java.util.concurrent.atomic.AtomicBoolean;java.util.concurrent.atomic.AtomicInteger;java.util.concurrent.atomic.AtomicLong;java.util.concurrent.atomic.AtomicReference;

package test.java;import java.util.concurrent.CountDownLatch;import java.util.concurrent.atomic.AtomicInteger;import org.junit.Assert;import org.junit.Before;import org.junit.Test;/** * 測試AtomicInteger與普通int值在多線程下的遞增操作 */public class TestAtomic { // 原子Integer遞增對象 public static AtomicInteger counter_integer;// = new AtomicInteger(0); // 一個int類型的變量 public static int count_int = 0; @Before public void setUp() { // 所有測試開始之前執行初始設置工作 counter_integer = new AtomicInteger(0); } @Test public void testAtomic() throws InterruptedException { // 創建的線程數量 int threadCount = 100; // 其他附屬線程內部循環多少次 int loopCount = 10000600; // 控制附屬線程的輔助對象;(其他await的線程先等著主線程喊開始) CountDownLatch latch_1 = new CountDownLatch(1); // 控制主線程的輔助對象;(主線程等著所有附屬線程都運行完畢再繼續) CountDownLatch latch_n = new CountDownLatch(threadCount); // 創建并啟動其他附屬線程 for (int i = 0; i < threadCount; i++) {  Thread thread = new AtomicIntegerThread(latch_1, latch_n, loopCount);  thread.start(); } long startNano = System.nanoTime(); // 讓其他等待的線程統一開始 latch_1.countDown(); // 等待其他線程執行完 latch_n.await(); // long endNano = System.nanoTime(); int sum = counter_integer.get(); // Assert.assertEquals("sum 不等于 threadCount * loopCount,測試失敗",  sum, threadCount * loopCount); System.out.println("--------testAtomic(); 預期兩者相等------------"); System.out.println("耗時: " + ((endNano - startNano) / (1000 * 1000)) + "ms"); System.out.println("threadCount = " + (threadCount) + ";"); System.out.println("loopCount = " + (loopCount) + ";"); System.out.println("sum = " + (sum) + ";"); } @Test public void testIntAdd() throws InterruptedException { // 創建的線程數量 int threadCount = 100; // 其他附屬線程內部循環多少次 int loopCount = 10000600; // 控制附屬線程的輔助對象;(其他await的線程先等著主線程喊開始) CountDownLatch latch_1 = new CountDownLatch(1); // 控制主線程的輔助對象;(主線程等著所有附屬線程都運行完畢再繼續) CountDownLatch latch_n = new CountDownLatch(threadCount); // 創建并啟動其他附屬線程 for (int i = 0; i < threadCount; i++) {  Thread thread = new IntegerThread(latch_1, latch_n, loopCount);  thread.start(); } long startNano = System.nanoTime(); // 讓其他等待的線程統一開始 latch_1.countDown(); // 等待其他線程執行完 latch_n.await(); // long endNano = System.nanoTime(); int sum = count_int; // Assert.assertNotEquals(  "sum 等于 threadCount * loopCount,testIntAdd()測試失敗",   sum, threadCount * loopCount); System.out.println("-------testIntAdd(); 預期兩者不相等---------"); System.out.println("耗時: " + ((endNano - startNano) / (1000*1000))+ "ms"); System.out.println("threadCount = " + (threadCount) + ";"); System.out.println("loopCount = " + (loopCount) + ";"); System.out.println("sum = " + (sum) + ";"); } // 線程 class AtomicIntegerThread extends Thread { private CountDownLatch latch = null; private CountDownLatch latchdown = null; private int loopCount; public AtomicIntegerThread(CountDownLatch latch,  CountDownLatch latchdown, int loopCount) {  this.latch = latch;  this.latchdown = latchdown;  this.loopCount = loopCount; } @Override public void run() {  // 等待信號同步  try {  this.latch.await();  } catch (InterruptedException e) {  e.printStackTrace();  }  //  for (int i = 0; i < loopCount; i++) {  counter_integer.getAndIncrement();  }  // 通知遞減1次  latchdown.countDown(); } } // 線程 class IntegerThread extends Thread { private CountDownLatch latch = null; private CountDownLatch latchdown = null; private int loopCount; public IntegerThread(CountDownLatch latch,   CountDownLatch latchdown, int loopCount) {  this.latch = latch;  this.latchdown = latchdown;  this.loopCount = loopCount; } @Override public void run() {  // 等待信號同步  try {  this.latch.await();  } catch (InterruptedException e) {  e.printStackTrace();  }  //  for (int i = 0; i < loopCount; i++) {  count_int++;  }  // 通知遞減1次  latchdown.countDown(); } }}

--------------testAtomic(); 預期兩者相等-------------------耗時: 85366msthreadCount = 100;loopCount = 10000600;sum = 1000060000;--------------testIntAdd(); 預期兩者不相等-------------------耗時: 1406msthreadCount = 100;loopCount = 10000600;sum = 119428988;