等待/通知之交叉备份

public class DBTools {

	volatile private boolean prevIsA = false;

	synchronized public void backupA() {
		try {
			while (prevIsA == true) {
				wait();
			}
			for (int i = 0; i < 5; i++) {
				System.out.println("A线程备份★★★★★");
			}
			prevIsA = true;
			notifyAll();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

	synchronized public void backupB() {
		try {
			while (prevIsA == false) {
				wait();
			}
			for (int i = 0; i < 5; i++) {
				System.out.println("B线程备份☆☆☆☆☆");
			}
			prevIsA = false;
			notifyAll();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}
}

public class BackupA extends Thread {

	private DBTools dbtools;

	public BackupA(DBTools dbtools) {
		super();
		this.dbtools = dbtools;
	}

	@Override
	public void run() {
		dbtools.backupA();
	}

}

public class BackupB extends Thread {

	private DBTools dbtools;

	public BackupB(DBTools dbtools) {
		super();
		this.dbtools = dbtools;
	}

	@Override
	public void run() {
		dbtools.backupB();
	}

}

public class Run {

	public static void main(String[] args) throws InterruptedException {
		DBTools dbtools = new DBTools();
		for (int i = 0; i < 20; i++) {
			BackupB output = new BackupB(dbtools);
			output.start();
			Thread.sleep(500);
			BackupA input = new BackupA(dbtools);
			input.start();
		}
	}

}