暂停线程（suspend和resume）

不多说代码演示：

public class MyThread extends Thread {

	private long i = 0;

	public long getI() {
		return i;
	}

	public void setI(long i) {
		this.i = i;
	}

	@Override
	public void run() {
		while (true) {
			i++;
		}
	}

}

public class Run {

	public static void main(String[] args) {

		try {
			MyThread thread = new MyThread();
			thread.start();
			Thread.sleep(3000);
			// A
			thread.suspend();
			System.out.println("A= " + System.currentTimeMillis() + " i="
					+ thread.getI());
			Thread.sleep(3000);
			System.out.println("A= " + System.currentTimeMillis() + " i="
					+ thread.getI());
			// B
			thread.resume();
			Thread.sleep(3000);

			// C
			thread.suspend();
			System.out.println("B= " + System.currentTimeMillis() + " i="
					+ thread.getI());
			Thread.sleep(3000);
			System.out.println("B= " + System.currentTimeMillis() + " i="
					+ thread.getI());
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

}

suspend和resume方法缺点--独占

public class SynchronizedObject {

	synchronized public void printString() {
		System.out.println("begin");
		if (Thread.currentThread().getName().equals("a")) {
			System.out.println("a线程永远 suspend了！");
			Thread.currentThread().suspend();
		}
		System.out.println("end");
	}

}
public class Run {

	public static void main(String[] args) {
		try {
			final SynchronizedObject object = new SynchronizedObject();

			Thread thread1 = new Thread() {
				@Override
				public void run() {
					object.printString();
				}
			};
			thread1.setName("a");
			thread1.start();

			Thread.sleep(1000);
			Thread thread2 = new Thread() {
				@Override
				public void run() {
					System.out
							.println("thread2启动了，但进入不了printString()方法！只打印1个begin");
					System.out
							.println("因为printString()方法被a线程锁定并且永远的suspend暂停了！");
					object.printString();
				}
			};
			thread2.start();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}

public class MyThread extends Thread {
	private long i = 0;

	@Override
	public void run() {
		while (true) {
			i++;
			System.out.println(i);
		}
	}
}
public static void main(String[] args) {

		try {
			MyThread thread = new MyThread();
			thread.start();
			Thread.sleep(1000);
			thread.suspend();
			System.out.println("main end!");
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

suspend和resume方法缺点--不同步数据

public class MyObject {

	private String username = "1";
	private String password = "11";

	public void setValue(String u, String p) {
		this.username = u;
		if (Thread.currentThread().getName().equals("a")) {
			System.out.println("停止a线程！");
			Thread.currentThread().suspend();
		}
		this.password = p;
	}

	public void printUsernamePassword() {
		System.out.println(username + " " + password);
	}
}

public static void main(String[] args) throws InterruptedException {

		final MyObject myobject = new MyObject();

		Thread thread1 = new Thread() {
			public void run() {
				myobject.setValue("a", "aa");
			};
		};
		thread1.setName("a");
		thread1.start();

		Thread.sleep(500);

		Thread thread2 = new Thread() {
			public void run() {
				myobject.printUsernamePassword();
			};
		};
		thread2.start();

	}