61 lines
1.4 KiB
Java
61 lines
1.4 KiB
Java
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//: patterns/strategy/StrategyPattern.java
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// <20>2015 MindView LLC: see Copyright.txt
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package patterns.strategy;
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import java.util.function.*;
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import static com.mindviewinc.util.PrintArray.*;
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// The common strategy base type:
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class FindMinima {
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Function<double[], double[]> algorithm;
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}
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// The various strategies:
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class LeastSquares extends FindMinima {
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LeastSquares() {
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// Line is a sequence of points (Dummy data):
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algorithm = (line) -> new double[] { 1.1, 2.2 };
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}
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}
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class Perturbation extends FindMinima {
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Perturbation() {
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algorithm = (line) -> new double[] { 3.3, 4.4 };
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}
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}
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class Bisection extends FindMinima {
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Bisection() {
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algorithm = (line) -> new double[] { 5.5, 6.6 };
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}
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}
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// The "Context" controls the strategy:
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class MinimaSolver {
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private FindMinima strategy;
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public MinimaSolver(FindMinima strat) {
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strategy = strat;
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}
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double[] minima(double[] line) {
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return strategy.algorithm.apply(line);
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}
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void changeAlgorithm(FindMinima newAlgorithm) {
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strategy = newAlgorithm;
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}
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}
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public class StrategyPattern {
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public static void main(String args[]) {
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MinimaSolver solver =
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new MinimaSolver(new LeastSquares());
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double[] line = {
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1.0, 2.0, 1.0, 2.0, -1.0,
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3.0, 4.0, 5.0, 4.0 };
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printArray(solver.minima(line));
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solver.changeAlgorithm(new Bisection());
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printArray(solver.minima(line));
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}
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} /* Output:
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1.1, 2.2
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5.5, 6.6
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*///:~
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