在Java中使用charAt

Question

This is my assignment:

Write a program where the user enters a string, and the program echoes it to the monitor with one character per line:

C:\>java LinePerChar
Enter a string:
Octopus

O
c
t
o
p
u
s

I have tried, but I'm getting some compilation errors. Here's my code:

import java.util.*;

class CharactorEcho{
    public static void main(String args []){

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter a string :");

        try {
            String inputString = sc.nextLine();
            for(int i=0; i < sc.length(); i++) {
                char c = inputString.charAt(i);
                System.out.println("" + c);
            }
        } catch(IOException e) {

        }
    }
}

Answer 1

In your loop, you should be looping over the length of the String that you get from the Scanner.nextLine , not the scanner itself.

for(int i=0; i<inputString.length(); i++){

If you want the input to be echoed with each character on the same line, use System.out.print instead of println .

Answer 2

Two Issues:

Change for(int i=0; i<sc.length(); i++){ to for(int i=0; i<inputString.length(); i++){

You care comparing against the scanner and not the input string.

Also, please try catching

   java.util.NoSuchElementException
   java.lang.IllegalStateException

in place of IOException , as your statement sc.nextLine() with throws NoSuchElementException and IllegalStateException , not IOException .

Make sure you add the related import statements.

Answer 3

You need to import IOException . Add this line to the top of your code, just after the package line if you have one:

import java.io.IOException;

Also, you're asking sc for a length instead of the string, so change your for to this:

for(int i = 0; i < inputString.length(); i++) {

Really though, you shouldn't be catching IOException . In fact, your code will never throw an exception. This is really all you need:

public static void main(String args []){

    Scanner sc = new Scanner(System.in);

    System.out.println("Enter a string :");

    String inputString = sc.nextLine();
    for(int i=0; i < sc.length(); i++) {
        char c = inputString.charAt(i);
        System.out.println("" + c);
    }
}

Calling nextLine on a Scanner made with System.in will only throw an exception if System.in isn't accessible, and it won't even be an IOException , so don't worry about it.

One final observation, you don't need to do "" + c in your println . System.out has a println method specifically for char , so you can just call:

System.out.println(c);