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Error creating file using new File(directory).mkdir() [duplicate]

This question already has answers here:
Java - mkdir() not writing directory
(2 answers)
Closed 4 years ago.
I used new File(directory).mkdir() to create a new folder.
When i setdirectory = "C:\\Users\\livw\\Desktop\New folder\\5b27233480c016706f62a30a",
it works.
But when i add one more child folder to the directory: directory = "C:\\Users\\livw\\Desktop\\New folder\\5b27233480c016706f62a30a\\Samples",it doesn't create the folder.
How can i fix it?

Short and sweet,
Use mkdirs() instead of mkdir().
Hope it helps
Please in future refer to documentation.

directory = "C:\Users\livw\Desktop\New folder\5b27233480c016706f62a30a"
kindly check the directory address as file separator is not properly given before new Folder
import java.io.File;`
public class FileCreation {
public static void main(String[] args) {
new File("C:\\Users\\Master\\Desktop\\Horse\\demo\\devil").mkdir();
new File("C:\\Users\\Master\\Desktop\\Horse\\demo\\devil"+File.separator+"a").mkdir();
}
}

java.lang.NoClassDefFoundError: org/apache/commons/io/FileUtils [duplicate]

This question already has answers here:
How to solve this java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream?
(6 answers)
Closed 6 years ago.
I'm using IntelliJ and I am trying to use the FileUtils.copyFile() method. When I use that method I get this error:
Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: org/apach
e/commons/io/FileUtils
Here is the code that uses the copy file method:
import org.apache.commons.io.FileUtils;
...
try {
File destJAR = new File("c:/X-Dock/MP3Player.jar");
File playerJAR = new File(MP3Player); //"MP3Player" is a string that is defined earlier.
FileUtils.copyFile(playerJAR, destJAR);
}catch (IOException e){
e.printStackTrace();
}
I imported the Apache Commons JAR "commons-io-2.4" into the IntelliJ project by going to
File -> Project Structure -> Libraries -> Add -> Java -> "commons-io-2.4.jar"
Any help would be greatly appreciated.

Follow these steps to resolve your problem.
or you can edit configuration file
build.gradle
dependencies {
compile files('libs/commons-io-2.4.jar')
}

Keyboard cannot be resolved [duplicate]

This question already has answers here:
Java: Input strings with keyboard class
(5 answers)
Closed 9 years ago.
Im a newbie on Java. I get an error. These are my simple codes:
public class AreaRect {
public static void main(String[] args) {
int height, width, area;
System.out.print("yukseklik?");
height = Keyboard.readInt();
System.out.print("genislik?");
width = Keyboard.readInt();
area = height * width;
System.out.print(area);
}
}
and I get this error:
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
Keyboard cannot be resolved
Keyboard cannot be resolved
at AreaRect.main(AreaRect.java:8)
I have a Keyboard.class file in the same directory with AreaRect.java..
Please can you tell me where am I wrong?

You need to organize your files into packages.
Move both Java files to a folder, e.g., mypackage. Then, add the following line to the top of each file:
package mypackage;
You can also have subpackages with nested folders. For example, the folder structure:
com
example
mypkg
AreaRect.java
Keyboard.java
could use the package com.example.mypkg.

If you are trying to compile your class via commandline with javac AreaRect.java, it will work to have the Keyboard.class file in the same folder.
If you are however trying to run this in Eclipse, it won't work until you add the .class file to a seperate folder and then add said folder to your buildpath via "Properties->Java Build Path->Add Class Folder".

