java - 输入并指定要打印的字符以及每行要打印的字符数

Question

我试图允许用户指定要打印的字符以及每行要打印的字符数。

我尝试使用以下类和方法来实现此目标:

import java.util.Scanner;

public class test3char {

    /**
     * @param args
     */
    public static void main(String[] args) {
        //insert the character 
        System.out.println("insert character");
        Scanner keyboard = new Scanner(System.in);
        String str= keyboard.nextLine();
        //insert the time you would like to print the character 
        System.out.println("insert the number of times you would like to print the car");
        int n = keyboard.nextInt();
        keyboard.close();

        // loop 
        int i;
        for (i=1;i<=n;i=i+1) {
            System.out.print(str.charAt(i));
        }

    }

}

第 17 行出现以下错误:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 1
    at java.lang.String.charAt(Unknown Source)
    at test3char.main(test3char.java:17)

如何修复此循环，以便在同一行上打印 n 次用户输入的字符串。

Answer 1

您走在正确的轨道上，但不是使用 charAt在 for 循环中，尝试使用 charAt 类似的方法早些时候:

import java.util.Scanner;

class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    System.out.print("Please enter the character you want repeated: ");
    char character = scanner.next().charAt(0);

    System.out.print("Please enter the number of times you would like to print the character:");
    int number = scanner.nextInt();

    for(int i = 0; i < number; i++) {
      System.out.print(character);
    }
  }
}

用法示例:

Please enter the character you want repeated:  a
Please enter the number of times you would like to print the character: 5
aaaaa