Question

我将如何继续此循环？我需要按Y继续循环，当我按N时它应该结束循环。当我按下不同的输入时，循环不会停止，直到我只按Y或N.我是初学者，谢谢你的帮助！

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Answer 1

您可以使用此代码

while(true){
//scan the choice then enter the loop 
while (!choice.equals("N")){
// you should use  "switch case".
}
if(choice.equals("N")){
     System.out.println("Thank you for using the program!") ;
     break;
}
}

你可以把它全部循环。

Answer 2

您应该使用'break'语句

您的代码：

else if (option.equals ("N") )
{
    System.out.println("Thank you for using the program!") ;

}

更新的代码：

  else if (option.equals ("N") )
{
    System.out.println("Thank you for using the program!") ;
    break;
}

同样，您可以在代码的“else”语句中使用它...

Answer 3

我建议您在其他编程实践中研究抽象，以便您的代码更易读，更容易理解。但这是一个循环过程的简单方法（取决于用户输入（选择））。

String choice;
while (!(choice = readLine()).equals("N")){
  if (choice == "Y"){
    //Do the process you wish to loop
  } else{
    System.out.println("Invalid input.");
  }
}
private String readLine(){
  System.out.println("Enter Y to enter another number.\nEnter N to exit.");
  return input.nextLine();
}

Answer 4

试试这个程序：

import java.util.Scanner;

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

        Scanner input = new Scanner(System.in);
        int S1 = 0;
        String option = null;
        int[][] MT = new int[S1][S1];
        System.out.println("Welcome To The Multiplication Table Program!");
        boolean validInput = true;
        boolean exitOuterLoop = false;
        do {
            validInput = true; // to reset from second time onwards
            System.out.print("Input a number from 1-20: ");
            String Num = input.nextLine();

            if (Num.equals("1")) {
                S1 = 1;
                MT = timesTable(1, 1);
            } else if (Num.equals("2")) {
                S1 = 2;
                MT = timesTable(2, 2);
            } else if (Num.equals("3")) {
                S1 = 3;
                MT = timesTable(3, 3);
            } else if (Num.equals("4")) {
                S1 = 2;
                MT = timesTable(4, 4);
            } else if (Num.equals("5")) {
                S1 = 2;
                MT = timesTable(5, 5);
            } else if (Num.equals("6")) {
                S1 = 2;
                MT = timesTable(6, 6);
            } else if (Num.equals("7")) {
                S1 = 2;
                MT = timesTable(7, 7);
            } else if (Num.equals("8")) {
                S1 = 2;
                MT = timesTable(8, 8);
            } else if (Num.equals("9")) {
                S1 = 2;
                MT = timesTable(9, 9);
            } else if (Num.equals("10")) {
                S1 = 2;
                MT = timesTable(10, 10);
            } else if (Num.equals("11")) {
                S1 = 2;
                MT = timesTable(11, 11);
            } else if (Num.equals("12")) {
                S1 = 2;
                MT = timesTable(12, 12);
            } else if (Num.equals("13")) {
                S1 = 2;
                MT = timesTable(13, 13);
            } else if (Num.equals("14")) {
                S1 = 2;
                MT = timesTable(14, 14);
            } else if (Num.equals("15")) {
                S1 = 2;
                MT = timesTable(15, 15);
            } else if (Num.equals("16")) {
                S1 = 2;
                MT = timesTable(16, 16);
            } else if (Num.equals("17")) {
                S1 = 2;
                MT = timesTable(17, 17);
            } else if (Num.equals("18")) {
                S1 = 2;
                MT = timesTable(18, 18);
            } else if (Num.equals("19")) {
                S1 = 2;
                MT = timesTable(19, 19);
            } else if (Num.equals("20")) {
                S1 = 2;
                MT = timesTable(20, 20);
            } else {
                System.out.println("Error! Input a number from 1-20 only!");
                validInput = false;
            }
            if (validInput) {

                for (int row = 0; row < MT.length; row++) {
                    for (int column = 0; column < MT[row].length; column++) {
                        System.out.printf("%3d ", MT[row][column]);
                    }
                    System.out.println();

                }
                System.out
                        .println("Enter 'Y' to enter another number \nEnter 'N' to exit ");
                do {
                    System.out.print("Y/N: ");
                    option = input.nextLine();
                    if (option.equalsIgnoreCase("Y")) {
                        S1 = 0;
                        MT = timesTable(0, 0);
                    } else if (option.equalsIgnoreCase("N")) {
                        System.out.println("Thank you for using the program!");
                        exitOuterLoop = true;
                    }

                    else
                        System.out.println("Enter Y or N only!");

                } while (!option.equalsIgnoreCase("Y")
                        && !option.equalsIgnoreCase("N"));
            }

        } while (!exitOuterLoop);

    }

    public static int[][] timesTable(int r, int c) {
        int[][] TT = new int[r][c];
        for (int row = 0; row < TT.length; row++) {
            for (int column = 0; column < TT[row].length; column++) {
                TT[row][column] = (row + 1) * (column + 1);
            }

        }
        return TT;
    }

}

注意：我在这里给出的解决方案是针对您遇到的问题。有更好的方法来解决这个问题。

double Do While循环

4 个答案: