...
Test
...
Eclipse
...
Open
...
eclipse
...
and
...
select
...
your
...
workspace.
...
If
...
you
...
start
...
out
...
with
...
a
...
blue
...
screen
...
with
...
some
...
circular
...
buttons
...
saying
...
Welcome
...
,
...
Tutorial
...
,
...
etc.,
...
click
...
Go
...
to
...
Workbench
...
.
...
Otherwise,
...
you
...
are
...
already
...
at
...
the
...
workbench.
...
Go
...
to
...
File
...
→
...
New
...
→
...
Java
...
Project
...
.
...
Name
...
your
...
project
...
sandbox
...
,
...
then
...
click
...
the
...
button
...
Finish
...
.
...
You
...
now
...
have
...
a
...
new
...
project
...
!
...
In
...
the
...
Package
...
Explorer
...
(left
...
side)
...
right
...
click
...
the
...
arrow
...
next
...
to
...
sandbox
...
to
...
expand
...
the
...
project.
...
Right
...
click
...
on
...
the
...
src
...
folder
...
and
...
then
...
go
...
to
...
new
...
→
...
class
...
.
...
Name
...
the
...
class
...
TestClass
...
.
...
Under
...
"Which
...
method
...
stubs
...
would
...
you
...
like
...
to
...
create?"
...
check
...
the
...
box
...
next
...
to
...
public
...
static
...
void
...
main(String
...
[
...
]
...
args)
...
.
...
Hit
...
the
...
Finish
...
button.
...
Then
...
replace
| Code Block |
|---|
}// TODO Auto-generated method stub{code} by {code} |
by
| Code Block |
|---|
System.out.println("Hello World!");{code}
|
Save
...
the
...
file
...
TestClass.java
...
by
...
hitting
...
Ctrl+s
...
or
...
the
...
save
...
button
...
(top
...
left
...
on
...
the
...
menu
...
bar).
...
To
...
run
...
your
...
code,
...
go
...
to
...
the
...
top
...
center
...
of
...
the
...
menu
...
bar
...
and
...
hit
...
the
...
run
...
icon
...
(its
...
a
...
green
...
circle
...
with
...
a
...
white
...
arrow
...
inside),
...
or
...
go
...
to
...
the
...
menu
...
bar
...
and
...
hit
...
Run
...
→
...
Run
...
.
...
The
...
Console
...
should
...
pop
...
up
...
on
...
the
...
bottom
...
with
...
the
...
output
...
of
...
your
...
program.
...
Test
...
Cplex
...
from
...
Eclipse
...
Open
...
Eclipse
...
and
...
expand
...
the
...
sandbox
...
project
...
we
...
created
...
previously.
...
Create
...
a
...
new
...
class
...
called
...
KnapsackSolver
...
.
...
Next
...
we
...
are
...
going
...
to
...
connect
...
to
...
Cplex.
...
Right
...
click
...
on
...
sandbox
...
in
...
the
...
package
...
explorer
...
and
...
select
...
new->folder
...
.
...
Give
...
it
...
the
...
name
...
lib
...
and
...
click
...
Finish
...
.
...
Find
...
the
...
file
...
cplex.jar
...
in
...
your
...
Cplex
...
installation.
...
On
...
my
...
Windows
...
installation,
...
it
...
was
...
located
...
at
...
- Windows:
...
C:\Program
...
Files\IBM\ILOG\CPLEX_Studio125\cplex\lib\cplex.jar
...
- Linux:
...
/opt/IBM/ILOG/CPLEX_Studio125/cplex/lib/cplex.jar
...
- Mac:
...
/Users/<yourusername>/Applications/IBM/ILOG/CPLEX_Studio125/cplex/lib/cplex.jar
...
Copy
...
the
...
file
...
cplex.jar
...
and
...
paste
...
it
...
in
...
the
...
newly
...
created
...
lib
...
folder
...
in
...
our
...
project.
...
Right
...
click
...
on
...
sandbox
...
in
...
the
...
package
...
explorer,
...
then
...
select
...
Build
...
Path
...
→
...
Configure
...
Build
...
