go to previous page   go to home page   go to next page

Answer:

Mostly from the keyboard.


Input Redirection

A program that reads input from the keyboard can also read input from a text file. This is called input redirection, and is a feature of the command line interface of most operating systems.

Say that you have a program named echo.java that reads characters from the keyboard and echoes them to the monitor. Here is how the program usually works:

C:\temp> java echo
Enter your input: 
User types this.
You typed: User types this.
C:\temp>

Without making any changes to the program, its input can come from a disk file. Say that there is a file input.txt in the same subdirectory as the program, and that it contains the text

This is text from the file.

You can do this:

C:\temp> java echo < input.txt
Enter your input:
You typed: This is text from the file.
C:\temp> 

"< input.txt" connects the file input.txt to the program which then reads it instead of the keyboard. As with input redirection, this is a feature of the command line interface, not a feature specific to Java.

The program's output is sent to the monitor, including the (now useless) prompt.

The file input.txt must exist before the program is run. Create it with a text editor.


QUESTION 2:

Is there a limit to the size of the input file?


go to previous page   go to home page   go to next page