I am very new to groovy and I am trying out this example from the Groovy in Action book. I have this fibonacci.groovy program and when trying to run the program with java command, I am getting the NoClassDefFound error.
The command I am using in the console is:
java -cp %GROOVY_HOME%/embeddable/groovy-all-2.2.0.jar;classes fibonacci
As you can see, I have mentioned the groovy-all jar in the classpath and I set the GROOVY_HOME variable. The classpath variable is not set, so I am assuming it has the default '.' value to find in the current folder itself. What am I doing wrong?
Aren't you missing the current folder in the classpath?
I'm on Linux, but if i compile a Groovy class with groovyc and then try to run it with java, i need to tell java where is my groovy-all.jar and also add the current dir to the classpath
So, this compilation works:
$ groovyc Fib.groovy
But this run doesn't runs:
$ java -cp $GROOVY_HOME/embeddable/groovy-all-2.2.0.jar:classes Fib
As it's missing the current dir in the path:
$ java -cp $GROOVY_HOME/embeddable/groovy-all-2.2.0.jar:. Fib
test for fib
Also note that if fibonacci is in a package, you need to type the full path to the class. So for this groovy source:
package up.foo
println "test for fib"
Compile:
$ groovyc Fib.groovy
We write the full package path to execute:
$ java -cp $GROOVY_HOME/embeddable/groovy-all-2.2.0.jar:. up.foo.Fib
There it is:
test for fib
Related
At the moment I am looking for another way to run my Java program from command line, other than adding it to a JAR file. My program has the following number of classes:
The name of the program file - MyProgram
Main class - Server1
second class - Client Handler
Package name - Items
3rd class - User1
4th class - User2
The main class and client handler alongside the package will have to run first in order for user 1 & user 2 to run, because they are client classes and are dependent on the main class.
javac *.java // compliles all java files in the dir
java MyClass // runs the particular file
If one class is dependent on another class that hasn't been compiled yet, the program won't run. So you should compile all files before trying to run the program dependent on other files.
If your files are packaged, then something like this
javac com.mypackage/.*java
java com.mypackage.MyClass
you must ensure that you add the location of your .class file to your classpath. So, if its in the current folder then add . to your classpath. Note that the windows classpath separator is a semi-colon ie ;
javac -cp . PackageName/*.java
java -cp . PackageName/ClassName_Having_main
Example. Suppose you have the following
Package Named: com.test
Class Name: Hello (Having main)
Java file is located inside "src/com/test/Hello.java"
then, from outside directory:
$ cd src
$ javac -cp . com/test/*.java
$ java -cp . com/test/Hello
Note that you can add -d to specify output directory of your class files whenever compiling
$ javac -d output_directory -cp . com/test/Hello
In windows the same thing will be working too, I already tried
Check out this from Oracle official site
Once you compile your code, you then run this from the top level:
java -cp . com.myprogram.MyProgram
That order thing you describe doesn't matter. They all get compiled together, and MyProgram will reference Server1, etc.
It may be more then you want to tackle right now but you might want to consider a build system like Maven. To start try out; How do I make my first Maven project?
You can use it to predefine the build order and if you want have it create a jar for you (or not).
Sounds like you will just need to open multiple command prompts and compile and run them in the order you need them to run. Let me know if I misunderstood question.
TO EXECUTE TWO JAVA PROGRAMS WHICH DEPENDS TO EACH OTHER.
(for example:two files Complex.java and Solution.java, where Soultion.java depends upon Complex.java.
So Complex.java should be compiled first and then the class file of Complex must be linked with Solution.java and then Solution.class must be executed for Output.)
REFER THE IMAGE WITH SYNTAX.
STEP 1:
COMPILE Complex.java
compiling Complex.java
syntax-
javac -d [path_where_class_File_build] [path_of_the_file\filename.java]
(Solution.java and Complex.java are Linked. ie-Solution.java calls Complex.java)
STEP 2:
COMPILE Solution.java
compiling Solution.java with linking Complex.class
with linking Complex.class(above created in step 1)
syntax-
javac -d [path_where_class_File_build] -cp [path_of_the_first_class_created] [path_of_the_file\filename.java]]
STEP 3:
EXECUTE THE Solution.class
java -cp [path_of_second_class_created] [class_Name]
(created in Step 3)
I have a program that I run from Eclipse successfully.
However, when I want to run it from terminal, I encounter the famous error:
"java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver"
on this line:
Class drvClass = Class.forName("oracle.jdbc.driver.OracleDriver");
PS:
I have the following in CLASSPATH:
/oracle/jdbc/lib/ojdbc6.jar
Also note that I compile it successfully (javac Test2.java). Then when I run it (java Test2), I get the following error:
Error: Could not find or load main class Test2
So I run:
java -classpath ~/Desktop/JDBC2/src Test2
It runs, but I get the above "ClassNotFoundException" though.
I found this question tricky: the reason is related to semicolon after jar file address.
At first I changed the directory of MySample.java to another directory (you can don't do that) like C:\
then I removed package address from the source code, at the end I run this command in cmd
java -cp path_to_oracle_driver.jar; MySample
P.S. If you want run it from terminal you have to remove package PackageAddress from the source code and compile it again.
