每个对象都有一内置锁
wait方法 释放对象锁(不占对象锁)
sleep方法不释放对象锁(占对象锁)
优秀写法 （下面写法可能有问题，synchronized (LOCK) 提到 while前面就好了）
1 class Info { 2 String printStr = "i think this is ok"; 3 int i = 0; 4 5 public void print() { 6 if (i < printStr.length()) { 7 System.out.println(Thread.currentThread().getName() + " print " 8 + printStr.charAt(i)); 9 i++; 10 } 11 } 12 } 13 14 public class main { 15 private static Object LOCK = new Object(); 16 static Info info = new Info(); // 互斥资源 17 static boolean flag = false; // false for a ,true for b 18 19 public static void main(String[] args) { 20 // 两个线程 交替打印字符串 21 Thread a = new Thread() { 22 public void run() { 23 while (info.i < info.printStr.length()) 24 synchronized (LOCK) { 25 { 26 if (false == flag) { 27 try { 28 LOCK.wait();// 在wait后的瞬间线程b得到锁 29 } catch (InterruptedException e) { 30 e.printStackTrace(); 31 } 32 } 33 flag = false; 34 info.print(); 35 LOCK.notify();// 在这里虽然唤醒了另一个线程b，但锁并没有释放 36 } 37 } 38 }; 39 }; 40 Thread b = new Thread() { 41 public void run() { 42 while (info.i < info.printStr.length()) 43 synchronized (LOCK) { 44 { 45 if (true == flag) { 46 try { 47 LOCK.wait();// 在wait后的瞬间线程b得到锁 48 } catch (InterruptedException e) { 49 e.printStackTrace(); 50 } 51 } 52 flag = true; 53 info.print(); 54 LOCK.notify();// 在这里虽然唤醒了另一个线程b，但锁并没有释放 55 } 56 } 57 }; 58 }; 59 a.start(); 60 b.start(); 61 } 62 63 }
代码1
1 package ThreadTest; 2 3 4 class Info 5 { 6 String printStr="i think this is ok"; 7 int i=0; 8 boolean flag=false; 9 public void print1() 10 { 11 synchronized(this) 12 { 13 if(flag==false) 14 { 15 try { 16 this.wait(); 17 } catch (InterruptedException e) { 18 e.printStackTrace(); 19 } 20 } 21 realprint(); 22 flag=false; 23 notify(); 24 } 25 } 26 public void print2() 27 { 28 synchronized(this) 29 { 30 if(flag==true) 31 { 32 try { 33 this.wait(); 34 } catch (InterruptedException e) { 35 e.printStackTrace(); 36 } 37 } 38 realprint(); 39 flag=true; 40 notify(); 41 } 42 } 43 public void realprint() 44 { 45 if(i<printStr.length()) 46 { 47 System.out.println(Thread.currentThread().getName() +" print "+printStr.charAt(i)); 48 i++; 49 } 50 } 51 } 52 class MyThread1 extends Thread 53 { 54 public Info info=null; 55 public MyThread1(Info in) { 56 this.info=in; 57 } 58 @Override 59 public void run() 60 { 61 while(info.i<info.printStr.length()) 62 info.print2(); 63 } 64 } 65 class MyThread2 extends Thread 66 { 67 public Info info=null; 68 public MyThread2(Info in) { 69 this.info=in; 70 } 71 @Override 72 public void run() 73 { 74 while(info.i<info.printStr.length()) 75 info.print1(); 76 } 77 } 78 public class main { 79 public static void main(String[] args) { 80 //两个线程 交替打印字符串 81 Info info=new Info(); //互斥资源 82 MyThread1 mthread1=new MyThread1(info); 83 MyThread2 mthread2=new MyThread2(info); 84 new Thread(mthread1).start(); 85 new Thread(mthread2).start(); 86 } 87 88 }
代码2
