JAVA中如何实现从键盘中输入一个整数? [JAVA]从键盘输入一个任意整数，求各位数字之和。
JAVA\u5982\u4f55\u8f93\u5165\u4e00\u4e2a\u6574\u6570\u53ef\u4ee5\u901a\u8fc7\u201dScanner\u201c\u51fd\u6570
\u76f4\u63a5\u8f93\u5165\u53c2\u6570\u7684\u5f62\u5f0f\uff0c\u6765\u5b9e\u73b0\u8f93\u5165\u8bed\u53e5\uff0c\u4e3e\u4f8b\uff1a
import
java.util.Scanner;
public
class
Test
{
public
static
void
main(String[]
args)
{
Scanner
input=new
Scanner(System.in);
System.out.println("\u8bf7\u8f93\u5165\u4e00\u4e2a\u6574\u6570\uff1a");
int
length=input.nextInt();//\u8f93\u5165\u4e00\u4e2a\u6574\u6570
System.out.println("\u8f93\u5165\u7684\u6574\u6570\u662f\uff1a"+length);}
}
\u5907\u6ce8\uff1aScanner\u51fd\u6570\u5c31\u662f\u7528\u6765\u8fdb\u884c\u8bed\u53e5\u8f93\u5165\u7684\uff0c\u4e0a\u9762\u4e3e\u4f8b\u7684\u662f\u6574\u6570\u7c7b\u578b\uff0c\u4e5f\u53ef\u4ee5\u7528\u4ee5\u4e0b\u8bed\u53e5\u201cString
length=input.next()\u201d\uff0c\u8f93\u5165\u7684\u5c31\u662f\u5b57\u7b26\u4e32\u7c7b\u578b\u7b49\u3002
\u6c42\u5404\u4f4d\u6570\u5b57\u4e4b\u548c\u7684\u7a0b\u5e8f\u5982\u4e0b\uff1a
import java.util.Scanner;
public class N {
public static int sumDigits(long n){
int sum=0;
while(n>0){
int m=(int)(n%10);
sum=sum+m;
n=n/10;
}
return sum;
}
public static void main(String[] args) {
try{
System.out.println("\u8bf7\u8f93\u5165\u6570\u5b57\uff1a");
Scanner sc=new Scanner(System.in);
long l=sc.nextLong();
System.out.println("\u8f93\u5165\u6570\u5b57\u7684\u5404\u4f4d\u6570\u4e4b\u548c\u4e3a"+sumDigits(l));
}catch(Exception e){
System.out.println("\u60a8\u8f93\u5165\u7684\u4e0d\u662f\u6570\u5b57\uff01");
}
}
}
\u8fd0\u884c\u7ed3\u679c\uff1a
\u8bf7\u8f93\u5165\u6570\u5b57\uff1a
49291
\u8f93\u5165\u6570\u5b57\u7684\u5404\u4f4d\u6570\u4e4b\u548c\u4e3a25
import java.io.InputStreamReader;
public class Test{
public static void main(String[] args){
int num ;
String str ;
BufferedReader brd=new BufferedReader(new InputStreamReader(System.in)) ;
while(true)
{
System.out.print("请输入数字:") ;
try
{
str=brd.readLine() ;
num=Integer.parseInt(str) ;
break ;
}
catch(Exception e)
{
System.out.println("对不起，只能输入整数，请重新输入。") ;
}
}
System.out.println("你输入的整数是: "+num) ;
}
}
要输出的是整数，当然要来个判断如果输入的不是时就重新提示输入的说。
首先需要用到Scanner 类，所以要在最开始import java.util.Scanner;
然后在需要用到的方法里面创建个Scanner 物体，Scanner sc = new Scanner(System.in);
然后就可以用Scanner的方法nextInt()了： sc.nextInt();
举例如下：
import java.util.Scanner; //import the Scanner class
public class sampleInput{
public static void main(String[] args){
Scanner sc = new Scanner(System.in); //create the new Scanner object sc
System.out.println("please input an integer");
int a = sc.nextInt(); //use the nextInt() method to read in
System.out.println("Thanks for your help!" + a); //print the input integer
}
}
import java.util.*
public class test{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
System.out.println("请输入一个整数： ");
int num = input.nextInt();
System.out.println("你输入的整数是："+num);
}
}
system.in InputStream
你可以用java I/O中的Stream类，也可以用scranner类。
相关知识：I/O和nI/o，包括InputStream与OutputStream。
贴上代码：
ublic class Test{
public static void main(String[] args){
int num ;
String str ;
BufferedReader brd=new BufferedReader(new InputStreamReader(System.in)) ;
while(true)
{
System.out.print("请输入数字:") ;
try
{
str=brd.readLine() ;
num=Integer.parseInt(str) ;
break ;
}
catch(Exception e)
{
System.out.println("对不起，只能输入整数，请重新输入。") ;
}
}
System.out.println("你输入的整数是: "+num) ;
}
}
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