error executing java class file

Question

I have the following file ~/workspace/A/A.java:

package A;
public class A{
    public static void main(String[]args){
        System.out.println("Hello world");
    }
}

compiling with ecj don't give me problems,but then I get this error when tring to execute:

~/workspace/A $ java A
Exception in thread "main" java.lang.NoClassDefFoundError: A (wrong name: A/A)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
~/workspace/A $ java -cp . A
Exception in thread "main" java.lang.NoClassDefFoundError: A (wrong name: A/A)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)

I tried this on Linux Mint 17 with openjdk-7-jre version 7u55-2.4.7-1ubuntu1

SparkOn · Accepted Answer · 2014-06-27 15:07:38Z

3

As you said you have the structure /workspace/A/A.java just open the terminal and browse to workspace directory then type the following command

For compiling

javac A/A.java

For executing

java A.A

edited Jun 27, 2014 at 15:07

answered Jun 27, 2014 at 15:00

SparkOn

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Comments

rahul pasricha · Accepted Answer · 2014-06-27 14:48:04Z

0

did you try compiling your class first and then executing it

javac A.java

java A

answered Jun 27, 2014 at 14:48

rahul pasricha

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Peter Jerald · Accepted Answer · 2014-06-27 14:49:31Z

0

1st you have to compile java program, using below command.

javac A.java

Then, run java A

answered Jun 27, 2014 at 14:49

Peter Jerald

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amolpg · Accepted Answer · 2014-06-27 14:58:38Z

0

First you need to compile using javac A.java

then you also need to specify classpath while running like

java -classpath . A

answered Jun 27, 2014 at 14:58

amolpg

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dethorpe · Accepted Answer · 2014-06-27 14:58:43Z

0

Don't know if ecj differs from javac, so make sure the A.class file has ended up in same dir as your java file (~/workspace/A/) after compiling and try this:

cd ~/workspace
java -cp . A.A

answered Jun 27, 2014 at 14:58

dethorpe

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A M · Accepted Answer · 2014-06-27 15:23:54Z

0

I recommend using a JAVA package name in lowercase especially when your classname is same as the package name. You might want to read this: http://docs.oracle.com/javase/tutorial/java/package/namingpkgs.html

answered Jun 27, 2014 at 15:23

A M

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