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improve getSolverEnum on java

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lperron@google.com
2011-12-08 16:47:57 +00:00
parent 05fbc835c8
commit 09487025a8
3 changed files with 138 additions and 111 deletions
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93
com/google/ortools/linearsolver/samples/IntegerProgramming.java
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@@ -29,50 +29,63 @@ public class IntegerProgramming {
}
private static void runIntegerProgrammingExample(String solverType) {
private static MPSolver createSolver (String solverType) {
try {
MPSolver solver = new MPSolver("IntegerProgrammingExample",
MPSolver.getSolverEnum(solverType));
double infinity = solver.infinity();
// x1 and x2 are integer non-negative variables.
MPVariable x1 = solver.makeIntVar(0.0, infinity, "x1");
MPVariable x2 = solver.makeIntVar(0.0, infinity, "x2");
// Minimize x1 + 2 * x2.
solver.setObjectiveCoefficient(x1, 1);
solver.setObjectiveCoefficient(x2, 2);
// 2 * x2 + 3 * x1 >= 17.
MPConstraint ct = solver.makeConstraint(17, infinity);
ct.setCoefficient(x1, 3);
ct.setCoefficient(x2, 2);
int resultStatus = solver.solve();
// Check that the problem has an optimal solution.
if (resultStatus != MPSolver.OPTIMAL) {
System.err.println("The problem does not have an optimal solution!");
return;
}
System.out.println("Problem solved in " + solver.wallTime() +
" milliseconds");
// The objective value of the solution.
System.out.println("Optimal objective value = " + solver.objectiveValue());
// The value of each variable in the solution.
System.out.println("x1 = " + x1.solutionValue());
System.out.println("x2 = " + x2.solutionValue());
System.out.println("Advanced usage:");
System.out.println("Problem solved in " + solver.nodes() +
" branch-and-bound nodes");
} catch (java.lang.Exception exc) {
System.out.println("- Solver not supported.");
return new MPSolver("IntegerProgrammingExample",
MPSolver.getSolverEnum(solverType));
} catch (java.lang.ClassNotFoundException e) {
throw new Error(e);
} catch (java.lang.NoSuchFieldException e) {
return null;
} catch (java.lang.IllegalAccessException e) {
throw new Error(e);
}
}
private static void runIntegerProgrammingExample(String solverType) {
MPSolver solver = createSolver(solverType);
if (solver == null) {
System.out.println("Could not create solver " + solverType);
return;
}
double infinity = solver.infinity();
// x1 and x2 are integer non-negative variables.
MPVariable x1 = solver.makeIntVar(0.0, infinity, "x1");
MPVariable x2 = solver.makeIntVar(0.0, infinity, "x2");
// Minimize x1 + 2 * x2.
solver.setObjectiveCoefficient(x1, 1);
solver.setObjectiveCoefficient(x2, 2);
// 2 * x2 + 3 * x1 >= 17.
MPConstraint ct = solver.makeConstraint(17, infinity);
ct.setCoefficient(x1, 3);
ct.setCoefficient(x2, 2);
int resultStatus = solver.solve();
// Check that the problem has an optimal solution.
if (resultStatus != MPSolver.OPTIMAL) {
System.err.println("The problem does not have an optimal solution!");
return;
}
System.out.println("Problem solved in " + solver.wallTime() +
" milliseconds");
// The objective value of the solution.
System.out.println("Optimal objective value = " +
solver.objectiveValue());
// The value of each variable in the solution.
System.out.println("x1 = " + x1.solutionValue());
System.out.println("x2 = " + x2.solutionValue());
System.out.println("Advanced usage:");
System.out.println("Problem solved in " + solver.nodes() +
" branch-and-bound nodes");
}
public static void main(String[] args) throws Exception {
System.out.println("---- Integer programming example with GLPK ----");