1 package MyThreadMethod; 2 3 import java.util.concurrent.locks.Condition; 4 import java.util.concurrent.locks.ReentrantLock; 5 6 class Info 7 { 8 String printStr="i think this is ok"; 9 int i=0; 10 public void print1() 11 { 12 if(i<printStr.length()) 13 { 14 System.out.println(Thread.currentThread().getName() +" print "+printStr.charAt(i)); 15 i++; 16 } 17 } 18 } 19 public class threadMethod { 20 ReentrantLock lock=new ReentrantLock(); 21 Condition con1=lock.newCondition(); 22 Condition con2=lock.newCondition(); 23 boolean flag=false; 24 public class MyThread1 extends Thread 25 { 26 public Info info=null; 27 MyThread1(Info info) 28 { 29 this.info=info; 30 } 31 @Override 32 public void run() { 33 while(info.i<info.printStr.length()) 34 { 35 lock.lock(); 36 try 37 { 38 while(flag==true) 39 { 40 try { 41 con1.await(); 42 } catch (InterruptedException e) { 43 // TODO Auto-generated catch block 44 e.printStackTrace(); 45 } 46 } 47 info.print1(); 48 flag=true; 49 con2.signal(); 50 } 51 finally 52 { 53 lock.unlock(); 54 } 55 } 56 } 57 } 58 59 public class MyThread2 extends Thread 60 { 61 public Info info=null; 62 MyThread2(Info info) 63 { 64 this.info=info; 65 } 66 @Override 67 public void run() { 68 while(info.i<info.printStr.length()) 69 { 70 lock.lock(); 71 try 72 { 73 while(flag==false) 74 { 75 try { 76 con2.await(); 77 } catch (InterruptedException e) { 78 // TODO Auto-generated catch block 79 e.printStackTrace(); 80 } 81 } 82 info.print1(); 83 flag=false; 84 con1.signal(); 85 } 86 finally 87 { 88 lock.unlock(); 89 } 90 } 91 } 92 } 93 public static void main(String[] args) { 94 threadMethod tm=new threadMethod(); 95 Info info=new Info(); 96 MyThread1 thread1=tm.new MyThread1(info); 97 MyThread2 thread2=tm.new MyThread2(info); 98 thread1.start(); 99 thread2.start(); 100 101 102 } 103 104 }
3 不同写法
1 class Info 2 { 3 String printStr="i think this is ok"; 4 int i=0; 5 public void print() 6 { 7 if(i<printStr.length()) 8 { 9 System.out.println(Thread.currentThread().getName() +" print "+printStr.charAt(i)); 10 i++; 11 } 12 } 13 } 14 public class main { 15 private static Object LOCK = new Object(); 16 static Info info=new Info(); //互斥资源 17 static boolean flag=false; //false for a ,true for b 18 public static void main(String[] args) { 19 //两个线程 交替打印字符串 20 Thread a=new Thread(){ 21 public void run() { 22 while(info.i<info.printStr.length()) 23 synchronized (LOCK) { 24 { 25 if(false==flag) 26 { 27 flag=true; 28 info.print(); 29 LOCK.notify();//在这里虽然唤醒了另一个线程b，但锁并没有释放 30 try { 31 if(info.i<info.printStr.length()) 32 LOCK.wait();//在wait后的瞬间线程b得到锁 33 } catch (InterruptedException e) { 34 e.printStackTrace(); 35 } 36 } 37 } 38 } 39 }; 40 }; 41 Thread b=new Thread(){ 42 public void run() { 43 while(info.i<info.printStr.length()) 44 synchronized (LOCK) { 45 { 46 if(true==flag) 47 { 48 flag=false; 49 info.print(); 50 LOCK.notify();//在这里虽然唤醒了另一个线程b，但锁并没有释放 51 try { 52 if(info.i<info.printStr.length()) 53 LOCK.wait();//在wait后的瞬间线程b得到锁 54 } catch (InterruptedException e) { 55 e.printStackTrace(); 56 } 57 } 58 } 59 } 60 }; 61 }; 62 a.start(); 63 b.start(); 64 } 65 66 }