...
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
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Eclipse {rarr} {rrar} 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}// TODO Auto-generated method stub{code} by {code} |
by
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System.out.println("Hello World!"){code}
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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 installation, it was located at
C:\Program Files\IBM\ILOG\CPLEX_Studio125\cplex\lib\cplex.jar
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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:
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} 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} |
| Wiki Markup |
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Run the code. The final line of output should of course be {{\[0.0, 1.0, 1.0, 0.0\]}}, up to some precision. |