java入门：文件操作

import java.io.FileInputStream; 
import java.io.FileOutputStream;
import java.io.PrintStream;

public class Main {
	
	public static void f_useFileIN(String name) {        	 
        try {
        	System.setIn(new FileInputStream(name));
        } 
        catch (Exception e) {
        	System.err.println("Error instream!");
        }              	
	}
	
	public static void f_useFileOUT(String name) {
        try {
        	System.setOut(new PrintStream(new FileOutputStream(name)));
        } 
        catch (Exception e) {
        	System.err.println("Error outstream!");
        }
	}
	
	public static void main(String args[]) {		
		//f_useFileIN("data.in");
		//f_useFileOUT("data.out");
		
		
        System.err.println("OK");
	}
}