如何优化？

[Yancy_Xu]

上面的程序如何优化成，当在键盘中输入除数字以外的其他字符时，提示输入有误，然后能够再次重新输入？

[执笔记忆的空白]

写个循环，数字正则表达式为条件，错误了循环，正确了跳出 数字表达式：^[0-9]*$

[li4c]

package http.hello;

import java.util.Arrays;
import java.util.Scanner;


public class Demo5 {

	public static void fuck(String str){
		int oddNum =0;
		int evenNum = 0;
		for(int i = 0 ; i < str.length() ; i++){
			char c = str.charAt(i);
			int n = (int)c - 48;
			if(n % 2 ==0){
				evenNum++;
				continue;
			}
			oddNum++;
		}
		System.out.printf("奇数的个数是:%d\n偶数的个数是:%d\n",oddNum,evenNum);
	}
	public static void main(String []args){
		Scanner input = new Scanner(System.in);
		input.useDelimiter("\n");
		while(input.hasNextLine()){
			String str = input.nextLine();
			fuck(str);
		}
	}
}

[赵4老师]

过早的优化是万恶之源！

[老鼠拧刀满街找猫]

package com.shadowOfCode.demo1;

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class Number {

	public static void main(String[] args) {
		
		
		Scanner in=null;
		String str="";
		System.out.print("请输入:");
		int oddNumberCount=0,evenNumberCount=0;
		StringBuffer oddStr=new StringBuffer(100);
		StringBuffer evenStr=new StringBuffer(100);
		String[] arr=null;
		while(true){
			in=new Scanner(System.in);
			str=in.nextLine();
			if(!isNumber(str)){
				System.out.println("您输入有误，请重输！\n");
				continue;
			}
			System.out.println("您输入的数:"+str);
			arr=str.split(" ");
			for(String num:arr){
				if(num==null){
					continue;
				}
				boolean isOdd=isOddNumber(Integer.parseInt(num));
				if(isOdd){
					oddNumberCount++;
					oddStr.append(num+"\t");
				}else{
					evenNumberCount++;
					evenStr.append(num+"\t");
				}
			}
			//打印结果
			display(evenNumberCount, oddNumberCount, evenStr, oddStr);
			//归零
			evenNumberCount=0;
			oddNumberCount=0;
			evenStr.setLength(0);
			oddStr.setLength(0);
			
			System.out.println("是否继续?Y/N");
			if(in.nextLine().equalsIgnoreCase("n")){
				System.out.println("已结束！");
				return;
			}
			System.out.print("请输入:");
		}
		
	}
	
	/**
	 * 判断奇数（包括正负奇数）
	 * @param num
	 * @return
	 */
	public static boolean isOddNumber(int num){
		return (num&1)!=0;
	}
	
	public static void display(int evenNumberCount,int oddNumberCount,StringBuffer evenStr,StringBuffer oddStr){
		System.out.println("偶数个数为:"+evenNumberCount+"\t分别为:"+evenStr+"\n");
		System.out.println("奇数个数为:"+oddNumberCount+"\t分别为:"+oddStr+"\n");
	}
	
	public static boolean isNumber(String str){
		 String patternStr = "[\\d\\s ]+"; 
		 Matcher meq = Pattern.compile(patternStr).matcher(str);  
		 if(meq.matches()){   
			 return true; 
		}
		 return false;
	}

}

[老鼠拧刀满街找猫]

30行改为num.isEmpty()

package com.shadowOfCode.demo1;

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class Number {

	public static void main(String[] args) {
		
		
		Scanner in=null;
		String str="";
		System.out.print("请输入:");
		int oddNumberCount=0,evenNumberCount=0;
		StringBuffer oddStr=new StringBuffer(100);
		StringBuffer evenStr=new StringBuffer(100);
		String[] arr=null;
		while(true){
			in=new Scanner(System.in);
			str=in.nextLine();
			if(!isNumber(str)){
				System.out.println("您输入有误，请重输！\n");
				continue;
			}
			System.out.println("您输入的数:"+str);
			arr=str.split(" ");
			for(String num:arr){
				if(num.isEmpty()){
					continue;
				}
				boolean isOdd=isOddNumber(Integer.parseInt(num));
				if(isOdd){
					oddNumberCount++;
					oddStr.append(num+"\t");
				}else{
					evenNumberCount++;
					evenStr.append(num+"\t");
				}
			}
			//打印结果
			display(evenNumberCount, oddNumberCount, evenStr, oddStr);
			//归零
			evenNumberCount=0;
			oddNumberCount=0;
			evenStr.setLength(0);
			oddStr.setLength(0);
			
			System.out.println("是否继续?Y/N");
			if(in.nextLine().equalsIgnoreCase("n")){
				System.out.println("已结束！");
				return;
			}
			System.out.print("请输入:");
		}
		
	}
	
	/**
	 * 判断奇数（包括正负奇数）
	 * @param num
	 * @return
	 */
	public static boolean isOddNumber(int num){
		return (num&1)!=0;
	}
	
	public static void display(int evenNumberCount,int oddNumberCount,StringBuffer evenStr,StringBuffer oddStr){
		System.out.println("偶数个数为:"+evenNumberCount+"\t分别为:"+evenStr+"\n");
		System.out.println("奇数个数为:"+oddNumberCount+"\t分别为:"+oddStr+"\n");
	}
	
	public static boolean isNumber(String str){
		 String patternStr = "[\\d\\s ]+"; 
		 Matcher meq = Pattern.compile(patternStr).matcher(str);  
		 if(meq.matches()){   
			 return true; 
		}
		 return false;
	}

}

[rickylin86]

import java.util.Scanner;

public class Test{
	public static void main(String[] args){
		System.out.println("请输入一行数字:");
		Scanner keyboard = new Scanner(System.in);
		String content = null;
		while(!((content = keyboard.nextLine()).matches("^\\d+$"))){
			System.out.println("输入有误,请重新输入一行数字:");
		}
		int result_even = content.length() - content.replaceAll("[02468]","").length();
		int result_odd = content.length() - result_even;
		System.out.printf("你输入的内容:'%s',其中奇数:%d个,偶数%d个%n",content,result_odd,result_even);
	}
}