Teaching Scanner Class/Formatting

[James Chegwidden]

I was wondering about the Scanner class for I/O and files as well as formatting numbers.

Since it is the with the newest version of Java is Scanner now the "prefered" way of teaching I/O. I see now three ways of showing keyboard input:

1. Using Scanner class
2. Using BufferedReader
3. Using JOptionPane dialog box

Should I spend time showing them all three ways or concentrate my efforts with just Scanner. With previous versions I would show both ways.

Same question with Text Files
1. Use Scanner/FileInputStream
2. Use BufferReader/FileReader

Finally, what about formatting:
1. Use DecimalFormat
2. Use printf


Would appreciate opinions from both teacher and other professionals on the preferred way to teach these topics