73 lines
2.1 KiB
Java
73 lines
2.1 KiB
Java
//: generics/Apply.java
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// ©2015 MindView LLC: see Copyright.txt
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// {main: ApplyTest}
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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 Apply {
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public static <T, S extends Iterable<? extends T>>
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void apply(S seq, Method f, Object... args) {
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try {
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for(T t: seq)
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f.invoke(t, args);
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} catch(IllegalAccessException |
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IllegalArgumentException |
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InvocationTargetException e) {
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// Failures are programmer errors
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throw new RuntimeException(e);
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}
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}
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}
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class Shape {
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public void rotate() { print(this + " rotate"); }
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public void resize(int newSize) {
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print(this + " resize " + newSize);
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}
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}
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class Square extends Shape {}
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class FilledList<T> extends ArrayList<T> {
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public FilledList(Class<? extends T> type, int size) {
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try {
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for(int i = 0; i < size; i++)
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// Assumes default constructor:
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add(type.newInstance());
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} catch(InstantiationException |
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IllegalAccessException e) {
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throw new RuntimeException(e);
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}
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}
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}
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class ApplyTest {
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public static void main(String[] args) throws Exception {
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List<Shape> shapes = new ArrayList<>();
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for(int i = 0; i < 10; i++)
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shapes.add(new Shape());
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Apply.apply(shapes, Shape.class.getMethod("rotate"));
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Apply.apply(shapes,
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Shape.class.getMethod("resize", int.class), 5);
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List<Square> squares = new ArrayList<>();
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for(int i = 0; i < 10; i++)
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squares.add(new Square());
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Apply.apply(squares, Shape.class.getMethod("rotate"));
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Apply.apply(squares,
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Shape.class.getMethod("resize", int.class), 5);
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Apply.apply(new FilledList<>(Shape.class, 10),
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Shape.class.getMethod("rotate"));
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Apply.apply(new FilledList<>(Square.class, 10),
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Shape.class.getMethod("rotate"));
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SimpleQueue<Shape> shapeQ = new SimpleQueue<>();
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for(int i = 0; i < 5; i++) {
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shapeQ.add(new Shape());
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shapeQ.add(new Square());
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}
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Apply.apply(shapeQ, Shape.class.getMethod("rotate"));
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}
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} /* (Execute to see output) *///:~
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