物件導向程式 低耦合、高內聚 - 耦合編 (Coupling)

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// 壞例1 :
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public void run(){
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    takeAction(1);
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}
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public void takeAction(int key) {
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    switch (key) {
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        case 1:
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            System.out.println("ONE RECEIVED");
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            break;
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        case 2:
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            System.out.println("TWO RECEIVED");
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            break;
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    }
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}
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// 優解1-1 :
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public void run(){
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    Printable printable = new PrinterOne();
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    takeAction(printable);
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}
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public void takeAction(Printable printable){
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    printable.print();
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}
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public interface Printable{
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    void print();
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}
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public class PrinterOne implements Printable{
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    @Override
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    public void print() {
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        System.out.println("ONE RECEIVED");
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    }
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}
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public class PrinterTwo implements Printable{
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    @Override
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    public void print() {
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        System.out.println("TWO RECEIVED");
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    }
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}
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// 優解1-2 :
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public static void main(String ... args){
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    new Printer().takeAction(1);
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}
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@CommandsMapFactory
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public class Printer {
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    private final CommandsMap map = CommandsMap.of(this);
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    public void takeAction(int key){
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        map.execute(key);
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    }
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    @Command(1)
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    void printOne() {
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        System.out.println("ONE RECEIVED");
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    }
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    @Command(2)
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    void printTwo() {
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        System.out.println("TWO RECEIVED");
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    }
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}
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//--------------------
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// 壞例2 :
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void updateView(boolean isError) {
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    if (isError) {
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        resultView.setVisible(true);
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        errorView.setVisible(false);
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        iconView.setImage(CROSS_MARK_IMAGE);
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    } else {
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        resultView.setVisible(false);
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        errorView.setVisible(true);
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        iconView.setImage(CHECk_MARK_IMAGE);
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    }
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}
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// 優解2 :
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void updateView(boolean isError) {
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    resultView.setVisible(isError);
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    errorView.setVisible(!isError);
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    iconView.setImage(getIconImage(isError));
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}
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Image getIconImage(boolean isError):  return (!isError) ? CHECk_MARK_IMAGE : CROSS_MARK_IMAGE

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// 壞例1 :
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public int sumValues(Calculator c){
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    int result = c.getFirstNumber() + c.getSecondNumber();
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    c.setResult(result);
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    return c.getResult();
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}
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// 優解1 :
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public int sumValues(Calculator c){
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 //其他過程由Calculator內部執行
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    c.sumAndUpdateResult();
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    return c.getResult();
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}
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//--------------------
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// 壞例2 :
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public int callCalculator(Calculator c) {
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    c.setParameter(42);
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    c.prepare();
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    c.calculate();
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    c.tearDown();
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    return c.getResult();
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}
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// 優解2 :
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public int callCalculator(Calculator c) {
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    //其他過程由Calculator內部執行
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    c.setAndCalculateResult(42);
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    return c.getResult();
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}