Java中BufferedReader与Scanner读入的区别详解

BufferedReader br = new BufferedReader (newInputStreamReader(System.in));

package com.zxt.base;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.Scanner;

public classSystemInTest {

     private static Scanner sc;

     public static void main(String[] args) {

         // 使用Scanner输入

         sc = new Scanner(System.in);

         int num1 = sc.nextInt();

         int num2 = sc.nextInt();

         System.out.println( "num1 + num2 = " + (num1+ num2));

         // 使用BufferReader输入

         InputStreamReaderisr = newInputStreamReader(System.in);

         BufferedReaderbr = new BufferedReader(isr);

         try {

             int num3 = Integer.parseInt(br.readLine());

             int num4 = Integer.parseInt(br.readLine());

             System.out.println( "num3 + num4 = " + (num3+ num4));

         } catch (NumberFormatException | IOException e) {

             e.printStackTrace();

         }      

         // 使用Scanner输入会遇到的问题

         System.out.println();

         System.out.print( "Enter an Integer:" );

         int intValue = sc.nextInt();

         System.out.print( "Enter a String:" );

         StringstrValue = sc.nextLine();

         System.out.printf( "You have entered intValue is " + intValue+ " and strValue is " + strValue);

         // 问题原因：由于nextXXX()方法忽略换行符，但是nextLine()并不忽略它。所以如果我们在nextXXX()方法后面使用nextLine()将会出现问题

         // 解决方案是：在使用nextXXX()方法后，在使用nextLine()读取下一行数据前，多使用一个nextLine()用来消耗换行符

         // int intValue = sc.nextInt();

         // sc.nextLine();

         // String strValue = sc.nextLine();

         // 或者使用BufferReader不会出现该问题

         System.out.println();

         try {

             System.out.print( "Enter an Integer:" );

             int intValue1 = Integer.parseInt(br.readLine());

             System.out.print( "Enter a String:" );

             StringstrValue1 = br.readLine();

             System.out.printf( "You have entered intValue1 is " + intValue1+ " and strValue1 is " + strValue1);

         } catch (NumberFormatException | IOException e) {

             e.printStackTrace();

         }

     }

}