在java中打印用户输入字符串的每三个字符

Question

使用For-Loop帮我编写一个程序,打印用户输入字符串的每三个字符.未显示的字符将打印为下划线.该程序的示例运行可能如下所示:

输入一个字符串:君士坦丁堡

C _ _ s _ _ n _ _ n _ _ l _

mycode的:

public class Ex02ForLoop {
public static void main(String[] args) {
    //name of the scanner    
    Scanner scanner = new Scanner(System.in);

    //initialize variable
    String userInput = "";

    //asking to enter a string
    System.out.print("Enter a string: ");

    //read and store user input
    userInput = scanner.next();

    //using For-Loop displaying in console every third character
    for (int i = 0; i <= userInput.length(); i+=3)
    {   
        System.out.print(userInput.charAt(i) + " _ _ ");    
    }
    scanner.close();
}}

但我的输出是:C _ _ s _ _ n _ _ n _ _ l _ _需要做一些事情才能把正确数量的下划线谢谢

Answer 1

用这个:

for (int i = 0; i < userInput.length(); i++)
{
    System.out.print(i % 3 == 0 ? userInput.charAt(i) : "_");
}