Java快速输入输出

 有时候（eg:做算法题时）为了提高速度可以用输入输出流，比Scanner要快！

示例代码：

import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.io.PrintStream; import java.io.Writer; public class 快速输入输出 { public static void main(String[] args) throws IOException { // TODO 自动生成的方法存根 BufferedReader bur1=new BufferedReader(new InputStreamReader(System.in)); //想输入一个数（数组长度） String c=bur1.readLine(); int b=Integer.valueOf(c); //想输入一个数组 String aString=bur1.readLine(); String a[]=aString.split(" "); int v[]=new int[b]; for (int i = 0; i < a.length; i++) { v[i]=Integer.valueOf(a[i]); } //为了获得最高效率，可考虑将 OutputStreamWriter 包装到 BufferedWriter 中，以避免频繁调用转换器。 //Writer writer=new OutputStreamWriter(System.out); BufferedWriter writer=new BufferedWriter(new OutputStreamWriter(System.out)); for (int i = 0; i < a.length; i++) { writer.write(a[i]); } writer.write("\r");// writer.write("hello"); writer.flush();//释放资源 } }

上面代码中的split()是以空格" "为分隔的，这样以一个数组接收没有问题，但是当以空字符串""为分隔时，再直接接收就有问题了，split()会默认字符串的开头最前面也有一个空串，这第一个空串就会被数组的第一个元素接收。

我在做2019蓝桥杯java迷宫哪道题时用快速输入输出流时遇到了上面的问题，解决如下：

样例输入：

01010101001011001001010110010110100100001000101010 00001000100000101010010000100000001001100110100101 01111011010010001000001101001011100011000000010000 01000000001010100011010000101000001010101011001011 00011111000000101000010010100010100000101100000000 11001000110101000010101100011010011010101011110111 00011011010101001001001010000001000101001110000000 10100000101000100110101010111110011000010000111010 00111000001010100001100010000001000101001100001001 11000110100001110010001001010101010101010001101000 00010000100100000101001010101110100010101010000101 11100100101001001000010000010101010100100100010100 00000010000000101011001111010001100000101010100011 10101010011100001000011000010110011110110100001000 10101010100001101010100101000010100000111011101001 10000000101100010000101100101101001011100000000100 10101001000000010100100001000100000100011110101001 00101001010101101001010100011010101101110000110101 11001010000100001100000010100101000001000111000010 00001000110000110101101000000100101001001000011101 10100101000101000000001110110010110101101010100001 00101000010000110101010000100010001001000100010101 10100001000110010001000010101001010101011111010010 00000100101000000110010100101001000001000000000010 11010000001001110111001001000011101001011011101000 00000110100010001000100000001000011101000000110011 10101000101000100010001111100010101001010000001000 10000010100101001010110000000100101010001011101000 00111100001000010000000110111000000001000000001011 10000001100111010111010001000110111010101101111000

输入代码：

下面我的解决方法是先完全接收，再利用数组的Arrays.copyOfRange(tmp, 1,tmp.length)函数将下标1开始的值拷贝到另一个数组中去；或者分配数组时列长度多分配一个，这样列标为0的 元素不用就行。

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.Arrays; import java.util.Scanner; public class Main { public static void main(String[] args) throws IOException { // TODO 自动生成的方法存根 Scanner in=new Scanner(System.in); BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); int[][] a=new int[30][50]; for(int i=0;i<30;i++){ String str=br.readLine(); String tmp[]=str.split(""); //当以空串为分隔符时，字串的开头也会被视为空串！！！故需要将第一个去掉 String[] s=Arrays.copyOfRange(tmp, 1,tmp.length); System.out.println(Arrays.toString(s)); //System.out.println(s.length); for(int j=0;j<50;j++){ System.out.print(s[j]); //a[i][j]=Integer.parseInt(s[j]); //System.out.print(a[i][j]); } System.out.println(); } } }