d%94%a6%f0%9d%94%a0%f0%9d%94%ac%f0%9d%94%a1%f0%9d%94%a2
And if when I debug, I change the url using this encoded string value, ie
/home/nicolas/Private/%f0%9d%94%98%f0%9d%94%ab%f0%9d%94%a6%f0%9d%94%a0%f0%9d%94%ac%f0%9d%94%a1%f0%9d%94%a2/target/scala-2.12/classes/
Then it parses it properly and keeps going.
So I don't know where it gets that %ed%a0%b5%ed%b4%98%ed%a0%b5%ed%b4%ab%ed%a0%b5%ed%b4%a6%ed%a0%b5%ed%b4%a0%ed%a0%b5%ed%b4%ac%ed%a0%b5%ed%b4%a1%ed%a0%b5%ed%b4%a2
The interesting thing is that if I use the same website and try to convert back %ed%a0%b5%ed%b4%98%ed%a0%b5%ed%b4%ab%ed%a0%b5%ed%b4%a6%ed%a0%b5%ed%b4%a0%ed%a0%b5%ed%b4%ac%ed%a0%b5%ed%b4%a1%ed%a0%b5%ed%b4%a2 then I also get 𝔘𝔫𝔦𝔠𝔬𝔡𝔢
So I am a bit confused

Trying to read *.xlsx file using POI API

I am trying to read an *.xlsx file and i receive quite a lot of errors in the console. I am a beginner at this and please note that if i try to read *.xls files i have no problems there.
This is the code that i use:
public class XlsxTest {
public static void main(String[] args) throws IOException {
FileInputStream fis = new FileInputStream(new File("autotest2.xlsx"));
XSSFWorkbook wb = new XSSFWorkbook(fis);
XSSFSheet sheet = wb.getSheetAt(0);
FormulaEvaluator formulaEvaluator = wb.getCreationHelper().createFormulaEvaluator();
for (Row row : sheet) {
for (Cell cell : row) {
switch (formulaEvaluator.evaluateInCell(cell).getCellType()) {
case Cell.CELL_TYPE_NUMERIC:
System.out.println(cell.getNumericCellValue() + "\t\t");
break;
case Cell.CELL_TYPE_STRING:
System.out.println(cell.getStringCellValue() + "\t\t");
break;
}
}
System.out.println();
}
}
}
When i try to run this i receive the following errors:
Exception in thread "main" org.apache.poi.POIXMLException: java.lang.reflect.InvocationTargetException
at org.apache.poi.xssf.usermodel.XSSFFactory.createDocumentPart(XSSFFactory.java:62)
at org.apache.poi.POIXMLDocumentPart.read(POIXMLDocumentPart.java:465)
at org.apache.poi.POIXMLDocument.load(POIXMLDocument.java:173)
at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:278)
at XlsxTest.main(XlsxTest.java:18)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at org.apache.poi.xssf.usermodel.XSSFFactory.createDocumentPart(XSSFFactory.java:60)
... 4 more
Caused by: java.lang.ExceptionInInitializerError
at org.apache.xmlbeans.impl.schema.BuiltinSchemaTypeSystem.fillInType(BuiltinSchemaTypeSystem.java:1025)
at org.apache.xmlbeans.impl.schema.BuiltinSchemaTypeSystem.<clinit>(BuiltinSchemaTypeSystem.java:223)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.xmlbeans.XmlBeans.getNoType(XmlBeans.java:856)
at org.apache.xmlbeans.XmlBeans.<clinit>(XmlBeans.java:881)
at org.openxmlformats.schemas.drawingml.x2006.main.ThemeDocument$Factory.parse(Unknown Source)
at org.apache.poi.xssf.model.ThemesTable.<init>(ThemesTable.java:83)
... 9 more
Caused by: java.lang.RuntimeException: Installation Problem??? Couldn't load messages: Can't find bundle for base name org.apache.xmlbeans.impl.regex.message, locale en_US
at org.apache.xmlbeans.impl.regex.RegexParser.setLocale(RegexParser.java:88)
at org.apache.xmlbeans.impl.regex.RegexParser.<init>(RegexParser.java:78)
at org.apache.xmlbeans.impl.regex.ParserForXMLSchema.<init>(ParserForXMLSchema.java:28)
at org.apache.xmlbeans.impl.regex.RegularExpression.setPattern(RegularExpression.java:2996)
at org.apache.xmlbeans.impl.regex.RegularExpression.setPattern(RegularExpression.java:3009)
at org.apache.xmlbeans.impl.regex.RegularExpression.<init>(RegularExpression.java:2975)
at org.apache.xmlbeans.impl.regex.SchemaRegularExpression.<init>(SchemaRegularExpression.java:27)
at org.apache.xmlbeans.impl.regex.SchemaRegularExpression.<init>(SchemaRegularExpression.java:23)
at org.apache.xmlbeans.impl.regex.SchemaRegularExpression$1.<init>(SchemaRegularExpression.java:44)
at org.apache.xmlbeans.impl.regex.SchemaRegularExpression.buildKnownPatternMap(SchemaRegularExpression.java:43)
at org.apache.xmlbeans.impl.regex.SchemaRegularExpression.<clinit>(SchemaRegularExpression.java:38)
... 19 more
Can anyone help me with this issue? I hope that i provided the necessary information.
Thank you!

