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This article mainly introduces the relevant knowledge of how to achieve the strategic pattern in Android, the content is detailed and easy to understand, the operation is simple and fast, and has a certain reference value. I believe you will gain something after reading this Android article on how to achieve the strategic pattern. Let's take a look at it.

Strategy mode

The effect of a function, there are different algorithms and strategies, according to different choices to choose different results.

To put it simply, as long as you have written a program, you have used strategic mode. Don't say you haven't used it. Haven't you used if-else (switch)?

If-else is actually the embodiment of a strategic model, dealing with different results according to different choices.

problem

If all the methods are handled with if-else (switch), there is no problem in terms of function, but in terms of maintenance and use at the code level, too much if-else will make the class too large, difficult to read and difficult to modify.

Solve the problem

Using the policy pattern, define a unified interface, each different function (if-else) implementation interface to do a specific class, external calls to specific classes to achieve different results.

Working with scen

There are different solutions to the same problem

The judgment processing result of a class with multiple if-else

When encapsulating SDK, the upper layer returns the result. The caller cares about the result, not the implementation process.

Adapter for animated TimeInterpolator,ListView included in the Android source code

Code implementation

There is a commodity for sale. In the process of selling, different users should be given different prices (half price, 20% discount, 30% discount, etc.). Under the premise of knowing the user, how to give the price directly?

(1) implementation of price interface

Public interface PriceStrategy {int setPrice (int price);}

(2) implement specific price categories

30% discount:

Public class seventPriceStrategy implements PriceStrategy {@ Override public Double setPrice (int price) {return 0.7 * price;}}

50% discount:

Public class HalfPriceStrategy implements PriceStrategy {@ Override public Double setPrice (int price) {return 0.5 * price;}}

(3) Price algorithm management class

Public class PriceAlgorithm {private PriceStrategy priceStrategy; public PriceStrategy getPriceStrategy () {return priceStrategy;} public void setPriceStrategy (PriceStrategy priceStrategy) {this.priceStrategy = priceStrategy;} public Double getPrice (int price) {if {return priceStrategy.setPrice (price);} return null;}}

Pass in the specific implementation class to get the return interface

(4) method of calling

PriceAlgorithm priceAlgorithm = new PriceAlgorithm (); priceAlgorithm.setPriceStrategy (new HalfPriceStrategy ()); System.out.print ("\ n" + "1 yuan" + "50% discount price:" + String.valueOf (priceAlgorithm.getPrice (1); PriceAlgorithm priceAlgorithm2 = new PriceAlgorithm (); priceAlgorithm2.setPriceStrategy (new seventPriceStrategy ()); System.out.print ("\ n" + "2 yuan" + "30% discount price:" + String.valueOf (priceAlgorithm2.getPrice (2)

(5) display the results

Price after 50% discount of 1 yuan: 0.5

Price after 2 yuan 30% discount: 1.4

This is the end of the article on "how to implement strategic patterns in Android". Thank you for reading! I believe you all have a certain understanding of the knowledge of "how to implement the strategic model in Android". If you want to learn more, you are welcome to follow the industry information channel.

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