68 lines
1.8 KiB
Java
68 lines
1.8 KiB
Java
// patterns/chain/ChainOfResponsibility.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// {java patterns.chain.ChainOfResponsibility}
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package patterns.chain;
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import java.util.*;
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import java.util.function.*;
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interface Algorithm {
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Result algorithm(List<Double> line);
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}
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class FindMinima {
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public static Result test(
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boolean success, String id, double d1, double d2) {
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System.out.println(id);
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if(success) // Actual test/calculation here
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return new Result(Arrays.asList(d1, d2));
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else // Try the next one in the chain:
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return Result.fail;
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}
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public static Result leastSquares(List<Double> line) {
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return test(false, "LeastSquares", 1.1, 2.2);
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}
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public static Result perturbation(List<Double> line) {
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return test(false, "Perturbation", 3.3, 4.4);
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}
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public static Result bisection(List<Double> line) {
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return test(true, "Bisection", 5.5, 6.6);
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}
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static List<Function<List<Double>, Result>>
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algorithms = Arrays.asList(
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FindMinima::leastSquares,
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FindMinima::perturbation,
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FindMinima::bisection
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);
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public static Result minima(List<Double> line) {
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for(Function<List<Double>, Result> alg :
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algorithms) {
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Result result = alg.apply(line);
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if(result.success)
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return result;
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}
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return Result.fail;
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}
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}
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public class ChainOfResponsibility {
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public static void main(String[] args) {
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FindMinima solver = new FindMinima();
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List<Double> line = Arrays.asList(
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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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Result result = solver.minima(line);
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if(result.success)
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System.out.println(result.line);
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else
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System.out.println("No algorithm found");
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}
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}
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/* Output:
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LeastSquares
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Perturbation
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Bisection
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[5.5, 6.6]
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*/
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