1.使用多線程，模擬龜兔賽跑的場景。
按照以往的故事經驗，正確的故事邏輯順序當然是因為兔子不把烏龜放在眼里，松懈了最終輸了比賽。我的設定也是如此，假定烏龜每秒跑五米（是有點快但為了線程的運行速度來看還是寫快點）兔子的速度為每秒十米。但是兔子在跑到一半休息了一點五秒。
代碼如下：
package com.company; public class ThreadTest1 implements Runnable{ public void run(){ try { for(int i = 1;i<=100;i= i+5){ System.out.println("烏龜跑了"+i+"米"); Thread.sleep(1000); } } catch (InterruptedException e) { e.printStackTrace(); } } }
package com.company; public class ThreadTest2 implements Runnable{ public void run(){ try { for(int j = 1;j<=100;j=j+10){ System.out.println("兔子跑了"+j+"米"); Thread.sleep(1000); if(j==51){ Thread.sleep(15000); } } } catch (InterruptedException e) { e.printStackTrace(); } } }
package com.company; import javax.naming.Name; public class ThreadMain { static int a = 200; public static void main(String[] args) { ThreadTest1 threadTest1 = new ThreadTest1(); ThreadTest2 threadTest2 = new ThreadTest2(); Thread thread1 = new Thread(threadTest1); Thread thread2 = new Thread(threadTest2); thread1.start(); thread2.start(); } }
運行結果如下：
2、編寫一個有兩個線程的程序，第一個線程用來計算2～100000之間的素數的個數，第二個線程用來計算100000～200000之間的素數的個數，最后輸出結果。
思路：確定一個數為素數，他只能將本身和1整除，即聲明一個變量，寫兩個循壞嵌套，外面的循壞寫數的范圍，里面的循壞寫除數，每當數能將它的除數整除，變量加1，如果最后變量的值為2即確定此數為素數
package com.company; public class ThreadTest1 implements Runnable{ public void run(){ for(int i=2;i<=100000;i++){ int a = 0; for(int j=1;j<=i;j++){ if(i%j==0){ a++; } } if(a==2)//素數只能整除1和它本身，所以a=2時說明該數為素數 System.out.println("線程1========"+i); } } }
package com.company; public class ThreadTest2 implements Runnable{ public void run(){ for(int k=100000;k<=200000;k++){ int b = 0; for(int l=1;l<=k;l++){ if(k%l==0){ b++; } } if(b==2)//素數只能整除1和它本身，所以a=2時說明該數為素數 System.out.println("線程2======"+k); } } }
package com.company; import javax.naming.Name; public class ThreadMain { static int a = 200; public static void main(String[] args) { ThreadTest1 threadTest1 = new ThreadTest1(); ThreadTest2 threadTest2 = new ThreadTest2(); Thread thread1 = new Thread(threadTest1); Thread thread2 = new Thread(threadTest2); thread1.start(); thread2.start(); } }
結果片段：
3、使用多線程實現多個文件同步復制功能，並在控制台顯示復制的進度，進度以百分比表示。例如：把文件A復制到E盤某文件夾下，在控制台上顯示“XXX文件已復制10%”，“XXX文件已復制20%”……“XXX文件已復制100%”，“XXX復制完成！”
代碼如下，設置每次截取代碼長度除以文件總長度得到文件復制百分比，使用“DecimalFormat”類中的format方法將得到的數字乘以100並顯示為百分數。
1 package com.company; 2 3 import java.io.*; 4 import java.text.DecimalFormat; 5 6 public class CopyFile extends Thread { 7 8 public File oldFile; 9 public File newFile; 10 11 public CopyFile(String oldFile,String newFile) { 12 this.oldFile = new File(oldFile); 13 this.newFile = new File(newFile); 14 } 15 16 @Override 17 public void run() { 18 FileOutputStream fileOutputStream = null; 19 FileInputStream fileInputStream =null; 20 try { 21 fileOutputStream = new FileOutputStream(newFile); 22 fileInputStream = new FileInputStream(oldFile); 23 byte[] b = new byte[1024]; 24 int length = 0;//返回每次讀取的數據長度 25 long l = oldFile.length();//文件的長度 26 double temp = 0;// 27 DecimalFormat decimalFormat = new DecimalFormat("%"); 28 while ((length = fileInputStream.read(b))!=-1){ 29 fileOutputStream.write(b,0,length); 30 temp += length;//將每次讀到的數據進行累加 31 double d = temp/l; 32 int dd = (int) d; 33 if(dd%10==0){ 34 System.out.println("文件已經復制"+decimalFormat.format(d)); 35 } 36 } 37 System.out.println(oldFile.getName()+"復制完成"); 38 } catch (IOException e) { 39 e.printStackTrace(); 40 }finally { 41 try { 42 fileInputStream.close(); 43 fileOutputStream.close(); 44 } catch (IOException e) { 45 e.printStackTrace(); 46 } 47 } 48 49 } 50 }
package com.company; public class CopyTest { public static void main(String[] args) { CopyFile cf1 = new CopyFile("E:\\a.txt", "D:\\a.txt"); CopyFile cf2 = new CopyFile("E:\\b.txt", "D:\\b.txt"); CopyFile cf3 = new CopyFile("E:\\c.txt", "D:\\c.txt"); cf1.start(); cf2.start(); cf3.start(); } }
結果：
4、設計4個線程，其中兩個線程每次對j增加1，另外兩個線程對j每次減少1。考慮到線程的安全性寫出程序。
分別書寫四個線程對靜態變量j進行更改，在每個線程中都加入synchronized (ThreadTest.class)保證線程安全，在更改未做完其他線程無法運行
代碼如下
package com.company; public class ThreadTest1 implements Runnable { public void run() { try { for (int i = 0; i < 10000; i++) { synchronized (ThreadTest.class) { ThreadTest2.j++; System.out.println("線程1====="+ThreadTest2.j); Thread.sleep(100); }} } catch (InterruptedException e) { e.printStackTrace(); } } }
package com.company; public class ThreadTest2 implements Runnable{ public static int j=500; public static int k; public void run(){ try { for(int i=0;i<10000;i++){ synchronized (ThreadTest.class){ j++; System.out.println("線程2====="+j); Thread.sleep(100); } } } catch (InterruptedException e) { e.printStackTrace(); } } }
package com.company; public class ThreadTest3 implements Runnable { public void run() { try { for (int i = 0; i < 10000; i++) { synchronized (ThreadTest.class) { ThreadTest2.j--; System.out.println("線程3=====" + ThreadTest2.j); Thread.sleep(100); }} } catch (InterruptedException e) { e.printStackTrace(); } } }
package com.company; public class ThreadTest4 implements Runnable { public void run() { try { for (int i = 0; i < 10000; i++) { synchronized (ThreadTest.class) { ThreadTest2.j--; System.out.println("線程4=====" + ThreadTest2.j); Thread.sleep(100); }} } catch (InterruptedException e) { e.printStackTrace(); } } }
package com.company; import javax.naming.Name; public class ThreadMain { static int a = 200; public static void main(String[] args) { ThreadTest1 threadTest1 = new ThreadTest1(); ThreadTest2 threadTest2 = new ThreadTest2(); ThreadTest3 threadTest3 = new ThreadTest3(); ThreadTest4 threadTest4 = new ThreadTest4(); Thread thread1 = new Thread(threadTest1); Thread thread2 = new Thread(threadTest2); Thread thread3 = new Thread(threadTest3); Thread thread4 = new Thread(threadTest4); thread1.start(); thread2.start(); thread3.start(); thread4.start(); } }
截取部分結果如下：
