使用枚举的策略模式。 Java中需要一个简单的例子 [英] Strategy pattern using Enums. Need a simple example in Java

问题描述

我正在尝试了解java中的策略模式和枚举。我已经google了这个，并且发现了一些关于这个问题的文章，但是大多数文章似乎太复杂了，因为我的理解。任何人都可以提供一个简单的示例或其他链接，使用java显示使用枚举术语的策略模式？

感谢您提前。

解决方案

应该这样做：

 界面策略{
 
 int execute（int a，int b）; 
} 
 
枚举数学实现策略{
 
添加{
 
 @Override 
 public int execute（int a，int b）{
 return a + b; 
} 
}，
减去{
 
 @Override 
 public int execute（int a，int b）{
 return a  -  b ; 
} 
}，
乘以{
 
 @Override 
 public int execute（int a，int b）{
 return a * b ; 
} 
}; 
} 
  

这是一个重新实现的维基百科文章使用枚举的策略。

或稍长一点，但更明确的策略模式：

  public interface FailureStrategy {
 void fail（String message ）; 
} 
 
枚举失败实施FailureStrategy {
忽略{
 
 @Override 
 public void fail（String message）{
 //成功完成任务
} 
 
}，
 LogToConsole {
 
 @Override 
 public void fail（String message）{
 System.out .println（消息）; 
} 
 
}，
 ErrToConsole {
 
 @Override 
 public void fail（String message）{
 System.err .println（消息）; 
} 
 
}，
 RingAlarmBells {
 
 @Override 
 public void fail（String message）{
 // Left给学生
} 
 
}，
 SoundTheKlaxon {
 
 @Override 
 public void fail（String message）{
 // Left给学生
} 
 
}，
 EndTheWorld {
 
 @Override 
 public void fail（String message）{
 // Left给学生
} 
 
}; 
} 
 
 public class SomethingLethal {
 public FailureStrategy onFail = Failure.EndTheWorld; 
} 
 
 public class SomethingDangerous {
 public FailureStrategy onFail = Failure.RingAlarmBells; 
} 
 
 public class SomethingBenign {
 public FailureStrategy onFail = Failure.Ignore; 
} 
  

I'm trying to understand the strategy pattern and enums in java. I've googled this and have found a few articles on the subject, but most of them seemed too complex for my understanding. Could anyone provide a simple example or another link that demonstrates strategy pattern using enums in laymen terms using java?

Thanks you in advance.

解决方案

This should do:

interface Strategy {

    int execute(int a, int b);
}

enum Math implements Strategy {

    Add {

                @Override
                public int execute(int a, int b) {
                    return a + b;
                }
            },
    Subtract {

                @Override
                public int execute(int a, int b) {
                    return a - b;
                }
            },
    Multiply {

                @Override
                public int execute(int a, int b) {
                    return a * b;
                }
            };
}

It is a re-implementation of the Wikipedia article using enum for the strategies.

Or a little longer but more clearly a strategy pattern:

public interface FailureStrategy {
    void fail (String message);
}

enum Failure implements FailureStrategy {
    Ignore {

        @Override
        public void fail(String message) {
            // Do nothing on success.
        }

    },
    LogToConsole {

        @Override
        public void fail(String message) {
            System.out.println(message);
        }

    },
    ErrToConsole {

        @Override
        public void fail(String message) {
            System.err.println(message);
        }

    },
    RingAlarmBells {

        @Override
        public void fail(String message) {
            // Left to the student.
        }

    },
    SoundTheKlaxon {

        @Override
        public void fail(String message) {
            // Left to the student.
        }

    },
    EndTheWorld {

        @Override
        public void fail(String message) {
            // Left to the student.
        }

    };
}

public class SomethingLethal {
    public FailureStrategy onFail = Failure.EndTheWorld;
}

public class SomethingDangerous {
    public FailureStrategy onFail = Failure.RingAlarmBells;
}

public class SomethingBenign {
    public FailureStrategy onFail = Failure.Ignore;
}

这篇关于使用枚举的策略模式。 Java中需要一个简单的例子的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！