Path...
...
Select
...
the
...
Libraries
...
tab,
...
then
...
hit
...
the
...
Add
...
JARs
...
button
...
(see
...
...
for
...
an
...
explanation
...
of
...
what
...
all
...
these
...
buttons
...
do).
...
Select
...
the
...
file
...
sandbox/lib/cplex.jar
...
,
...
then
...
hit
...
OK
...
until
...
we
...
have
...
exited
...
all
...
the
...
menus.
...
Open
...
up
...
KnapsackSolver
...
and
...
replace
...
the
...
text
...
of
...
the
...
file
...
with
...
the
...
following:
| Code Block |
|---|
} import java.util.Arrays; import ilog.concert.IloException; import ilog.concert.IloIntVar; import ilog.cplex.IloCplex; public class KnapsackSolver { public static double[] solveKnapsack(double[] values, double[] weights, double capacity){ if(weights.length != values.length){ throw new RuntimeException("values.length was " + values.length + " and weights.length was" + weights.length + " but they must be the same"); } try { IloCplex cplex = new IloCplex(); IloIntVar[] x = cplex.boolVarArray(values.length); cplex.addLe(cplex.scalProd(x, weights), capacity); cplex.addMaximize(cplex.scalProd(x, values)); cplex.solve(); return cplex.getValues(x); } catch (IloException e) { throw new RuntimeException(); } } public static void main(String[] args){ double[] values = new double[]{2,4,5,6}; double[] weights= new double[]{2,3,4,7}; double capacity = 8; double[] solution = solveKnapsack(values,weights,capacity); System.out.println(Arrays.toString(solution)); } } {code} |
Run
...
the
...
code.
...
The
...
final
...
line
...
of
...
output
...
should
...
of
...
course
...
be
...
[0.0,
...
1.0,
...
1.0,
...
0.0
...
]
...
,
...
up
...
to
...
some
...
precision.
...
Upload
...
the
...
output
...
of
...
the
...
program
...
as
...
your
...
assignment
...
...
If
...
you
...
get
...
the
...
error
...
Exception
...
in
...
thread
...
"main"
...
java.lang.UnsatisfiedLinkError:
...
ilog.cplex.Cplex.CPXopenCPLEX(
...
[I)J
...
then
...
your
...
PATH
...
was
...
not
...
set
...
properly.
...
The
...
easiest
...
way
...
to
...
deal
...
with
...
this
...
is
...
to
...
add
...
a
...
virtual
...
machine
...
argument
...
to
...
the
...
Run
...
Configuration.
...
Starting
...
from
...
the
...
menu
...
bar
...
at
...
the
...
top,
...
select
...
Run
...
→
...
Run
...
Configurations...
...
and
...
then
...
on
...
the
...
left,
...
make
...
sure
...
Java
...
Application
...
→
...
KnapsackSolver
...
is
...
selected.
...
In
...
the
...
center
...
panel,
...
pick
...
the
...
(
...
x
...
)=Arguments
...
tab.
...
In
...
the
...
second
...
box,
...
titled
...
VM
...
Arguments
...
,
...
add
...
the
...
line:
...
- Linux:
...
-Djava.library.path=/opt/ibm/ILOG/CPLEX_Studio125/cplex/bin/x86-64_sles10_4.1
...
- Windows:
...
-Djava.library.path="C:\Program
...
Files\IBM\ILOG\CPLEX_Studio125\cplex\bin\x64_win64"
...
- Mac:
...
-Djava.library.path=/Users/<yourusername>/Applications/IBM/ILOG/CPLEX_Studio125/cplex/bin/x86-64_darwin
...
As
...
you
...
can
...
see,
...
the
...
VM
...
argument
...
is
...
telling
...
java
...
the
...
directory
...
that
...
the
...
c
...
code
...
of
...
cplex
...
is
...
located
...
in.
| Warning | ||||
|---|---|---|---|---|
| =
| |||
| }
If your VM argument would have a space, you need to put quotes around it, as in the Windows example above. {warning} |
Finally,
...
hit
...
Run
...
on
...
the
...
bottom.