66 lines
1.6 KiB
Java
66 lines
1.6 KiB
Java
//: patterns/strategy/StrategyPattern.java
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package patterns.strategy;
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// The strategy interface:
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interface FindMinima {
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// Line is a sequence of points:
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double[] algorithm(double[] line);
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}
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// The various strategies:
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class LeastSquares implements FindMinima {
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@Override
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public double[] algorithm(double[] line) {
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return new double[] { 1.1, 2.2 }; // Dummy
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}
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}
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class Perturbation implements FindMinima {
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@Override
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public double[] algorithm(double[] line) {
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return new double[] { 3.3, 4.4 }; // Dummy
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}
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}
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class Bisection implements FindMinima {
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@Override
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public double[] algorithm(double[] line) {
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return new double[] { 5.5, 6.6 }; // Dummy
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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(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 printArray(double[] array) {
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for(int i = 0; i < array.length; i++) {
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System.out.print(array[i]);
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if(i != array.length -1)
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System.out.print(", ");
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}
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System.out.println();
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}
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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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} ///:~
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