The statement "defines a family of functionality, encapsulates each one, and makes them interchangeable" describes a Strategy Pattern.
The alternative name for the Strategy Pattern is Policy.
The benefits are:
- It runs concurrently with subclassification.
- By defining each behavior in its own class, conditional statements are unnecessary.
- It facilitates the incorporation and extension of novel behavior without requiring an application redesign.
The usages are:
- When the only distinction between multiple classes is their behavior, such as Servlet API.
- It is utilized when various iterations of an algorithm are required.
Source code of ArithmaticAlgorithm.java
package com.t4b.test.java.dp.bp.sp;
interface ArithmaticAlgorithm {
public int calculate(int num1, int num2);
}
Source code of ArithmaticContext.java
package com.t4b.test.java.dp.bp.sp;
class ArithmaticContext {
private ArithmaticAlgorithm algorithm;
public ArithmaticContext(ArithmaticAlgorithm strategy) {
this.algorithm = strategy;
}
public int execute(int num1, int num2) {
return algorithm.calculate(num1, num2);
}
}
Source code of ArithmaticAdd.java
package com.t4b.test.java.dp.bp.sp;
class ArithmaticAdd implements ArithmaticAlgorithm {
@Override
public int calculate(int num1, int num2) {
return num1 + num2;
}
}
Source code of ArithmaticMul.java
package com.t4b.test.java.dp.bp.sp;
class ArithmaticMul implements ArithmaticAlgorithm {
@Override
public int calculate(int num1, int num2) {
return num1 * num2;
}
}
Source code of ArithmaticSub.java
package com.t4b.test.java.dp.bp.sp;
class ArithmaticSub implements ArithmaticAlgorithm {
@Override
public int calculate(int num1, int num2) {
return num1 - num2;
}
}
Source code of TestMain.java
package com.t4b.test.java.dp.bp.sp;
public class TestMain {
public static void main(String[] args) {
int x = 10, y = 5;
ArithmaticContext context = new ArithmaticContext(new ArithmaticAdd());
System.out.println(x + " + " + y + " = " + context.execute(x, y));
context = new ArithmaticContext(new ArithmaticSub());
System.out.println(x + " - " + y + " = " + context.execute(x, y));
context = new ArithmaticContext(new ArithmaticMul());
System.out.println(x + " * " + y + " = " + context.execute(x, y));
}
}
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