repeating a program in java [closed]

问题

I've been trying to repeat this program, but when I do, I keep getting errors. I repeated it before, but it asked to repeat after every row of asterisks. This is what I have so far:

import java.util.Scanner;

public class Pyramid 
{

//Displaying a Pyramid
public static void main(String[] args) 
{
  Scanner scanner = new Scanner(System.in);
  //Get user input = number of rows to print in a pyramid
  System.out.print("Enter an integer for the number of rows: ");
  int userInput = scanner.nextInt();
  scanner.close();

  int myLevel;
  int i, j , k;

  myLevel = userInput;

  for (i = 1; i <= myLevel; i++) {

  for (k =1; k <= myLevel-i; k++)

  System.out.print(" ");

  for (j = k+1; j <=myLevel; j++) 

  System.out.print( "*");
  for(int l=myLevel;l>k-1;l--)
  System.out.print( "*");

  System.out.println("");
   System.out.println("You want to continue : (Y/N) ");
    } while("Y".equalsIgnoreCase(scanner.next().trim()));
  }

}

回答1:

I am guessing that you want to repeat the above logic - right?

If this is the case then do not close your scanner

Also your while is wrongly formatted.

while("Y".equalsIgnoreCase(scanner.next().trim()));

Having the ; on the end will cause an endless loop in this case.

try

private static void myMethod(Scanner scanner) {
      //Get user input = number of rows to print in a pyramid
      System.out.print("Enter an integer for the number of rows: ");
      int userInput = scanner.nextInt();

      int myLevel;
      int i, j , k;

      myLevel = userInput;

      for (i = 1; i <= myLevel; i++) {

      for (k =1; k <= myLevel-i; k++)

      System.out.print(" ");

      for (j = k+1; j <=myLevel; j++) 

      System.out.print( "*");
      for(int l=myLevel;l>k-1;l--)
      System.out.print( "*");

      System.out.println("");

}

and

call it like

    Scanner scanner = new Scanner(System.in);

    do {
        myMethod (scanner);
        System.out.println("You want to continue : (Y/N) ");
    } while("Y".equalsIgnoreCase(scanner.next().trim()));   

    scanner.close ();

回答2:

You have an empty while statement at the end of code. You're trying to read input that doesn't exist. You need to encapsulate the entire program in a loop. You don't need to loop until there is input.

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



do{
          //Get user input = number of rows to print in a pyramid
          System.out.print("Enter an integer for the number of rows: ");
          int userInput = scanner.nextInt();

          int myLevel;
          int i, j , k;

          myLevel = userInput;

          for (i = 1; i <= myLevel; i++) {

          for (k =1; k <= myLevel-i; k++)

          System.out.print(" ");

          for (j = k+1; j <=myLevel; j++) 

          System.out.print( "*");
          for(int l=myLevel;l>k-1;l--)
          System.out.print( "*");

          System.out.println("");
            } 
          System.out.println("You want to continue : (Y/N) ");
          } while("Y".equalsIgnoreCase(scanner.next().trim()));
    }

You also close the scanner, so you can't re-use it.

来源：https://stackoverflow.com/questions/25276548/repeating-a-program-in-java

标签

java

repeat