标签：style blog color io os ar 使用 java for
接口Command：定义命令的执行操作
package common;
public interface Command {
// 运行方法
void run();
}
CommandRuntime 类:统计命令运行时间，使用命令模式
package common; public class CommandRuntime { private Command command; public CommandRuntime(Command command) { this.command = command; } public long runtime() { long start = System.currentTimeMillis(); command.run(); long end = System.currentTimeMillis(); return end-start; } }
CombinationCommand: 解决组合问题的命令， 采用类适配器模式：
package algorithm.problems; import algorithm.permutation.Combination; import common.Command; public class CombinationCommand extends Combination implements Command { public CombinationCommand(int n) { super(n); } public void run() { solution(); } }
CombinationRuntime: 测量组合问题的运行时间
package algorithm.problems;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import common.CommandRuntime;
public class CombinationRuntime {
public static void main(String[] args)
{
try {
BufferedWriter fileWriter = new BufferedWriter(new FileWriter("runtime.txt"));
fileWriter.write("runtime: ");
fileWriter.newLine();
for (int i=1; i < 30; i++) {
CommandRuntime comRuntime = new CommandRuntime(new CombinationCommand(i));
long runtime = comRuntime.runtime();
fileWriter.write( "n = " + i + " : " + runtime + " ms");
fileWriter.newLine();
}
System.out.println("over.");
fileWriter.close();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
}
另外一种使用反射机制实现的运行时间测量框架：
package common; import java.lang.reflect.Constructor; import java.lang.reflect.Method; public class RuntimeMeasurement { public RuntimeMeasurement(int maxsize) { this.maxsize = maxsize; time = new double[maxsize]; } // 问题最大规模: 以 10 的 size 次幂计 private int maxsize ; // 运行时间以 ms 计 private double[] time ; /** * measureTime : 对指定类型的对象调用指定参数列表的指定方法，并测量其运行时间 * @param type 指定对象类型，必须有一个 参数类型为 int 的公共构造器方法 * @param methodName 指定测试方法名称，要求是空参数列表 */ public void measureTime(Class<?> type, String methodName) { try { Constructor<?> con = type.getConstructor(int.class); Method testMethod = null; for (int i = 0; i < time.length; i++) { Object obj = con.newInstance(power10(i+1)); testMethod = type.getMethod(methodName, new Class<?>[]{}); long start = System.nanoTime(); testMethod.invoke(obj, new Object[] {}); long end = System.nanoTime(); time[i] = ((end - start) / (double)1000000) ; } } catch (Exception e) { e.printStackTrace(); System.out.println(e.getMessage()); } } /** * showTime : 显示已经测量获得的运行时间，在 measureTime 方法调用后调用该方法。 */ public void showTime() { for (int i=0; i < time.length; i++) { System.out.printf("n = %12d : " , power10(i+1)); System.out.printf("%12.3f\n", time[i]); } } private int power10(int n) { int result = 1; while (n > 0) { result *= 10; n--; } return result; } }
标签：style blog color io os ar 使用 java for
原文地址：http://www.cnblogs.com/lovesqcc/p/4038393.html
