java多线程交替打印两个数

「爱情、让人受尽委屈。」 2021-09-24 10:42 272阅读 0赞

方法1，使用wait和notify

package com.thread;
    
    public class T01 {
    
    	public static void main(String[] args) {
    		char[] char1 = "AAAAAA".toCharArray();
    		char[] char2 = "BBBBBB".toCharArray();
    		Object object = new Object();
    		
    		Thread thread1 = new Thread(()  -> {
    				synchronized(object){//使用notify和wait时，必须要选获取到锁
    					for (int i = 0; i < char1.length; i++) {
    						try {
    							System.out.print(char1[i]);
    							object.notify();
    							object.wait();
    						} catch (InterruptedException e) {
    							e.printStackTrace();
    						}
    					}
    					object.notify();//必须加上，否则程序无法结束，两个线程总有一个最后是wait状态，所以此处必须加
    			}
    				
    		},"t1");
    		
    		
    		Thread thread2 = new Thread( () -> {
    				synchronized(object){
    					for (int i = 0; i < char2.length; i++) {
    						try {
    							System.out.print(char2[i]);
    							object.notify();
    							object.wait();
    						} catch (InterruptedException e) {
    							e.printStackTrace();
    						}
    					}
    					object.notify();
    			}
    		},"t2");
    		
    		thread1.start();
    		thread2.start();
    		
    	}
    }

方法2，使用LockSupport方法

package com.thread;
    
    import java.util.concurrent.locks.LockSupport;
    
    public class T02 {
    	static Thread thread1 ;
    	static Thread thread2 ;
    	public static void main(String[] args) {
    		char[] char1 = "AAAAAA".toCharArray();
    		char[] char2 = "BBBBBB".toCharArray();
    		
    		thread1 = new Thread(() -> {
    				for (int i = 0; i < char1.length; i++) {
    					System.out.print(char1[i]);
    					LockSupport.unpark(thread2);
    					LockSupport.park();
    				}
    		},"t1");
    		
    		 thread2 = new Thread(() -> {
    				for (int i = 0; i < char2.length; i++) {
    					LockSupport.park();
    					System.out.print(char2[i]);
    					LockSupport.unpark(thread1);
    				}
    		},"t2");
    		
    		thread1.start();
    		thread2.start();
    		
    	}
    	
    	
    }

方法3，使用CAS自旋锁

package com.thread;
    
    public class T03 {
    	enum ReadEnum{
    		T1,
    		T2;
    	}
    	static volatile ReadEnum r  = ReadEnum.T1;
    	public static void main(String[] args) {
    		char[] char1 = "AAAAAA".toCharArray();
    		char[] char2 = "BBBBBB".toCharArray();
    		Thread thread1 = new Thread(() ->{
    			for (int i = 0; i < char1.length; i++) {
    				while (r != ReadEnum.T1) {
    				}
    				System.out.print(char1[i]);
    				r = ReadEnum.T2;
    			}
    		},"t1");
    		
    		
    		Thread thread2 = new Thread(() ->{
    			for (int i = 0; i < char2.length; i++) {
    				while (r != ReadEnum.T2) {
    				}
    				System.out.print(char2[i]);
    				r = ReadEnum.T1;
    			}
    		},"t2");
    		
    		thread1.start();
    		thread2.start();
    		
    		
    	}
    }

方法4，使用Condition方法

package com.thread;
    
    import java.util.concurrent.locks.Condition;
    import java.util.concurrent.locks.ReentrantLock;
    
    
    public class T04 {
    
    	public static void main(String[] args) {
    		char[] char1 = "AAAAAA".toCharArray();
    		char[] char2 = "BBBBBB".toCharArray();
    		
    		ReentrantLock lock = new ReentrantLock();
    		Condition condition1 = lock.newCondition();
    		Condition condition2 = lock.newCondition();
    		
    		Thread thread1 = new Thread(() ->{
    			try {
    				lock.lock();
    				for (int i = 0; i < char1.length; i++) {
    					System.out.print(char1[i]);
    					condition2.signal();//唤醒线程2执行
    					condition1.await();//线程1等待
    				}
    				condition2.signal();
    			}catch (Exception e) {
    				e.printStackTrace();
    			}finally{
    				lock.unlock();
    			}
    		},"t1");
    		
    		Thread thread2 = new Thread(() ->{
    			try {
    				lock.lock();
    				for (int i = 0; i < char2.length; i++) {
    					System.out.print(char2[i]);
    					condition1.signal();
    					condition2.await();
    				}
    				condition1.signal();
    			} catch (Exception e) {
    				e.printStackTrace();
    			}finally{
    				lock.unlock();
    			}
    
    		},"t2");
    		
    		thread1.start();
    		thread2.start();
    		
    		
    	}
    }

打印结果：  
  
  
Condition与notify相比的好处是，Condition可以指定需要唤醒的线程，而notify是无法指定的，只能随机唤醒一个或者全唤醒(notifyAll)