初學多線程求教，調用synchronized(Class.forName(""))時拋出異常

[东门吹雪]

public class J_BlockClass extends Thread 
{
	public static int m_data=0;
	public static int m_times=1000;
	public int m_ID;
	public boolean m_done;
	
	J_BlockClass(int id)
	{
		m_ID = id;
	}
	
	public void run()
	{
		m_done = false;
		int d = ((m_ID%2==0) ? 1:-1);
		System.out.println("Run Thread: " +m_ID+ "(Increment is: " + d + ")");
		
		try
		{
			synchronized(Class.forName("J_BlockClass"))
			{
				System.out.println("Thread: " + m_ID + "Enter into synchronized block, m_data= " + m_data);
				for (int i=0; i<m_times; i++)
					for(int j=0; j<m_times; j++)
						m_data += d;
				System.out.println("Thread: " +m_ID + "Leave synchronized block, m_data= " + m_data);
			}
		}
		catch(ClassNotFoundException e)
		{
			e.printStackTrace();
			System.err.println(e);
		}
		
		m_done = true;
		System.out.println("End Thread: " + m_ID);
	}
	
	public static void main(String args[])
	{
		J_BlockClass t1 = new J_BlockClass(1);
		J_BlockClass t2 = new J_BlockClass(2);
		t1.m_done = false;
		t2.m_done = false;
		t1.start();
		t2.start();
		
		while (!t1.m_done || !t2.m_done)
			;
		System.out.println("The result is: m_data = " + m_data);
	}
}

拋出異常：
java.lang.ClassNotFoundException: J_BlockClass
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301

。。。。。。。。。。。。

[shuwei003]

这个我这里运行没报错，输出：
Run Thread: 1(Increment is: -1)
Thread: 1Enter into synchronized block, m_data= 0
Run Thread: 2(Increment is: 1)
Thread: 1Leave synchronized block, m_data= -1000000
End Thread: 1
Thread: 2Enter into synchronized block, m_data= -1000000
Thread: 2Leave synchronized block, m_data= 0
End Thread: 2
The result is: m_data = 0

是不是你用了包了，如果用了包应该写Class.forName("包名.J_BlockClass")

[东门吹雪]

[Quote=引用 1 楼 shuwei003 的回复:]
是不是你用了包了，如果用了包应该写Class.forName("包名.J_BlockClass")
[/Quote]

哈哈，果然啊， you are so smart ，ths，看來我還得加油啊