在ubuntu中使用Oracle JDK使用包编译Java文件

Question

I have successfully compiled this file and saved.

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

using

javac a.java

java A

but when I compile this file:

package B;

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

now, again using the same commands it do compile but never run

javac a.java

java A       
// could not find or load main class

Please guide me the exact command for the terminal to run the file.

Note: The file is named "a.java".

Answer 1

您需要指定标准名称，即packageName.ClassName ：

java B.A

Answer 2

您必须将目录更改为包含路径“ B”（您的程序包名称）的目录，然后调用java BA

Answer 3

As mentioned above, You need to specify the fully-qualified name, ie packageName.ClassName:

        >> javac a.java
        >> java B.A

But you need to create the directory named "packageName" yourself as jdk does not create one for you implicitly.