现有:D-f是一个对java.io.File实例的合法引用-fw是一个对java.io.FileWriter实例的合法引用-bw是一个对java.io.BufferedWriter实例的合法引用以下哪一项无效?()
A、PrintWriterprtWtr=newPrintWriter(f);
B、PrintWriterprtWtr=newPrintWriter(fw);
C、PrintWriterprtWtr=newPrintWriter(bw);
D、BufferWriterbufWtr=newBufferedWriter(f);
E、BufferWriterbufWtr=newBufferedWriter(fw);
F、BufferWriterbufWtr=newBufferedWriter(bw);