Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #33286

Re: about class dependancies

Show all headers | View raw

On 12/2/2015 8:26 PM, regis wrote:
> On 12/03/15 02:05, Stefan Ram wrote:
>> regis <regis.barbanchon@free.fr> writes:
>>> It still seems to work if it is made final...
>>
>> echo >A.java public final class A { public static void main( final
>> java.lang.String[] args ){ java.lang.System.out.println( B.x ); }}
>> echo >B.java public final class B { public static final int x = 1; }
>> javac A.java
>> javac B.java
>> java A
>> RENAME A.class hide.class
>> echo >B.java public final class B { public static final int x = 2; }
>> javac B.java
>> DELETE A.class
>> RENAME hide.class A.class
>> java A
>>
>>    Now it still prints 1, not 2.
>>
>>    The above script assume Microsoft® Windows.
>>    You might have to adjust it for your environment.
>
> Ah, interesting...
> so a non-updated file A.class can indeed be tricked by a change in B...

What is happening is seen with this:

public class B {
     public static final int K = 123;
}

public class A {
     public static void main(String[] args) {
         System.out.println(B.K);
         System.out.println(123);
     }
}

C:\Work>javap -c A
Compiled from "A.java"
public class A {
   public A();
     Code:
        0: aload_0
        1: invokespecial #1                  // Method 
java/lang/Object."init>":()V
        4: return

   public static void main(java.lang.String[]);
     Code:
        0: getstatic     #2                  // Field 
java/lang/System.out:Ljava/io/PrintStream;
        3: bipush        123
        5: invokevirtual #4                  // Method 
java/io/PrintStream.println:(I)V
        8: getstatic     #2                  // Field 
java/lang/System.out:Ljava/io/PrintStream;
       11: bipush        123
       13: invokevirtual #4                  // Method 
java/io/PrintStream.println:(I)V
       16: return
}

A.class does not contain a named reference to B.K instead
A.class contains the while of B.K from the time of compilation.

Arne

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

about class dependancies regis <regis.barbanchon@free.fr> - 2015-12-03 00:40 +0100
  Re: about class dependancies Lew <lewbloch@gmail.com> - 2015-12-02 16:32 -0800
    Re: about class dependancies regis <regis.barbanchon@free.fr> - 2015-12-03 01:49 +0100
      Re: about class dependancies regis <regis.barbanchon@free.fr> - 2015-12-03 02:26 +0100
        Re: about class dependancies Arne Vajhøj <arne@vajhoej.dk> - 2015-12-02 21:55 -0500
          Re: about class dependancies Arne Vajhøj <arne@vajhoej.dk> - 2015-12-02 21:58 -0500
        Re: about class dependancies Steven Simpson <ss@my.domain.invalid> - 2015-12-03 15:15 +0000
          Re: about class dependancies Arne Vajhøj <arne@vajhoej.dk> - 2015-12-03 19:49 -0500
      Re: about class dependancies Lew <lewbloch@gmail.com> - 2015-12-16 18:27 -0800
        Re: about class dependancies Steven Simpson <ss@my.domain.invalid> - 2015-12-17 08:39 +0000
          Re: about class dependancies Lew <lewbloch@gmail.com> - 2015-12-17 13:36 -0800
            Re: about class dependancies Mike Amling <mamling@chaff.us> - 2015-12-21 08:29 -0600
  Re: about class dependancies regis <regis.barbanchon@free.fr> - 2015-12-03 02:07 +0100
    Re: about class dependancies Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-12-03 08:06 -0500

csiph-web