Java-快读快写

一、快读-BufferedReader实现 

为了方便，自己写了个类

注意：BufferedReader需要抛异常（throws IOException）

class in 
{
    static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer tokenizer = new StringTokenizer("");
    
    // nextLine()读取字符串
    static String nextLine() throws IOException   { return reader.readLine(); }
    
    // next()读取字符串
    static String next() throws IOException 
    {
        while (!tokenizer.hasMoreTokens())  tokenizer = new StringTokenizer(reader.readLine());
        return tokenizer.nextToken();
    }

    // 读取一个int型数值
    static int nextInt() throws IOException  { return Integer.parseInt(next()); }

    // 读取一个double型数值
    static double nextDouble() throws IOException { return Double.parseDouble(next()); }
    
    // 读取一个long型数值
    static long nextLong() throws IOException  { return Long.parseLong(next());}
    
    // 读取一个BigInteger
    static BigInteger nextBigInteger() throws IOException 
    { 
        BigInteger d = new BigInteger(in.nextLine());
        return d;
    }
}

二、快写-PrintWriter实现

注意：

1、PrintWriter也需要抛异常（throws IOException）

2、需要手动刷洗缓存区，要不然不输出（pw.flush();）

三、实操代码

package hly;
import java.io.*;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.HashMap;
import java.util.StringTokenizer;

class in 
{
    static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer tokenizer = new StringTokenizer("");
    
    // nextLine()读取字符串
    static String nextLine() throws IOException   { return reader.readLine(); }
    
    // next()读取字符串
    static String next() throws IOException 
    {
        while (!tokenizer.hasMoreTokens())  tokenizer = new StringTokenizer(reader.readLine());
        return tokenizer.nextToken();
    }

    // 读取一个int型数值
    static int nextInt() throws IOException  { return Integer.parseInt(next()); }

    // 读取一个double型数值
    static double nextDouble() throws IOException { return Double.parseDouble(next()); }
    
    // 读取一个long型数值
    static long nextLong() throws IOException  { return Long.parseLong(next());}
    
    // 读取一个BigInteger
    static BigInteger nextBigInteger() throws IOException 
    { 
        BigInteger d = new BigInteger(in.nextLine());
        return d;
    }
}

public class Main 
{
    public static void main(String[] args) throws IOException 
    {
        PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
        
        // 读入int
        int a = in.nextInt();
        pw.println(a);
        
        // 读入long
        long b = in.nextLong();
        pw.println(b);
        
        // 读入double
        double c = in.nextDouble();
        pw.println(c);
        
        // 读入字符串
        // nextLine方式输入的字符串可以含有空格(空格字符也会存储在字符串里面),也就是说它是以回车作为输入的结束符。
        String s1 = in.nextLine();
        pw.println(s1);
        
        // 读入字符串
        // next输入的字符串不能含有空格，它以空格、tab、回车作为输入的结束符。
        String s2 = in.next();
        pw.println(s2);
        
        // 读入BigInteger
        BigInteger d = in.nextBigInteger();
        pw.append("" + d);
        
        pw.flush();
    }
}