BlueJ-我的程序编译没有错误，但是没有运行

Question

Hello I'm having problems with a program that's supposed to take in a string and then capitalize the first letters of each word using the Character Wrapper class.

 import java.util.*;
public class wrapper
{
    public static void main(String[] args)
    {
        Scanner input= new Scanner(System.in);
        String s1;
        s1=input.nextLine();
        s1= s1.trim();
        int howLong= s1.length();
        int i;
        int counter=0;
        char cho;
        for(counter=1; counter<= howLong+1; counter++)
        {
            cho=s1.charAt(counter);
            if(Character.isLetter (cho) && ! Character.isLetter(s1.charAt(counter-1)))
            {
                System.out.print( Character.toUpperCase(cho) );
            }
            else
            {
                System.out.print(cho);
            }
            System.out.println();
        }

        }
    }

That's the program so far, but while it compiles with no errors according to BlueJ, it doesn't run. Any help as to why this is happening would be great.

Edit: Changed the program to what I believe would make it not just print out the spaces that the char variable was initialized to, but it still does not run. Maybe there's something wrong with the loop?

Answer 1

The reason your program compiles but doesn't run is because of the line s1=input.nextLine(); . At this line, the program is waiting for input from the user to use as the string s1 , but does not show the terminal in order for the user to give such input. A way you can get around this is to force the terminal to show itself before that line. I would recommend putting something like

System.out.println("Enter input:");

before the line, so that the terminal will show itself & the user can enter input into it. From there, you can work on the program like you would normally.