在java中怎样从键盘输入数字（新手问题） java中从控制台输入(要怎样才能规定只能输入数字呢)希望能...
JAVA\u600e\u4e48\u5199\uff1a\u63a5\u6536\u4ece\u952e\u76d8\u8f93\u5165\u7684\u5b57\u7b26\u4e32\u5e76\u6253\u5370\u51fa\u6765\uff1f\u65b0\u624b\u95ee\u9898\uff08\u975e\u8bda\u52ff\u6270\uff09Scanner scan = new Scanner(System.in);scan.nextLine();//\u63a5\u6536\u4e00\u884c\u5b57\u7b26\u4e32\uff0c\u4ee5\u56de\u8f66\u952e\u7ed3\u675f//\u5176\u4ed6\u7c7b\u578b\u7684\u8f93\u5165\uff0c\u53ef\u4ee5\u67e5\u770bscan\u5bf9\u8c61\u4e2d\u7684\u65b9\u6cd5scan.close();
public static void main(String[] args) {
/** \u5199\u4e00\u4e2a\u7a0b\u5e8f\uff1a\u4ece\u63a7\u5236\u53f0\u8f93\u5165\uff0c\u4f7f\u4e4b\u628a\u5b57\u7b26\u4e32\u7684\u6570\u5b57\u7ed9\u63d0\u70bc\u51fa\u6765
* \u5982\uff1a\u8f93\u5165\uff1a\u201cwa21ttw43p6ku5mm\u201d \u8f93\u51fa\uff1a214365 */
System.out.println("\u8bf7\u8f93\u5165\uff1a");
Scanner s = new Scanner(System.in);
String str = s.next();
String reg = "\\d";//\u6b63\u5219\u8868\u8fbe\u5f0f
StringBuffer result = new StringBuffer();
StringBuffer sb = new StringBuffer();
for(int i = 0;i < str.length();i++){
sb.append(str.charAt(i)).append("_");
}
String mes = sb.toString();
String[] data = mes.split("_");
for (String st : data) {
if(st.matches(reg)){
result.append(st);
}
}
System.out.println(result);
}
方便的从键盘输入数据:
使用方法举例: String s=Input.readString(); 读入字符串
int i=Input.readInt(); 读入整数
下面是java输入输出基本类Input类的源代码:
最后以从键盘输入10个整数为例说明之。
import java.io.*;
class Input
{static InputStreamReader in;
static BufferedReader reader;
static
{in=new InputStreamReader(System.in);
reader=new BufferedReader(in);
}
static String readString()
{String s="";
try
{ s=reader.readLine();
}
catch(IOException e)
{System.out.println(e);
System.exit(0);
}
return s;
}
static char readChar()
{char ch='a';
try
{
String s=readString();
ch=s.charAt(0);
}
catch(Exception e)
{System.out.println("输入的数据类型不对，程序将退出");
System.exit(0);
}
return ch;
}
static int readInt()
{String s=readString();
int i=0;
try{
i=Integer.parseInt(s);
}
catch(Exception e)
{System.out.println("输入的数据类型不对，程序将退出");
System.exit(0);
}
return i;
}
static double readDouble()
{String s=readString();
double d=0.0;
try
{d=Double.parseDouble(s);
}
catch(Exception e)
{System.out.println("输入的数据类型不对，程序将退出");
System.exit(0);
}
return d;
}
static float readFloat()
{
String s=readString();
float f=0.0f;
try
{
f=Float.parseFloat(s);
}
catch(Exception e)
{ System.out.println("输入的数据类型不对，程序将退出");
System.exit(0);
}
return f;
}
}
/*用法举例,从键盘输入十个整数:*/
class InoutData
{public static void main(String args[])
{ int a[]=new int[10];
for(int i=0;i<10;i++)
{ System.out.println("请输入第"+(i+1)+"个数:");
a[i]=Input.readInt();
}
for(int i=0;i<10;i++)
System.out.println("a["+i+"]="+a[i]);
}
}
以下的代码是你的版本，是可以执行并且成功的。
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);// 获取键盘输入
int a = sc.nextInt();
int b = sc.nextInt();
int c = sc.nextInt();
System.out.println("由大到小的顺序是：");
if (a < b)
if (b < c)
System.out.println(c + " " + b + " " + a);
else if (a < c)
System.out.println(b + " " + c + " " + a);
else
System.out.println(b + " " + a + " " + c);
else if (a < c)
System.out.println(c + " " + a + " " + b);
else if (b < c)
System.out.println(a + " " + c + " " + b);
else
System.out.println(a + " " + b + " " + c);
}
}
也可以用下面的，3个数的排序，可以用3目。
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);// 获取键盘输入
int a = sc.nextInt();
int b = sc.nextInt();
int c = sc.nextInt();
System.out.println("由大到小的顺序是：");
// 还可以这么做
System.out.println(a > b ? (b > c ? a + " " + b + " " + c : a > c ? a
+ " " + c + " " + b : c + " " + a + " " + b) : (c < a ? b + " "
+ c + " " + a : b > c ? b + " " + c + " " + a : c + " " + b
+ " " + a));
}
}
你的if else语句写得太乱了，基本上按照你的意思来写的 OK了
import java.util.*;
class Order1
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);//获取键盘输入
int a=sc.nextInt();
int b=sc.nextInt();
int c=sc.nextInt();
System.out.println("由大到小的顺序是：");
if(a>b && b>c)
System.out.println(a+">"+b+">"+c);
if(a>c && c>b)
System.out.println(a+">"+c+">"+b);
if(b>a && a>c)
System.out.println(b+">"+a+">"+c);
if(b>c && c>a)
System.out.println(b+">"+c+">"+a);
if(c>a && a>b)
System.out.println(c+">"+a+">"+b);
if(c>b && b>a)
System.out.println(c+">"+b+">"+a);
}
}
使用Scanner类
Scanner scanner = new Scanner(System.in);
使用BufferedReader类
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
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绛旓細Scanner input=new Scanner(System.in);System.out.println("杈撳叆绗竴涓暟:");double d1=input.nextDouble();System.out.println("杈撳叆绗簩涓暟:");double d2=input.nextDouble();System.out.println("杈撳叆杩愮畻绗﹀彿锛+-*/锛夛細");String s=input.next();if(s.length()!=1){ System.out....
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