package test;

import java.util.LinkedList;

public class Test {

    static int i = 0;

    private interface Handler {
        public void handle(Object o);
    }
    private static class SuperHandler implements Handler {
        public void handle(Object o) { i += 1; }
    }
    private static class NoSuperHandler implements Handler {
        public void handle(Object o) { i += 1; }
    }
    private static class LulSuperHandler implements Handler {
        public void handle(Object o) { i += 1; }
    }
    private static class LilSuperHandler implements Handler {
        public void handle(Object o) { i += 1; }
    }
    private static class LolSuperHandler implements Handler {
        public void handle(Object o) { i += 1; }
    }
    private static class LalSuperHandler implements Handler {
        public void handle(Object o) { i += 1; }
    }
    private static class LylSuperHandler implements Handler {
        public void handle(Object o) { i += 1; }
    }
    private static class LzlSuperHandler implements Handler {
        public void handle(Object o) { i += 1; }
    }

    public static void main(String[] args) {
        LinkedList<Handler> ll = new LinkedList<Handler>();
        for(int j = 0; j < 100; j++) {
            if((j % 8) == 0) ll.add(new SuperHandler());
            if((j % 8) == 1) ll.add(new NoSuperHandler());
            if((j % 8) == 2) ll.add(new LulSuperHandler());
            if((j % 8) == 3) ll.add(new LilSuperHandler());
            if((j % 8) == 4) ll.add(new LolSuperHandler());
            if((j % 8) == 5) ll.add(new LalSuperHandler());
            if((j % 8) == 6) ll.add(new LylSuperHandler());
            if((j % 8) == 7) ll.add(new LzlSuperHandler());
        }
        long begin = System.currentTimeMillis();
        for(int j = 0; j < 1000000; j++) for(Handler h: ll) h.handle(null);
        System.out.println("time in ms: " + (System.currentTimeMillis() - begin));
        System.out.println("i: " + i);
    }
}

事实是,如果LinkedList只包含一种Handler,例如SuperHandler,则执行时间小于它们是2,3等不同种类的Handler.每次我在列表中添加一种新的Handler时,性能会下降.

例如,当我只改变这部分时,我获得了比上面更好的表现：

for(int j = 0; j < 100; j++) {
    if((j % 2) == 0) ll.add(new SuperHandler());
    if((j % 2) == 1) ll.add(new NoSuperHandler());
}

这里有特殊的优化操作吗？ JAVA架构中的性能会降低多少？我的测试是错误的,因为未使用的Handler被编译器“删除”或“隐藏”了吗？
(我正在使用Linux Ubuntu – 来自Oracle的JAVA 1.7)