哲学家问题，java去除死锁的解法，琢磨了半天，要避免死锁就必须在得不到右边的筷子情况下放弃左边的筷子，如此才可！正所谓，退一步海阔天空。。。。

public class Zhexuejia {

	public static void main(String[] args) throws Exception{
		  new Zhexuejia().t();
	}
	public void t() throws Exception{
		Jia j1 = new Jia("哲学家1", x1, x2);
		Jia j2 = new Jia("哲学家2", x2, x3);
		Jia j3 = new Jia("哲学家3", x3, x4);
		Jia j4 = new Jia("哲学家4", x4, x5);
		Jia j5 = new Jia("哲学家5", x5, x1);
		j1.start();
		j2.start();
		j3.start();
		j4.start();
		j5.start();
		j1.join();
		j2.join();
		j3.join();
		j4.join();
		j5.join();
	}
	class Kuaizi{
		String name;
		public Kuaizi(String name){
			this.name = name;
		}
		boolean enable = true;
		public boolean pickup(Kuaizi r){
			synchronized (this) {
				int c = 0;
				while(!enable&&c<3){
					try {
						c++;
						this.wait(50);//先放出去自己让别人用
					} catch (InterruptedException e) { 
						e.printStackTrace();
					}
				}
				if(!enable){//尝试3次努力还是没有得到就放弃前面的r
					if(r != null)
						r.down();
					return false;
				}
				enable = false;
				return true;
			}
		}
		public void down(){
			synchronized (this) {
				enable = true;
				notifyAll();
			} 
		}
		public String toString(){
			return name;
		}
	} 
	private Kuaizi x1 =  new Kuaizi("x1"); 
	private Kuaizi x2 =  new Kuaizi("x2"); 
	private Kuaizi x3 =  new Kuaizi("x3"); 
	private Kuaizi x4 =  new Kuaizi("x4"); 
	private Kuaizi x5 =  new Kuaizi("x5"); 

	class Jia extends Thread{ 
		Kuaizi lX, rX;
		String name;
		public Jia(String name, Kuaizi lX, Kuaizi rX){
			this.name = name;
			this.lX = lX;
			this.rX = rX;
		}
		public void run(){ 
			int c = 100;			
			boolean rs;
			while(c-- > 0){
				try { 
					System.out.println(name + " 想吃饭");
					rs = lX.pickup(null);
//					synchronized (lX) {//先得到坐标的筷子
					if(rs){
						System.out.println(name + " 获得了 " + lX + "筷子，等待右边的...");
					}else{
						System.out.println(name + " 得不到"+lX+"，悲催啊");
						continue;
					}
					rs = rX.pickup(lX);
//						synchronized (rX) {//再得到右边的筷子，如果得不到也不放弃左边的，容易死锁，想避免就必须在得不到的情况下放弃左边的筷子		
							if(rs){
								System.out.println(name + " 终于获得了 " + rX
										+ "筷子，开始吃饭...");
							}else{
								System.out.println(name + " 得不到"+rX+"，放弃"+lX+",悲哀啊");
								continue;
							} 
//						}

						System.out.println(name + " 放弃 " + rX + "筷子");
						rX.down();
//					}
					System.out.println(name + " 放弃 " + lX + "筷子");
					lX.down();
				} catch (Exception e) { 
					e.printStackTrace();
				}
			}
		}
	}
}