Java文件输入输出

public static void FileIO(String filename){
    FileInputStream fis = null;
    try {
        fis = new FileInputStream(filename+".in");
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    
    System.setIn(fis);
    
    PrintStream ps = null;
    try {
        ps = new PrintStream(new FileOutputStream(filename+".out"));
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    System.setOut(ps);
}

其中try语句可以让eclipse自动补全。

配套赠送cin/cout版Java，令人怀念的C++。

import java.io.*;
import java.util.*;
import java.math.*;

public class Main {
    public static void solve(Scanner cin,PrintStream cout){
        while(cin.hasNext()){
            int n=cin.nextInt();
            cout.print(n);
        }
    }
    
    public static void main(String[] args) {
        //setFileIO("D://test");
        Scanner cin=new Scanner(System.in);
        PrintStream cout=new PrintStream(System.out);
        
        solve(cin,cout);
        
        cin.close();
        cout.close();
    }
    
    public static void FileIO(String filename){
        FileInputStream fis = null;
        try {
            fis = new FileInputStream(filename+".in");
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        System.setIn(fis);
        
        PrintStream ps = null;
        try {
            ps = new PrintStream(new FileOutputStream(filename+".out"));
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        System.setOut(ps);
    }
}