Rename jar of lib in zip or simply open org/apache/xmlbeans/impl/regex of loaded lib.
Find file message.properties (and message_xx.properties if necessary).
Put file(s) in used library by org/apache/xmlbeans/impl/regex path.
Profit!

I experienced the very similar exception when using Apache POI: a java.lang.ExceptionInInitializerError, caused by "java.lang.RuntimeException: Installation Problem??? Couldn't load messages: Can't find bundle for base name org.apache.xmlbeans.impl.regex.message" in XMLBeans.
Looked completely weird. Code worked on one machine but failed this way on another for no apparent reason.
After LOTS of debugging hours, I found out the reason was COMPLETELY unrelated to Excel, POI or XMLBeans: my project was located in the folder ending with "!". The solution was simply to rename the folder.
I guess the author had something similar happening, and indeed the linked post about Libre Office has nothing to do with this problem. Instead, the linked post should be the following: Unable to open resources in directories which end with an exclamation mark (!)

Got this error ONLY in junit test. Application runs perfectly fine. So check your case as well.
For test, following Sarck's suggestion worked. #4 is little confusing. So below is simple process.. works fine for 2.6 version of xmlbeans library.
In your project where this is failing, create a file named message.properties under src/test/resources/org/apache/xmlbeans/impl/regex folder. (src/test/resources is typical maven root resource folder). Add following content in that file
parser.parse.1=Wrong character.
parser.parse.2=Invalid reference number.
parser.next.1=A character is required after \\.
parser.next.2='?' is not expected. '(?:' or '(?=' or '(?!' or '(?<' or '(?#' or '(?>'?
parser.next.3='(?<=' or '(?<!' is expected.
parser.next.4=A comment is not terminated.
parser.factor.1=')' is expected.
parser.factor.2=Unexpected end of the pattern in a modifier group.
parser.factor.3=':' is expected.
parser.factor.4=Unexpected end of the pattern in a conditional group.
parser.factor.5=A back reference or an anchor or a lookahead or a lookbehind is expected in a conditional pattern.
parser.factor.6=There are more than three choices in a conditional group.
parser.atom.1=A character in U+0040-U+005f must follow \\c.
parser.atom.2=A '{' is required before a character category.
parser.atom.3=A property name is not closed by '}'.
parser.atom.4=Unexpected meta character.
parser.atom.5=Unknown property.
parser.cc.1=A POSIX character class must be closed by ':]'.
parser.cc.2=Unexpected end of the pattern in a character class.
parser.cc.3=Unknown name for a POSIX character class.
parser.cc.4='-' is invalid here.
parser.cc.5=']' is expected.
parser.cc.6='[' is invalid in a character class. Write '\\['.
parser.cc.7=']' is invalid in a character class. Write '\\]'.
parser.cc.8='-' is an invalid character range. Write '\\-'.
parser.ope.1='[' is expected.
parser.ope.2=')' or '-[' or '+[' or '&[' is expected.
parser.ope.3=The range end code point is less than the start code point.
parser.descape.1=Invalid Unicode hex notation.
parser.descape.2=Overflow in a hex notation.
parser.descape.3='\\x{' must be closed by '}'.
parser.descape.4=Invalid Unicode code point.
parser.descape.5=An anchor must not be here.
parser.process.1=This expression is not supported in the current option setting.
parser.quantifier.1=Invalid quantifier. A digit is expected.
parser.quantifier.2=Invalid quantifier. Invalid quantity or a '}' is missing.
parser.quantifier.3=Invalid quantifier. A digit or '}' is expected.
parser.quantifier.4=Invalid quantifier. A min quantity must be <= a max quantity.
parser.quantifier.5=Invalid quantifier. A quantity value overflow.
Duplicate this file as message_en.properties at same location.
If you are using newer version of xmlbeans jar then get content of this file from Apache source - replace version in url

