Using Concert Technology in Java

This Java application solves the model in this way.

Here is a Java application using CPLEX with Concert Technology to solve the example. An expanded form of this example is discussed in detail in Java tutorial.

import ilog.concert.*;
import ilog.cplex.*;

public class Example {
  public static void main(String[] args) {
    try {
      IloCplex cplex = new IloCplex();

      double[]    lb = {0.0, 0.0, 0.0};
      double[]    ub = {40.0, Double.MAX_VALUE, Double.MAX_VALUE};
      IloNumVar[] x  = cplex.numVarArray(3, lb, ub);

      double[] objvals = {1.0, 2.0, 3.0};
      cplex.addMaximize(cplex.scalProd(x, objvals));

      cplex.addLe(cplex.sum(cplex.prod(-1.0, x[0]),
                            cplex.prod( 1.0, x[1]),
                            cplex.prod( 1.0, x[2])), 20.0);
      cplex.addLe(cplex.sum(cplex.prod( 1.0, x[0]),
                            cplex.prod(-3.0, x[1]),
                            cplex.prod( 1.0, x[2])), 30.0);

      if ( cplex.solve() ) {
        cplex.output().println("Solution status = " + cplex.getStatus());
        cplex.output().println("Solution value  = " + cplex.getObjValue());

        double[] val = cplex.getValues(x);
        int ncols = cplex.getNcols();
        for (int j = 0; j < ncols; ++j)
          cplex.output().println("Column: " + j + " Value = " + val[j]);
      }
      cplex.end();
    }
    catch (IloException e) {
      System.err.println("Concert exception '" + e + "' caught");
    }
  }
}