System.out.println（）在while循环中打印两次

Question

I created a while-loop to create a menu for my program, it will keep looping until the user types 'Quit' into the console. My problem is that whenever I enter 'Transfer' into the console the if statement runs perfectly but when it goes back to the start of the loop the System.out.println(); message prints twice instead of once. This doesn't happen with any of the other options.

Code:

int x = 0;
while(x != 1) {
    System.out.println("To transfer funds, please type 'Transfer'\n" //Typical message
                + "To list recent transactions, please type 'Recent'\n"
                + "To display account details, please type 'Details'\n"
                + "To quit the application, please type 'Quit'");

    String Option1 = "Transfer"; //Variables
    String Option2 = "Recent"; 
    String Option3 = "Details";
    String Option4 = "Quit";
    String Menu = ConsoleInput.nextLine();

    if (Menu.equals(Option1)) {
            //Statements
    } else if(Menu.equals(Option2)){
            //Statements
    } else if(Menu.equals(Option3)){
            //Statements
    } else if(Menu.equals(Option4)){
            //End statement
            x++;
    }
}

EDIT: Some of you are commenting about the increment of x in the last else statement and saying that it should be put outside the else statement. It's there because when the user types 'Quit' into the console it will exit the loop, if it was put outside the else statement then the user won't be able to access the other options.

EDIT 2 (SOLUTION): I finally fixed the problem. Turns out it was a scanner statement within the if-statement. I should have shown the full code for you all to see but I thought it was just the if-else-statements themselves.

Answer 1

Several things to look out for:

1. You should probably Menu.equalsIgnoreCase(Option1) etc.
2. YOu should put the increment of x right after the while loop. You are never incrementing x unless you type End.

I think you really want something more like

private static String[] options = {"Transfer","Recent","Details","Quit"};
private static int C_Transfer = 0;
private static int C_Recent = 1;
private static int C_Details = 2;
private static int C_Quit = 3;
private static int[] optionCase = {C_Transfer, C_Recent, C_Details,C_Quit);
private String menu;
private String message = "To transfer funds, please type 'