java键盘输入语句_java的输入语句小结

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1.使用Scanner

使用时需要引入包import java.util.Scanner;首先定义Scanner对象

Scanner sc = new Scanner(System.in);

如果要输入整数，则 int n = sc.nextInt();

String类型的，则String temp = sc.next();

比如：

import java.util.Scanner;public class Test { public static void main(String[] args) {

Scanner scanner = new Scanner(System.in); int[] days = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; int month = -1; while(true) { try {

System.out.print(“请输入月份：”);

month = scanner.nextInt(); if(month >= 1 && month <= 12) { break;

}

System.out.println(“** 请输入正确的月份 **”);

} catch (Exception e) {

System.out.println(“** 格式错误！请输入数字 **”);

scanner.next();

}

}

System.out.println(month + ” 月份有：” + days[month – 1] + ” 天”);

}

}

2.使用BufferedReader

用前需要引入 import java.io.Reader;

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

String input = br.readLine();

比如：

==================================================================================================

import java.io.*;

public class importtext {

public static void main(String[] args) {

String st;

int num;

float fnum;

try{

System.out.print(“输入：”);

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

st = br.readLine();

System.out.print(“输入一个数：”);

num = Integer.parseInt(br.readLine());

System.out.print(“输入一个浮点数：”);

fnum = Float.parseFloat(br.readLine());

System.out.print(“输出：”+st+’\n’);

System.out.print(“输出：”+num+’\n’);

System.out.print(“输出：”+fnum+’\n’);

}catch(IOException e){}

}

}

==================================================================================================

package com.s2;

import java.io.*;

public class Input

{

public static void main(String[] args)throws IOException

{

while(true)

{

BufferedReader buf;

String str;

buf =new BufferedReader(new InputStreamReader(System.in));

System.out.println(“Input a string:”);

str=buf.readLine();

System.out.println(“String=”+str);

}

}

}

==================================================================================================

应该注意的是:Java把从键盘输入的数据一律看作是字符串，因此若要从键盘输入并让系统认可是数值型数据，必须经过转换。

比如：

package com.s2;

import java.io.*;

public class Input

{

public static void main(String[] args)throws IOException

{

while(true)

{

int num;

BufferedReader buf;

String str;

buf =new BufferedReader(new InputStreamReader(System.in));

System.out.println(“Input an integer:”);

str=buf.readLine();

num=Integer.parseInt(str);

System.out.println(“String=”+str);

System.out.println(“Integer=”+str);

}

}

}

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