學習網站： https://www.youtube.com/watch?v=9liopGtCF6w public class Counter { public static int count = 0 ; // 一個公開靜態屬性 An public static attribute public static void main ( String [] args ) throws Exception { // 計算程式執行的時間 Trace running time long startTime = System . currentTimeMillis (); /* Test an easy method to increase count 2 billions times 測試一個簡單的方法 , 把數字累加 20 億次 */ for ( int i = 0 ; i 200000000 ; i ++) { Counter . count ++; } long endTime = System . currentTimeMillis (); System . out . println ( " 單一程序運算時間 : " +( endTime - startTime )+ " mSecs" ); Counter . count = 0 ; startTime = System . currentTimeMillis (); /* Compute in parallel by Thread 使用執行續 , 讓工作同時分散進行 We have to design a class implementing Runnable interface and instantiate it. 必須準備一個實作 Runnable 介面的類別 , 並產生物件實體 Create thread by object instance implementing Runnable interface 利用實作 Runnable 介面的物件 , 建立執行緒 */ Thread t1 = new Thread ( new Worker ( 100000000 )); Thread t2 = new Thread ( new Worker ( 100000000 )); t1 . start (); // 啟動執行緒工作 Start thread t2 . start (); t1 . join (); // 等待執行緒工作完成 Wait thread to finish t2 . join (); endTime = System . currentTimeMillis (); System . out . println ( " 雙執行緒運算時間 : " +( endTime - startTime )+ " mSecs" ); } } public class Worker implements Runnable { private int times ; int count ; // 物件建構子 public Worker ( int times ) { this . times = times ; } // 實作 Runnable 介面 Implement Runnable interface public void run () { count = 0 ; for ( int i = 0 ; i this . times ; i ++) { count ++; } } } 驗證結果： 單一程序運算時間 : 2393 mSecs 雙執行緒運算時間 : 2239 mSecs
標籤: java