Problems using Matlab Builder JA

First of all I would like to thank in advance everyone for reading such a long post. I really appreciate your help.
The thing is that I've been doing some research on how to "connect" Matlab and Java for a project I am working on for university. I figured that the most suitable option was using Matlab Builder JA, but I'm having a lot of troubles with it.
I follow step by step the instructions described on a tutorial (the link of the video in below) but get compilation errors over and over, and I really don't know how to fix them. The tutorial is about creating a Java package (demo.jar) with MATLAB ("com.demo"), which contains a class (MLTestClass) with a function makeSqr(n) which returns an n × n square matrix. Then I go to Eclipse, I add to the project both libraries javabuilder.jar and demo.jar and then create the following class:
public class Driver {
public static void main (String[] args) {
MLTestClass x = null;
Object result [] = null;
try {
x = new MLTestClass ();
result = x.makeSqr (1, 5);
System.out.println (result [0]);
} catch (MWException e) {
e.printStackTrace();
}
}
}
Of course I import com.demo.* and com.mathworks.toolbox.javabuilder.*.
Here are the errors the console gives me:
Exception in thread "main" java.lang.ExceptionInInitializerError
at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration.getProxyLibraryDir(MCRConfiguration.java:163)
at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration$MCRRoot.get(MCRConfiguration.java:77)
at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration$MCRRoot.<clinit>(MCRConfiguration.java:87)
at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration.getMCRRoot(MCRConfiguration.java:92)
at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration$ModuleDir.<clinit>(MCRConfiguration.java:66)
at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration.getModuleDir(MCRConfiguration.java:71)
at com.mathworks.toolbox.javabuilder.internal.MWMCR.<clinit>(MWMCR.java:1573)
at com.demo.DemoMCRFactory.(DemoMCRFactory.java:122)
at com.demo.MLTestClass.(MLTestClass.java:63)
at Driver.main(Driver.java:12)
Caused by: java.lang.NullPointerException
at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration$ProxyLibraryDir.get(MCRConfiguration.java:143)
at com.mathworks.toolbox.javabuilder.internal.MCRConfiguration$ProxyLibraryDir.<clinit>(MCRConfiguration.java:158)
... 10 more
Just in case, link tutorial (it's the video): http://www.mathworks.nl/products/javabuilder/description2.html
Anyone has any ideas what the problem could be? It says something about NullPointerException, but I don't know how to solve it as the constructor is provided by the class created with MATLAB. I didn't have any issues installing MCR, and by the way I have MacOS, which I hope is not the source of the problem :).
Again, sorry for the long post and thank you for your time.
Béntor.

Yes, please install MCR. The installation also mentions about setting environmental variables like LD_LIBRARY_PATH etc. If you are using eclipse, i would recommend you update the environmental variables
right click->
properties ->
run/debug settings->
environmental variables
I also had to make sure that variable MCR_CACHE_ROOT pointed to different directory since my home directory was not big enough.

You have install MCR (avaliable in http://www.mathworks.com/products/compiler/mcr/index.html)

None of the above solutions helped me (I already had MCR installed and Macs use DYLD_LIBRARY_PATH instead of LD_LIBRARY_PATH), and noone else online seemed to know. Finally in desperation, I tried editing the DYLD_LIBRARY_PATH and finally got it to work by removing the last part of it: /Applications/MATLAB/MATLAB_Compiler_Runtime/v82/sys/java/jre/maci64/jre/lib
Now the demo application from the tutorial works.
Next comes trying to make my code work.

OS X Paths for Run-Time Deployment
Use these setenv commands to set your MATLAB Runtime paths.
setenv DYLD_LIBRARY_PATH \
mcr_root/version/runtime/maci64 \
mcr_root/version/bin/maci64 \
mcr_root/version/sys/os/maci64
Source: http://www.mathworks.com/help/compiler_sdk/java/mcr-path-settings-for-run-time-deployment.html

can I load user packages into eclipse to run at start up and how?

