java调用cplex求vrp问题，写出代码

下面是一个使用Cplex Java API求解VRP问题的简单代码示例：

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

public class VRPSolver {
    public static void main(String[] args) {
        try {
            // Define VRP problem data
            int numNodes = 10;
            int numVehicles = 3;
            double[] demand = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
            double[] x = {...}; // Node x coordinates
            double[] y = {...}; // Node y coordinates
            double[][] cost = {...}; // Distance matrix

            // Create Cplex model
            IloCplex cplex = new IloCplex();

            // Define decision variables
            IloIntVar[][] xVars = new IloIntVar[numNodes][numNodes];
            for (int i = 0; i < numNodes; i++) {
                for (int j = 0; j < numNodes; j++) {
                    xVars[i][j] = cplex.boolVar();
                }
            }
            IloIntVar[] uVars = new IloIntVar[numNodes];
            for (int i = 0; i < numNodes; i++) {
                uVars[i] = cplex.intVar(0, numVehicles);
            }

            // Define objective function
            IloLinearNumExpr obj = cplex.linearNumExpr();
            for (int i = 0; i < numNodes; i++) {
                for (int j = 0; j < numNodes; j++) {
                    obj.addTerm(cost[i][j], xVars[i][j]);
                }
            }
            cplex.addMinimize(obj);

            // Define constraints
            for (int i = 1; i < numNodes; i++) {
                IloLinearNumExpr expr = cplex.linearNumExpr();
                for (int j = 0; j < numNodes; j++) {
                    if (j != i) {
                        expr.addTerm(1.0, xVars[i][j]);
                    }
                }
                cplex.addEq(expr, 1.0);
            }
            for (int j = 1; j < numNodes; j++) {
                IloLinearNumExpr expr = cplex.linearNumExpr();
                for (int i = 0; i < numNodes; i++) {
                    if (i != j) {
                        expr.addTerm(1.0, xVars[i][j]);
                    }
                }
                cplex.addEq(expr, 1.0);
            }
            for (int i = 1; i < numNodes; i++) {
                for (int j = 1; j < numNodes; j++) {
                    if (i != j) {
                        IloLinearNumExpr expr = cplex.linearNumExpr();
                        expr.addTerm(1.0, uVars[i]);
                        expr.addTerm(-1.0, uVars[j]);
                        expr.addTerm(numNodes - 1.0, xVars[i][j]);
                        cplex.addLe(expr, numNodes - 2.0);
                    }
                }
            }
            for (int i = 1; i < numNodes; i++) {
                for (int j = 1; j < numNodes; j++) {
                    if (i != j) {
                        IloLinearNumExpr expr = cplex.linearNumExpr();
                        expr.addTerm(1.0, uVars[i]);
                        expr.addTerm(-1.0, uVars[j]);
                        expr.addTerm(numVehicles - 1.0, xVars[i][j]);
                        cplex.addGe(expr, 0.0);
                    }
                }
            }
            for (int i = 1; i < numNodes; i++) {
                for (int j = 1; j < numNodes; j++) {
                    if (i != j) {
                        IloLinearNumExpr expr = cplex.linearNumExpr();
                        expr.addTerm(1.0, uVars[i]);
                        expr.addTerm(-1.0, uVars[j]);
                        expr.addTerm(numVehicles - 1.0, xVars[i][j]);
                        cplex.addLe(expr, numVehicles - 2.0);
                    }
                }
            }

            // Solve VRP problem
            cplex.solve();

            // Print solution
            System.out.println("Solution status = " + cplex.getStatus());
            System.out.println("Objective value = " + cplex.getObjValue());
            for (int i = 0; i < numNodes; i++) {
                for (int j = 0; j < numNodes; j++) {
                    if (cplex.getValue(xVars[i][j]) > 0.5) {
                        System.out.println("Node " + i + " -> Node " + j);
                    }
                }
            }
        } catch (IloException e) {
            e.printStackTrace();
        }
    }
}

这个示例代码中使用了Cplex Java API来定义VRP问题的数学模型，并使用Cplex求解器来解决该问题。最后，将解决方案打印到控制台上。请注意，这个示例仅仅是一个简单的例子，实际的VRP问题可能要更加复杂。