60 lines
1.6 KiB
Java
60 lines
1.6 KiB
Java
//: typeinfo/NullRobot.java
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// Using a dynamic proxy to create a Null Object.
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import java.lang.reflect.*;
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import java.util.*;
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import net.mindview.util.*;
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class NullRobotProxyHandler implements InvocationHandler {
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private String nullName;
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private Robot proxied = new NRobot();
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NullRobotProxyHandler(Class<? extends Robot> type) {
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nullName = type.getSimpleName() + " NullRobot";
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}
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private class NRobot implements Null, Robot {
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@Override
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public String name() { return nullName; }
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@Override
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public String model() { return nullName; }
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@Override
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public List<Operation> operations() {
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return Collections.emptyList();
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}
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}
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@Override
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public Object
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invoke(Object proxy, Method method, Object[] args)
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throws Throwable {
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return method.invoke(proxied, args);
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}
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}
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public class NullRobot {
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public static Robot
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newNullRobot(Class<? extends Robot> type) {
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return (Robot)Proxy.newProxyInstance(
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NullRobot.class.getClassLoader(),
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new Class[]{ Null.class, Robot.class },
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new NullRobotProxyHandler(type));
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}
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public static void main(String[] args) {
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Robot[] bots = {
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new SnowRemovalRobot("SnowBee"),
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newNullRobot(SnowRemovalRobot.class)
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};
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for(Robot bot : bots)
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Robot.Test.test(bot);
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}
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} /* Output:
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Robot name: SnowBee
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Robot model: SnowBot Series 11
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SnowBee can shovel snow
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SnowBee shoveling snow
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SnowBee can chip ice
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SnowBee chipping ice
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SnowBee can clear the roof
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SnowBee clearing roof
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[Null Robot]
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Robot name: SnowRemovalRobot NullRobot
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Robot model: SnowRemovalRobot NullRobot
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*///:~
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