Concert Technology for Java Users

Here is a Java program using ILOG Concert Technology to solve the example model. An expanded version of this example is discussed in detail in Chapter 4, Concert Technology for Java Users.

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.out().println("Solution status = " + cplex.getStatus());
        cplex.out().println("Solution value  = " + cplex.getObjValue());

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