CODEWITHSUNDEEP
javacommand-line
omg
omg

Reputation: 139862

java command line execution

C:\Program Files\Java\jdk1.6.0_05\CoreJava\v1\v1ch2\Welcome>javac Welcome.java

C:\Program Files\Java\jdk1.6.0_05\CoreJava\v1\v1ch2\Welcome>java Welcome.class
Exception in thread "main" java.lang.NoClassDefFoundError: Welcome/class
Caused by: java.lang.ClassNotFoundException: Welcome.class
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClassInternal(Unknown Source)

C:\Program Files\Java\jdk1.6.0_05\CoreJava\v1\v1ch2\Welcome>java Welcome
Welcome to Core Java
by Cay Horstmann
and Gary Cornell

So my problem is,how does "java" find and executes a class?why can not directly specify the class file?

Upvotes: 1

Views: 1761

Answers (6)

Akash Rao
Akash Rao

Reputation: 928

First you need to give javac file_name.java after that Compiler will compile the java program and it generates the dot(.)class file.so you cannot directly give the class file without compiling the program.

Upvotes: -2

PeterMmm
PeterMmm

Reputation: 24630

The java program expects a class name as parameter, not a file name. As stated in the java manual: ( java )

java [ options ] class [ argument ... ]

Once this is clear read about the classpath.

Upvotes: 2

Eric Asberry
Eric Asberry

Reputation: 612

Its interpreting the dot in your filename as a package designation. As you advance in your knowledge of java, you will learn about packages and find that normally your class files are within a package, so for example, if the Welcome class was in the package "com.ericasberry", I would run it by typing java com.ericasberry.Welcome

Upvotes: 1

Rick
Rick

Reputation: 3840

The 'dot' is a delimiter. When you wrote Welcome.class, it was looking for a class named 'class' that is in the 'Welcome' package.

Upvotes: 2

ATorras
ATorras

Reputation: 4303

The parameter you pass to java.exe is the class name (with optional package), not the file name.

Regards.

Upvotes: 1

Nir Levy
Nir Levy

Reputation: 4740

If you add the .class java thinks you are looking for class named "class" in the package "Welcome". since there is not one you get an error.

Upvotes: 2

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