As #yngwietiger mentioned above in the comments, using -classpath parameter when running the .class file, overrides the original CLASSPATH and the predefined ojdbc6.jar file. So we need to mention both when running:
java -classpath ~/Desktop/JDBC2/src:/oracle/jdbc/lib/ojdbc6.jar Test2
Or, as a better solution, we can add the current path to CLASSPATH (note the colon and dot at the end):
export CLASSPATH=$CLASSPATH:.
And, in order to run, we just need to type:
Java Test2
This is might be a common question but I am not able to add class path for a JAR file in UBUNTU. I have given below all the details I know:
java is located here:
the o/p of which java command is - /usr/bin/java
sudo vim /etc/bash.bashrc
export CLASSPATH=$CLASSPATH:/downloads/aws-java-sdk-1.3.24/lib/aws-java-sdk-1.3.24.jar
ps: downloads folder is directly under the root
sudo vim /etc/environment
CLASSPATH="/usr/lib/jvm/jdk1.7.0/lib: /downloads/aws-java-sdk-1.3.24/lib/aws-java-sdk-1.3.24.jar:"
As you can see, I have added the class path in bashrc and etc/environment... but still I am getting an error while trying to run the S3Sample.java which comes with awssdk for java.
when I compile the java file, I get the following errors:
ubuntu#domU-12-31-39-03-31-91:/downloads/aws-java-sdk-1.3.24/samples/AmazonS3$ javac S3Sample.java
S3Sample.java:25: error: package com.amazonaws does not exist
import com.amazonaws.AmazonClientException;
Now, I clearly understand that the JAR file is not added to the class path and so I am not getting the error. I've also tried javac with the class path option - but it does not work :(
PS: JAVA home is set correctly as other java programs work properly.
To set the classpath, it is in most cases better to use the the -cp or -classpath argument when calling javac and java. It gives you more flexibility to use different classpaths for different java applications.
With the -cp and -classpath arguments your classpath can contain multiple jars and multiple locations separated with a : (colon)
javac -cp ".:/somewhere/A.jar:/elsewhere/B.jar" MyClass.java
java -cp ".:/somewhere/A.jar:/elsewhere/B.jar" MyClass
The classpath entry in the example sets the classpath to contain the current working directory (.), and the two jar files A.jar and B.jar.
If you want to use the CLASSPATH environment variable you can do
export CLASSPATH=".:/somewhere/A.jar:/elsewhere/B.jar"
javac MyClass.java
java MyClass
I've got the following structure
lib/junit-4.10.jar
tests/Tester.java
tests/Tester.class
build/jar/jar_file.jar
(Tester belongs to package tests)
I can compile tests using
javac -cp build/jar/jar_file.jar:lib/junit-4.10.jar tests/*.java
However I can't seem to run tests:
java -cp build/jar/jar_file.jar:lib/junit-4.10.jar org.junit.runner.JUnitCore tests.Tester
or
java -cp build/jar/jar_file.jar:lib/junit-4.10.jar org.junit.runner.JUnitCore Tester
And I get the following output:
JUnit version 4.10
Could not find class: tests.Tester
Time: 0.001
OK (0 tests)
How do I resolve this Could not find class problem? I think it may be classpath related.
Assuming this is Linux/Mac (not Windows) and your path separator is correct (:), since your test class files exist in package subdirectories under the current working directory (.)
You need to add "." to your class path, for example:
java -cp .:build/jar/jar_file.jar:lib/junit-4.10.jar org.junit.runner.JUnitCore tests.Tester
The classpath should be semi colon separated (on Windows - not sure what you are using.)
java -cp build/jar/jar_file.jar;lib/junit-4.10.jar org.junit.runner.JUnitCore tests.Tester
Also with this command line you will need to run it in your project root
I am on Arch Linux, I just installed JRE and JDK and all the proper bin files (javac and java) are in /opt/java/bin/
I simply compiled a standard hello world, and compiled it with javac running javac ./hello.java and that made a class.
Now my problem is running it. I run java ./helloworld.class and it gives me an error, even if the file I point java to is non-existant:
Exception in thread "main" java.lang.NoClassDefFoundError: //helloworld/class
Caused by: java.lang.ClassNotFoundException: ..helloworld.class
(..omitted for clarity..)
Could not find the main class: ./helloworld.class. Program will exit.
You will notice the first line of the error, it munges the path //helloworld/class
When I feed java an absolute path, i.e java /home/foo/helloworld.class it gives the same error, but replaces the path's / with . in the first line, again munged.
What do you think is wrong? I really don't know why it is doing this..
When you run java, you just pass it the fully qualified class name (including package), not the file name.
java helloworld will look for helloworld.class.
java helloworld.class will look for helloworld/class.class
You do not run a file as
# java file.class
you run it as
# javac PATH/file.java
# java PATH/file
Do not add .class while using JAVA command.
Actually you should compile it like this
javac helloword.java
run the program
java helloword
And yet another thing: add command line option "-classpath ." or it short version "-cp .", i.e. your command line should look like:
java -cp . helloworld
this is if your class is in your current directory. Otherwise "." should be replaced by path where the class(es) may be found.