Question

求一个if判断，若输入的是数字输出数字；若输入的是字符输出字符串

public class SystemIn {

private static double outputNum() {
Scanner scanner = new Scanner(System.in);
double n = scanner.nextDouble();
double b = 0.5;
n = Math.pow(n, b);
System.out.println(n);
return n;
}
private static String outputString() {
Scanner scanner = new Scanner(System.in);
String s = scanner.nextLine();
String str = s.concat("Java");
System.out.println(str);
return s;
}

public static void main(String[] args) {
if(......){ //想写一个判断，若输入的是数字执行outputNum；若输入的是字符执行outputString
outputString();
}
else{
outputNum();
}
}
}

Answer 1

import java.util.Scanner;
public class SystemIn {

private static double outputNum(double s) {
double b = 0.5;
double n = Math.pow(s, b);
System.out.println(n);
return n;
}
private static String outputString(String s) {
String str = s.concat(" Java");
System.out.println(str);
return s;
}

public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String s = scanner.next();
try{
double b = Double.parseDouble(s);
outputNum(b);
}catch(NumberFormatException ex){
outputString(s);
}
}
}

Answer 2

一楼回答的不错，就是利用异常