Java有关判断的问题

1. 向用户请求输入。
2. 确定输入的数据类型是byte、short、int、long、float和/或double。
3. 程序应该一直等待用户输入，直到用户输入“退出”(忽略大小写)。
   

   

import java.util.Scanner;

import System;

public class test {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String str = sc.nextLine();
        sc.close();
        String[] strs = str.split(" ");
        for (int i = 0; i < strs.length; i++) {
            try {
                Integer tmp = Integer.valueOf(strs[i]);
                if (tmp >= 0 && tmp <= 255) {
                    java.lang.System.out.println(strs[i] + " can be converted into a type byte!");
                } else {
                    java.lang.System.out.println(strs[i] + " cannot be converted into a type byte!");
                }
            } catch (Exception e) {
                java.lang.System.out.println(strs[i] + " cannot be converted into a type byte!");
            }

            try {
                Short tmp = Short.parseShort(strs[i]);
                java.lang.System.out.println(strs[i] + " can be converted into a type short!");
            } catch (Exception e) {
                java.lang.System.out.println(strs[i] + " cannot be converted into a type short!");
            }

            try {
                Integer tmp = Integer.valueOf(strs[i]);
                java.lang.System.out.println(strs[i] + " can be converted into a type int!");
            } catch (Exception e) {
                java.lang.System.out.println(strs[i] + " cannot be converted into a type int!");
            }

            try {
                Float tmp = Float.parseFloat(strs[i]);
                java.lang.System.out.println(strs[i] + " can be converted into a type float!");
            } catch (Exception e) {
                java.lang.System.out.println(strs[i] + " cannot be converted into a type float!");
            }

            try {
                Double tmp = Double.valueOf(strs[i]);
                java.lang.System.out.println(strs[i] + " can be converted into a type double!");
            } catch (Exception e) {
                java.lang.System.out.println(strs[i] + " cannot be converted into a type double!");
            }
        }
    }
}

目前没有想到直接用空格进行判断，我这里以换行符进行判断，你可以找一下如何以空格退出来替换 next()
代码

public static void main(String[] args)throws  Exception{
        InputStream in = System.in;
        Scanner sc = new Scanner(System.in);
        System.out.println("Example Input：");
        String string = sc.next();
        List<String> stringList = new ArrayList<>();
        while(!("退出".equals(string))){
            stringList.add(string);
            sc = new Scanner(System.in);
            string = sc.next();
        }
        System.out.println("Simple Output：");
        for (String str : stringList){
            try {
                Integer tmp = Integer.valueOf(str);
                if (tmp >= 0 && tmp <= 255) {
                    System.out.println(str + " can be converted into a type byte!");
                } else {
                    System.out.println(str + " cannot be converted into a type byte!");
                }
            } catch (Exception e) {
                System.out.println(str + " cannot be converted into a type byte!");
            }

            try {
                Short tmp = Short.parseShort(str);
                System.out.println(str + " can be converted into a type short!");
            } catch (Exception e) {
                System.out.println(str + " cannot be converted into a type short!");
            }

            try {
                Integer tmp = Integer.valueOf(str);
                System.out.println(str + " can be converted into a type int!");
            } catch (Exception e) {
                System.out.println(str + " cannot be converted into a type int!");
            }

            try {
                Float tmp = Float.parseFloat(str);
                System.out.println(str + " can be converted into a type float!");
            } catch (Exception e) {
                System.out.println(str + " cannot be converted into a type float!");
            }

            try {
                Double tmp = Double.valueOf(str);
                System.out.println(str + " can be converted into a type double!");
            } catch (Exception e) {
                System.out.println(str + " cannot be converted into a type double!");
            }
        }

    }

运行结果：

Example Input：
123
true
22.93
退出
Simple Output：
123 can be converted into a type byte!
123 can be converted into a type short!
123 can be converted into a type int!
123 can be converted into a type float!
123 can be converted into a type double!
true cannot be converted into a type byte!
true cannot be converted into a type short!
true cannot be converted into a type int!
true cannot be converted into a type float!
true cannot be converted into a type double!
22.93 cannot be converted into a type byte!
22.93 cannot be converted into a type short!
22.93 cannot be converted into a type int!
22.93 can be converted into a type float!
22.93 can be converted into a type double!

Process finished with exit code 0

希望对你有帮助^-^