acm - JAVA如何判断 一个数是 整形还是浮点型

Answer 1

import java.io.IOException;
import java.util.Scanner;

public static void main(String[] args) throws IOException{
    System.out.println("input：");  
    Scanner sc = new Scanner(System.in);
    String input = sc.next();
    if (!input.matches("^[0-9]+([.]{0,1}[0-9]+){0,1}$")){
        System.out.println("this is not a number");   
    }else if (input.matches("^[0-9]+$")){
        System.out.print("this is a integer");
    }else {
        System.out.print("this is a double");
    } 
}

Answer 2

直接把你的输入值转成一个string然后调用string的contains（）方法看是否包含"."

Answer 3

import java.text.Format.Field;

public class zh {

public static void main(String[] args){
       
       int  i = 1;    //例如int
        String type = getTypeFromObj(i);
        System.out.println(type);//打印出int值 
}
    public static  String getTypeFromObj(Object o){
     
        //得到Object的所有属性，第一个就是类型type
        java.lang.reflect.Field[] fileds = o.getClass().getDeclaredFields();
        String type = null;
        int i;
        for(i=0;i<fileds.length;i++){ 
          type = ((java.lang.reflect.Field) fileds[i]).getType().toString(); 
          break;
        }    
        return type; 
      }

}