JAVA 对象被垃圾回收后其成员变量可用吗？

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package test;

public class mytest {
	public static void main(String[] args) throws Exception {
		HandleBuffer hb = null;
		{
			Buffer buf = new Buffer();
			hb = new HandleBuffer(buf.getBuf());
			buf = null;
		}
		System.out.println("Has Buffer gone away?");
		System.in.read();
		Runtime.getRuntime().gc();
		System.out.println("first gc finished!");
		System.in.read();
		System.out.println("Has Buffer gone away?");
		Thread.currentThread().sleep(1000);
		System.out.println(hb);
		System.in.read();	
	}
}

class Buffer{
	private byte[] buf = new byte[1024];
	public Buffer(){
		this.buf = "abc".getBytes();
	}
	public byte[] getBuf(){
		return this.buf;
	}
	@Override
	protected void finalize() throws Throwable {
		System.out.println("Buffer gone away!");
	}
}

class HandleBuffer{
	byte[] buf = null;
	public HandleBuffer(byte[] buf){
		this.buf = buf;
	}
	
	@Override
	public String toString() {
			return new String(buf);
	}
}

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Has Buffer gone away?

first gc finished!
Has Buffer gone away?
Buffer gone away!  //此时对象已被垃圾回收
abc                //访问数据正常