java避免死锁的常见方法代码解析

package thread;
public class DeadLockDemo {
	private static String A = "A";
	private static String B = "B";
	public static void main(String args[]) {
		new DeadLockDemo().deadLock();
	}
	private void deadLock() {
		// 线程thread_1 
		Thread thread_1 = new Thread(new Runnable() {
			@Override 
			   public void run() {
				synchronized (A) {
					System.err.println("--thread_1 lock A----");
					synchronized (B) {
						System.err.println("--thread_1 lock B----");
					}
				}
			}
		}
		);
		// 线程thread_2 
		Thread thread_2 = new Thread(new Runnable() {
			@Override 
			   public void run() {
				synchronized (B) {
					System.out.println("--thread_2 lock B----");
					synchronized (A) {
						System.out.println("--thread_2 lock A----");
					}
				}
			}
		}
		);
		thread_1.start();
		thread_2.start();
	}
}

"Thread-1" prio=6 tid=0x000000000cb13800 nid=0x19ac waiting for monitor entry [0 
x000000000d67f000] 
 java.lang.Thread.State: BLOCKED (on object monitor) 
  at thread.DeadLockDemo$2.run(DeadLockDemo.java:35) 
  - waiting to lock <0x00000007d5a9be88> (a java.lang.String) 
  - locked <0x00000007d5a9beb8> (a java.lang.String) 
  at java.lang.Thread.run(Unknown Source) 
 
"Thread-0" prio=6 tid=0x000000000cb0e800 nid=0x6bc waiting for monitor entry [0x 
000000000d48f000] 
 java.lang.Thread.State: BLOCKED (on object monitor) 
  at thread.DeadLockDemo$1.run(DeadLockDemo.java:21) 
  - waiting to lock <0x00000007d5a9beb8> (a java.lang.String) 
  - locked <0x00000007d5a9be88> (a java.lang.String) 
  at java.lang.Thread.run(Unknown Source)