cmu sphinx4 java - Runtime exception caused by FileNotFoundException

I have recently made a Java project with Sphinx4. I found this code online, and I slimmed it down to this to test if Sphinx4 was working:
public class App
{
private static final String ACOUSTIC_MODEL =
"resource:/edu/cmu/sphinx/models/en-us/en-us";
private static final String DICTIONARY_PATH =
"resource:/edu/cmu/sphinx/models/en-us/cmudict-en-us.dict";
public static void main(String[] args) throws Exception {
Configuration configuration = new Configuration();
configuration.setAcousticModelPath(ACOUSTIC_MODEL);
configuration.setDictionaryPath(DICTIONARY_PATH);
configuration.setGrammarName("dialog");
LiveSpeechRecognizer jsgfRecognizer =
new LiveSpeechRecognizer(configuration);
jsgfRecognizer.startRecognition(true);
while (true) {
String utterance = jsgfRecognizer.getResult().getHypothesis();
if (utterance.startsWith("hello")) {
System.out.println("Hello back!");
}
else if (utterance.startsWith("exit")) {
break;
}
}
jsgfRecognizer.stopRecognition();
}
}
However, it gave me this error:
Exception in thread "main" java.lang.RuntimeException: Allocation of search manager resources failed
at edu.cmu.sphinx.decoder.search.WordPruningBreadthFirstSearchManager.allocate(WordPruningBreadthFirstSearchManager.java:247)
at edu.cmu.sphinx.decoder.AbstractDecoder.allocate(AbstractDecoder.java:103)
at edu.cmu.sphinx.recognizer.Recognizer.allocate(Recognizer.java:164)
at edu.cmu.sphinx.api.LiveSpeechRecognizer.startRecognition(LiveSpeechRecognizer.java:47)
at com.weebly.controllingyourcomputer.bartimaeus.App.main(App.java:27)
Caused by: java.io.FileNotFoundException:
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(FileInputStream.java:195)
at java.io.FileInputStream.<init>(FileInputStream.java:138)
at java.io.FileInputStream.<init>(FileInputStream.java:93)
at sun.net.www.protocol.file.FileURLConnection.connect(FileURLConnection.java:90)
at sun.net.www.protocol.file.FileURLConnection.getInputStream(FileURLConnection.java:188)
at java.net.URL.openStream(URL.java:1038)
at edu.cmu.sphinx.linguist.language.ngram.SimpleNGramModel.open(SimpleNGramModel.java:403)
at edu.cmu.sphinx.linguist.language.ngram.SimpleNGramModel.load(SimpleNGramModel.java:277)
at edu.cmu.sphinx.linguist.language.ngram.SimpleNGramModel.allocate(SimpleNGramModel.java:114)
at edu.cmu.sphinx.linguist.lextree.LexTreeLinguist.allocate(LexTreeLinguist.java:334)
at edu.cmu.sphinx.decoder.search.WordPruningBreadthFirstSearchManager.allocate(WordPruningBreadthFirstSearchManager.java:243)
... 4 more
I thought it might be something about it not being able to find the paths for ACOUSTIC_MODEL or DICTIONARY_PATH, so I changed the resource: strings to things like %HOME%\\Downloads\\sphinx4-5prealpha-src\\sphinx4-5prealpha-src\\sphinx4-data\\src\\main\\resources\\edu\\cmu\\sphinx\\models\\en-us or paths with forward slashes or with C:\Users\Username\... but none of the paths worked. I know the paths exist because I copy and pasted them from the properties window of the actual resources.
So my question is: is it some of the code that I deleted from the original source code that is causing this error, is it something wrong with the paths, or is it entirely different?
EDIT
By the way, I am using Maven to build my project. I added the dependencies specified on the Sphinx4 website to my pom.xml, but it didn't work (it didn't recognize imports such as edu.com.sphinx.xxx) so I downloaded the JARs from the website they said to download them from and added them to my projects "Libraries" in my Java Build Path in Eclipse.

is it some of the code that I deleted from the original source code that
is causing this error
Yes, you deleted too much.
To recognize with grammar you need to make three calls:
configuration.setGrammarPath(GRAMMAR_PATH);
configuration.setGrammarName(GRAMMAR_NAME);
configuration.setUseGrammar(true);

Logic.class.getResource("effects\\newball.wav"); returns null

I've got the problem that the following code snip returns null:
System.out.println(Logic.class.getResource("effects\\newball.wav"));
I have a source folder in my project called effects. in this folder there's the referred file. I think there's a syntax error... Because THE FILE IS THERE. I must refer in this way (means with getResource) to my file because I will export it as jar later.
Thank you

Your effect directory should be a direct child of the src dir. Also in which case, you need a / to start the string path. So you would need this
System.out.println(Logic.class.getResource("/effects/newball.wav"));
ProjectRoot
src
effect
newball.wav
What I normally do using an IDE is just create a new package and name it whatever I want the file to be - in your case "effect". It's easier that way.
UPDATE
"I did it exatly so, but it still returns null"
It works fine for me
package stackoverflow;
public class Test {
public static void main(String[] args) {
System.out.println(Test.class.getResource("/effects/stack_reverse.png"));
}
}
Output: file:/C:/Android/workspace/StackOverflow/bin/effects/stack_reverse.png

Resource paths should use forward slashes, regardless of the filesystem on the machine you are using: try "effects/newball.wav"
See http://docs.oracle.com/javase/7/docs/technotes/guides/lang/resources.html (Under "resources, Names, and Contexts -- "The name of a resource is independent of the Java implementation; in particular, the path separator is always a slash (/).")