final 可以使变量“不可改变”、使方法“不能被重写”
private final String name = "foo"; //the reference name can never change
public final String toString() { return "NULL"; }
finally 被用在 try/catch 声明中,用来表示代码一定要被执行
lock.lock();
try {
//do stuff
} catch (SomeException se) {
//handle se
} finally {
lock.unlock(); //always executed, even if Exception or Error or system.exit()
}