Tutorial Addendum On Java - Beheading Ambiance

Output:

    

 

    
D:\write_20021217java_20021217s

    
emoryUsage

    
Memory acceptance afore arrangement allocation:

    
   Chargeless anamnesis = 1777248

    
   Absolute anamnesis = 2031616

    
   Best anamnesis = 134217728

    
   Anamnesis acclimated = 254368

    
Memory acceptance afterwards arrangement allocation:

    
   Chargeless anamnesis = 1897280

    
   Absolute anamnesis = 4132864

    
   Best anamnesis = 134217728

    
   Anamnesis acclimated = 2235584

    
Memory acceptance summary:

    
   Allocated to the arrangement = 2097152

    
   Anamnesis acceptance access = 1981216

    
   Aerial of individual arrangement = -115936

    

The achievement was actual surprising. An arrangement for autumn 2097152 bytes (2MB) of data was

    

allocated. But the anamnesis acceptance was added by alone 1981216 bytes. Somehow the JVM

    

freed up some anamnesis during the arrangement allocation process.

    

If you attending carefully on the ethics

    

of absolute anamnesis afore and afterwards the arrangement allocation, you can see that the JVM

    

had requested an added 2MB of anamnesis from the operating arrangement into adjustment to

    

have abundant anamnesis to accord to the array. My assumption is that the amplification of total

    

memory triggered a debris accumulating call, which removed some un-used altar in

    

the JVM .

    

One way to abstain the absolute anamnesis amplification is to adjure the JVM with a starting

    

total anamnesis of 4MB, using the afterward command:

    

 

    
>c:j2sdk1.4.1_01injava -cp. -Xms4m MemoryUsage

    

Output:

    

 

    
Memory acceptance afore arrangement allocation:

    
   Chargeless anamnesis = 3874400

    
   Absolute anamnesis = 4128768

    
   Best anamnesis = 134217728

    
   Anamnesis acclimated = 254368

    
Memory acceptance afterwards arrangement allocation:

    
   Chargeless anamnesis = 1777232

    
   Absolute anamnesis = 4128768

    
   Best anamnesis = 134217728

    
   Anamnesis acclimated = 2351536

    
Memory acceptance summary:

    
   Allocated to the arrangement = 2097152

    
   Anamnesis acceptance access = 2097168

    
   Aerial of individual arrangement = 16

    

This time the program formed as planed. The anamnesis acceptance added 16 bytes added than

    

the amount of bytes bare to abundance the data elements of the array. So the 16 bytes

    

is the aerial amount of anamnesis for a individual dimentional array. It is acclimated to abundance

    

the admeasurement of the arrangement and additional advice about the array.

    

Executing Operating Arrangement Commands

    

The Runtime instance aswell offers methods for the Java appliance program to execute

    

an operating arrangement command as a subprocess. The afterward program uses the exec()

    

method to assassinate chkdsk command:

    

 

    
/**

    
 * CheckDisk.java

    
 * Absorb (c) 2002 by Dr.  Yang

    
 */

    
import java.io.*;

    
public chic CheckDisk {

    
   clandestine changeless Cord cmd = "c:\winnt\system32\chkdsk /i /c c:";

    
   accessible changeless abandoned main(String[] a) {

    
      Runtime rt = Runtime.getRuntime();

    
      Action p = null;

    
      try {

    
         Action p = rt.exec(cmd);

    
         Clairvoyant in = new InputStreamReader(p.getInputStream());

    
         int c = in.read();

    
         while (c!=-1) {

    
            System.out.print((char)c);

    
            c = in.read();

    
         }

    
      } bolt (IOException e) {

    
         System.out.println(e.toString());

    
      }

    
   }

    
}

    

Output:

    

 

    
The blazon of the book arrangement is NTFS.

    
Volume characterization is Bounded Disk.

    
WARNING!  F constant not specified.

    
Running CHKDSK in read-only mode.

    
WARNING!  I constant specified.

    
WARNING!  C constant specified.

    
Your drive may still be base even afterwards active CHKDSK.

    
CHKDSK is acceptance files (stage 1 of 3)...

    
File analysis completed.

    
CHKDSK is acceptance indexes (stage 2 of 3)...

    
Index analysis completed.

    
CHKDSK is acceptance aegis descriptors (stage 3 of 3)...

    
Security descriptor analysis completed.

    
   2096482 KB absolute deejay space.

    
   1825111 KB in 20535 files.

    
      7004 KB in 1919 indexes.

    
         0 KB in bad sectors.

    
     42432 KB in use by the system.

    
     12544 KB active by the log file.

    
    221934 KB accessible on disk.

    
       512 bytes in anniversary allocation unit.

    
   4192964 absolute allocation units on disk.

    
    443869 allocation units accessible on disk.

    

Note that how the achievement of the subprocess captured and reprinted on the JVM

    

console.