31 lines
1.2 KiB
Java
31 lines
1.2 KiB
Java
//: containers/SpringDetector.java
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// What will the weather be?
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import java.lang.reflect.*;
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import java.util.*;
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import static net.mindview.util.Print.*;
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public class SpringDetector {
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// Uses a Groundhog or class derived from Groundhog:
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public static <T extends Groundhog>
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void detectSpring(Class<T> type) throws Exception {
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Constructor<T> ghog = type.getConstructor(int.class);
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Map<Groundhog,Prediction> map = new HashMap<>();
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for(int i = 0; i < 10; i++)
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map.put(ghog.newInstance(i), new Prediction());
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print("map = " + map);
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Groundhog gh = ghog.newInstance(3);
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print("Looking up prediction for " + gh);
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if(map.containsKey(gh))
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print(map.get(gh));
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else
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print("Key not found: " + gh);
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}
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public static void main(String[] args) throws Exception {
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detectSpring(Groundhog.class);
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}
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} /* Output:
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map = {Groundhog #0=Six more weeks of Winter!, Groundhog #4=Six more weeks of Winter!, Groundhog #3=Early Spring!, Groundhog #8=Six more weeks of Winter!, Groundhog #2=Early Spring!, Groundhog #5=Early Spring!, Groundhog #9=Six more weeks of Winter!, Groundhog #7=Early Spring!, Groundhog #1=Six more weeks of Winter!, Groundhog #6=Early Spring!}
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Looking up prediction for Groundhog #3
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Key not found: Groundhog #3
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*///:~
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