I am new to java and to the eclipse IDE.
I am running Eclipse
Eclipse SDK
Version: 3.7.1
Build id: M20110909-1335
On a windows Vista machine.
I am trying to learn from the book Thinking in Java vol4.
The author uses his own packages to reduce typing. However the author did not use Eclipse and this is where the problem commes in..
This is an example of the code in the book.
import java.util.*;
import static net.mindview.util.print.*;
public class HelloWorld {
public static void main(String[] args) {
System.out.println("hello world");
print("this does not work");
}
this is the contents of print.Java
//: net/mindview/util/Print.java
// Print methods that can be used without
// qualifiers, using Java SE5 static imports:
package net.mindview.util;
import java.io.*;
public class Print {
// Print with a newline:
public static void print(Object obj) {
System.out.println(obj);
}
// Print a newline by itself:
public static void print() {
System.out.println();
}
// Print with no line break:
public static void printnb(Object obj) {
System.out.print(obj);
}
// The new Java SE5 printf() (from C):
public static PrintStream
printf(String format, Object... args) {
return System.out.printf(format, args);
}
} ///:~
The error I get the most is in the statement.
Import static net.mindview.util.print.*;
On this staement the Eclipse IDE says it cannot resolve net
also on the
print("this does not work");
The Eclipse IDE says that the class print() does not exist for the class HelloWorld.
I have been trying to get these to work, but with only limited success, The autor uses another 32 of these packages through the rest of the book.
I have tried to add the directory to the classpath, but that seems to only work if you are using the JDK compiler. I have tried to add them as libraries and i have tried importing them into a package in a source file in the project. I have tried a few other things but cant remember them all now.
I have been able to make one of the files work, the print.java file I gave the listing for in this message. I did that by creating a new source folder then making a new package in that foldeer then importing the print.java file into the package.
But the next time I try the same thing it does not work for me.
What I need is a way to have eclipse load all these .java files at start up so when I need them for the exercises in the book they will be there and work for me, or just an easy way to make them work everytime.
I know I am not the only one that has had this problem I have seen other questions about it on google searches and they were also asking about the Thinking In Java book.
I have searched this site and others and am just not having any luck.
Any help with this or sugestions are welcome and very appreciated.
thank you
Ok I have tried to get this working as you said, I have started a new project and I removed the static from the import statement, I then created a new source folder, then I created a new package in the source folder. Then I imported the file system and selected the the net.mindview.util folder.
Now the immport statement no longer gives me an error. But the the print statement does, the only way to make the print statement work is to use its fully qualified name. Here is the code.
import net.mindview.util.*;
public class Hello2 {
public static void main(String[] args) {
Hello2 test = new Hello2();
System.out.println();
print("this dooes not work");
net.mindview.util.Print.print("this stinks");
}
}
The Error on the print statement is:
The method print(String) is undefined for the type Hello2
and if I try to run it the error I get is:
Exception in thread "main" java.lang.Error: Unresolved compilation problem:
The method print(String) is undefined for the type Hello2
at Hello2.main(Hello2.java:6)
The Statement::::: net.mindview.util.Print.print("this stinks") is the fully qualified print statement and it does not throw an error but it does totally defeat the purpose of the print.java file..
If you have any questions please ask Ill get back to you as soon as I can.

