design_patterns

All those are learning from derek's design_patterns video serials youtube channel

1. strategy pattern:

   • a list of similar algorithms, implement every one in a seperate class
   • attach one of the implemented class's instance to our running class
   • may need dynamic change (not necessary)

   example:

   class Test {
       private Strategy strategy;
       public Test(Strategy strategy) {
           this.strategy = strategy;
       }    
       
       public void trySpark() {
           System.out.println(strategy.spark());
       }
   
       public void setStrategy(Strategy strategy) {
           # changing working behavior dynamicly       
           this.strategy = strategy;
       }
   }
   
   Interface Strategy {
       public string spark();
   }
   
   class DogStrategy implements Strategy {
       @override
       public string spark() {
           return "Wang Wang";
       }
   }
   
   class CatStrategy implements Strategy {
       @override
       public string spark() {
           return "Miao Miao";
       }
   }