StopwatchClient.java

package trial.yy.guava.client.base;

import com.google.common.base.Stopwatch;

import java.util.Random;

/**
 * com.google.common.base.Stopwatchを試すためのサンプル
 * User: yy
 * Date: 13/04/23
 * Time: 23:01
 */
public class StopWatchClient {

    public static void main(String[] args) {

        // Stopwatchを使わない場合の計測
        long start = System.currentTimeMillis();
        executeBusinessLogic();
        long end = System.currentTimeMillis();

        System.out.println("Execution time1: " + (end - start) + "ms");

        // Stopwatchを使うとこんな感じ
        Stopwatch stopwatch1 = new Stopwatch().start();
        executeBusinessLogic();
        stopwatch1.stop();

        System.out.println("Execution time2: " + stopwatch1);

        // 15.0からは コンストラクタの使用は非推奨になるかも
        // Stopwatch#createStarted or Stopwatch#createUnstartedを使うことになりそうです。

        // リセットすると0に戻る
        stopwatch1.reset();
        System.out.println("Execution time3: " + stopwatch1);

        // リセット後に再測定
        stopwatch1.start();
        executeBusinessLogic();
        stopwatch1.stop();

        System.out.println("Execution time4: " + stopwatch1);
    }

    /**
     * 何か業務処理の代わり
     */
    private static void executeBusinessLogic() {

        Random r = new Random();
        try {
            Thread.sleep(1000 * r.nextInt(4));
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }
}