I've had similar issues. I solved it by following the steps below:
Click File->New->Java Project. Fill in UtilBuild for the ProjectName. Chose the option "Use project folder as root and click 'Finish'.
Right-click on UtilBuild in the PackageExplorer window and click New->package. For the Package Name, fill in net.mindview.util
Navigate within the unzipped Thinking In Java (TIJ) folder to TIJ->net\mindview\util. Here you will find all the source code (.java) files for util.
Select all the files in the net\mindview\util folder and drag them to the net.mindview.util package under UtilBuild in Eclipse. Chose the 'Copy Files' option and hit 'OK'.
You will probably already have the 'Build Automatically' option checked. If not, go to Project and click 'Build Automatically'. This will create the .class files from the .java source files.
In Eclipse, right-click on the project you were working on (the one where you couldn't get that blasted print() method to work!) Click Properties and Java Build Path->Libraries. Click 'Add Class Folder...' check the box for UtilBuild (the default location for the .class files).
I think the confusion here arises due to CLASSPATH. If you use Eclipse to build and run your code then Eclipse manages your CLASSPATH. (You don't have to manually edit CLASSPATH in the 'Environment Variables' part of your computer properties, and doing so changes nothing as far as Eclipse Build and Run are concerned.)
In order to call code that exists outside your current project (I will name this 'outside code' for convenience) you need to satisfy three things:
A. You need to have the .class files for that code (as .class files or inside a JAR)
B. You need to indicate in your source code where to look for the 'outside code'
C. You need to indicate where to start looking for the 'outside code'
In order to satisfy these requirements, in this example we:
A. Build the project UtilBuild which creates the .class files we need.
B. Add the statement import static net.mindview.util.Print.*; in our code
C. Add the Class Folder library in Eclipse (Java Build Path->Libraries).
You can investigate the effect of Step C by examining the .classpath file that lives directly in your project folder. If you open it in notepad you will see a line similar to the following:
<classpathentry kind="lib" path="/UtilBuild>
You should combine this with your import statement to understand where the compiler will look for the .class file. Combining path="/UtilBuild" and import static net.mindview.util.Print.*; tells us that the compiler will look for the class file in:
UtilBuild/net/mindview/util
and that it will take every class that we built from the Print.java file (Print.*).
NOTE:
There is no problem with the keyword static in the statement
import static net.mindview.util.Print.*;
static here just means that you don't have to give specify the class name from Print.java, just the methods that you want to call. If we omit the keyword static from the import statement, then we would need to qualify that print() method with the class it belongs to:
import net.mindview.util.Print.*;
//...
Print.print("Hello");
which is slightly more verbose than what is achieved with the static import.
OPINION:
I think most people new to Java will use Eclipse at least initially. The Thinking in Java book seems to assume you will do things via command line (hence it's guidance to edit environment variables in order to update CLASSPATH). This combined with using the util folder code from very early in the book I think is a source of confusion to new learners of the language. I would love to see all the source code organised into an Eclipse project and available for download. Short of that, it would be a nice touch to include the .class files in just the 'net/mindview/util' folder so that things would be a little easier.

U should import package static net.mindview.util not static net.mindview.util.Print
and you should extend the class Print to use its method.......

You should remove the static keyword from your import decleration, this: import static net.mindview.util.print.*; becomes this: import net.mindview.util.print.*;
If that also does not work, I am assuming you did the following:
Create your own project;
Start copying code directly from the book.
The problem seems to be that this: package net.mindview.util; must match your folder structure in your src folder. So, if your src folder you create a new package and name it net.mindview.util and in it you place your Print class, you should be able to get it working.
For future reference, you should always make sure that your package decleration, which is at the top of your Java class, matches the package in which it resides.
EDIT:
I have seen your edit, and the problem seems to have a simple solution. You declare a static method named print(). In java, static methods are accessed through the use of ClassName.methodName(). This: print("this dooes not work"); will not work because you do not have a method named print which takes a string argument in your Hello2 class. In java, when you write something of the sort methodName(arg1...), the JVM will look for methods with that signature (method name + parameters) in the class in which you are making the call and any other classes that your calling class might extend.
However, as you correctly noted, this will work net.mindview.util.Print.print("this stinks");. This is because you are accessing the static method in the proper way, meaning ClassName.methodName();.
So in short, to solve your problem, you need to either:
Create a method named print which takes a string argument in your Hello2 class;
Call your print method like so: Print.print("this stinks");
Either of these two solutions should work for you.

In my case I've dowloaded and decompressed the file TIJ4Example-master.zip. in eclipse workspace folder. The three packages : net.mindview.atunit, net.mindview.simple and net.mindview.util are in this point of the project :
and java programs runs with no problems (on the right an example of /TIJ4Example/src/exercises/E07_CoinFlipping.java)