1 #include <iostream>
 2
 3 using namespace std;
 4
 5 //Suppose the position is 1 when strategy is Gnss ,and 2 when strategy is slam
 6 class LocateStrategy{
 7 public:
 8     LocateStrategy(){}
 9     ~LocateStrategy(){}
10     virtual int locateAlgorithm()=0;
11 };
12
13 class StrategyGnss:public LocateStrategy
14 {
15 public:
16     StrategyGnss() {}
17     ~StrategyGnss() {}
18     int locateAlgorithm(){
19         cout << "Locate By GNSS" << endl;
20         return 1;
21     }
22 };
23
24 class StrategySlam:public LocateStrategy
25 {
26 public:
27     StrategySlam() {}
28     ~StrategySlam() {}
29     int locateAlgorithm(){
30         cout << "Locate By SLAM" << endl;
31         return 2;
32     }
33 };
34
35 class Context
36 {
37 public:
38     Context(LocateStrategy* strategy) {
39         _strategy = strategy;
40     }
41     ~Context(){
42         delete _strategy;
43     }
44     int locateCalculate(){
45        return this->_strategy->locateAlgorithm();
46     }
47 private:
48     LocateStrategy* _strategy;
49 };
50
51 int main()
52 {
53     LocateStrategy *pStrategy = new StrategyGnss();
54     Context *pCon = new Context(pStrategy);
55     cout <<pCon->locateCalculate() << endl;
56
57     //Strategy Replacement
58     pStrategy = new StrategySlam();
59     pCon = new Context(pStrategy);
60     cout <<pCon->locateCalculate() << endl;
61 }

 1 public interface ILocateStrategy {
 2     int locateAlgorithm();
 3 }
 4
 5 public class StrategyGnss implements ILocateStrategy{
 6     public int locateAlgorithm() {
 7         System.out.println("locate calculate by Gnss");
 8         return 1;
 9     }
10 }
11
12 public class StrategySlam implements ILocateStrategy {
13     public int locateAlgorithm() {
14         System.out.println("locate calculate by Slam");
15         return 2;
16     }
17 }
18
19 public class Context {
20     private ILocateStrategy strategy;
21     public Context(ILocateStrategy strategy){
22         this.strategy = strategy;
23     }
24     public int getPosition(){
25         return  strategy.locateAlgorithm();
26     }
27 }
28
29 public class Main {
30     public static void main(String[] args){
31         Context context = new Context(new StrategyGnss());
32         System.out.println(context.getPosition());
33         context = new Context(new StrategySlam());
34         System.out.println(context.getPosition());
35     }
36 }