60 lines
1.4 KiB
Java
60 lines
1.4 KiB
Java
// functional/Strategize.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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interface Strategy {
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String approach(String msg);
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}
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class Soft implements Strategy {
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@Override
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public String approach(String msg) {
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return msg.toLowerCase() + "?";
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}
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}
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class Unrelated {
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static String twice(String msg) {
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return msg + " " + msg;
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}
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}
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public class Strategize {
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Strategy strategy;
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String msg;
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Strategize(String msg) {
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strategy = new Soft(); // [1]
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this.msg = msg;
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}
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void communicate() {
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System.out.println(strategy.approach(msg));
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}
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void changeStrategy(Strategy strategy) {
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this.strategy = strategy;
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}
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public static void main(String[] args) {
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Strategy[] strategies = {
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new Strategy() { // [2]
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public String approach(String msg) {
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return msg.toUpperCase() + "!";
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}
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},
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msg -> msg.substring(0, 5), // [3]
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Unrelated::twice // [4]
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};
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Strategize s = new Strategize("Hello there");
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s.communicate();
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for(Strategy newStrategy : strategies) {
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s.changeStrategy(newStrategy); // [5]
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s.communicate(); // [6]
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}
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}
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}
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/* Output:
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hello there?
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HELLO THERE!
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Hello
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Hello there Hello there
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*/
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