As promised...
Sun Java resources:
Java 2 (JDK 1.2) home: http://www.javasoft.com/products/jdk/1.2/
Download the Lose32 version of JDK 1.2.2: http://www.javasoft.com/products/jdk/1.2/download-windows.html
Java 1.2 (on-line) documentation: http://www.javasoft.com/products/jdk/1.2/docs/
Java 1.2 on-line package documentation: http://www.javasoft.com/products/jdk/1.2/docs/api/overview-summary.html
Java Tutorial: http://java.sun.com/docs/books/tutorial/
Non-Sun on-line resources:
Marty Hall's Java Programming Resources: http://www.apl.jhu.edu/~hall/java/
Java Lobby: http://www.javalobby.org/
Robert Hurd's CodeCollection Java source: http://www.codecollection.com/java/source/
The Giant Java Tree source code: http://www.gjt.org/pkgdoc/tree/
Cliff Berg's DDJ Java source code: http://www.digitalfocus.com/ddj/code/
Java in a Nutshell Examples source code: http://www.oreilly.com/catalog/jenut/examples/
FreeCode Java: http://www.freecode.com/cgi-bin/search.pl?query=java
EarthWeb Java: http://www.developer.com/downloads/freeware/java.html
Peter Ellehauge's Java resources: http://www.triathlon.dk/triguy/java/
Cygnus Java compiler (FYI): http://sourceware.cygnus.com/java/
Java Books:
Start with _Java in a Nutshell_: http://www.ora.com/catalog/javanut3/
Emacs resources (especially for Java):
The JDE page: http://sunsite.auc.dk/jde/
The Lose32 Emacs download page: http://www.cs.washington.edu/homes/voelker/ntemacs.html
The Gnu Emacs page: http://www.gnu.org/software/emacs/
Python resources:
Everything: http://www.python.org/
If you have any questions, just ask!
======================================================================
> Example, gcd (2520, 154)
>
> 2520 = 154 (16) + 56
> 154 = 56(2) + 42
> 56 = 42(1) + 14
> 42 = 14(3) + 0
Oh those clever Greeks...
I attach our recent hacks _plus_ a GCD implementation. The Gcd class probably ought to have a static method for gcd( n1, n2 ) & _no_ instance variables (fields). This version kinda has both. What do you think?
%MY_JAVA%\java.bat:
: Set up these environment variables appropriate to your file system
SET MY_JAVA=c:\temp\java
SET JAVA_HOME=c:\work\jdk1.2.2
SET CLASSPATH=%JAVA_HOME%\jre\lib\rt.jar;%MY_JAVA%
: Move to the source code directory (%MY_JAVA%\test)
CD %MY_JAVA%\test
: Compile source code
%JAVA_HOME%\bin\javac Test.java Gcd.java
: Run resulting classes
%JAVA_HOME%\bin\java test.Test -s 123456
%JAVA_HOME%\bin\java test.Gcd 2520 154
%MY_JAVA%\test\Test.java:
//////////////////////////////////////////////////////////////////////
//
// test.Test
//
//////////////////////////////////////////////////////////////////////
package test;
public class Test {
Test( int seed ) {
java.util.Random rand = new java.util.Random( seed );
for ( int i = 1; i < 10; ++i ) {
System.out.println( rand.nextInt( ) );
}
}
static void usage( ) {
System.out.println( "usage: java test.Test -s SEED" );
System.exit( -1 );
}
public static void main ( String[ ] args ) {
int seed = 12345;
// Parse the command line argument.
try {
for ( int i = 0; i < args.length; ++i ) {
if ( args[ i ].startsWith( "-" ) ) {
// Process command-line switch arguments.
if( args[ i ].startsWith( "-s" ) ) {
seed = Integer.parseInt( args[ ++i ] );
continue;
}
}
// Invalid command-line switch.
usage( );
}
}
catch ( NumberFormatException e ) {
usage( );
}
Test test = new Test( seed );
}
}
%MY_JAVA%\test\Gcd.java:
//////////////////////////////////////////////////////////////////////
//
// test.Gcd
//
//////////////////////////////////////////////////////////////////////
package test;
public class Gcd {
// Fields
int n1; // first integer
int n2; // second integer
// Constructors.
Gcd( int n1, int n2 ) {
this.n1 = java.lang.Math.max( n1, n2 ); // initialize first integer
this.n2 = java.lang.Math.min( n1, n2 ); // initialize second integer
}
// Methods.
public int gcd( ) {
return ( gcd( n1, n2 ) );
}
public int gcd( int n1, int n2 ) {
int modulus = n1 % n2; // saves one division if n1 > n2
if ( modulus == 0 ) {
return ( n2 );
}
else {
return ( gcd( n2, modulus ) );
}
}
static void usage( ) {
System.out.println( "usage: java test.Gcd INT1 INT2" );
System.exit( -1 );
}
public static void main ( String[ ] args ) {
int n1 = 2520;
int n2 = 154;
// Parse the command line argument.
try {
for ( int i = 0; i < args.length; ++i ) {
if ( args[ i ].startsWith( "-" ) ) {
// Process command-line switch arguments.
}
else {
// Process two command-line numerical arguments.
n1 = Integer.parseInt( args[ i++ ] );
n2 = Integer.parseInt( args[ i++ ] );
continue;
}
// Invalid command-line switch.
usage( );
}
}
catch ( java.lang.ArrayIndexOutOfBoundsException e ) {
usage( );
}
catch ( java.lang.NumberFormatException e ) {
usage( );
}
Gcd gcd = new Gcd( n1, n2 );
System.out.println( "test.Gcd: " +
"GCD( " + n1 + ", " + n2 + " ) = " + gcd.gcd( ) );
}
}
When I ran JAVA.BAT (after installing jdk1.2.2 in %JAVA_HOME% & these *.java files in %MY_JAVA%) I got the following output:
C:\temp\java\test>..\java.bat
C:\temp\java\test>SET MY_JAVA=c:\temp\java
C:\temp\java\test>SET JAVA_HOME=c:\work\jdk1.2.2
C:\temp\java\test>SET CLASSPATH=c:\work\jdk1.2.2\jre\lib\rt.jar;c:\temp\java
C:\temp\java\test>CD c:\temp\java\test
C:\temp\java\test>c:\work\jdk1.2.2\bin\javac Test.java Gcd.java
C:\temp\java\test>c:\work\jdk1.2.2\bin\java test.Test -s 123456
1774763047
-506496402
-41169962
2018695370
1083428877
298499967
-1264165101
1316144193
315415608
C:\temp\java\test>c:\work\jdk1.2.2\bin\java test.Gcd 2520 154
test.Gcd: GCD( 2520, 154 ) = 14
Have fun!
- dcp
p.s. Once you have the GCD then:
// LCM is the least common multiple of n1 & n2
public int lcm( int n1, int n2 ) {
return ( n1 * n2 / gcd( n1, n2 ) );
}
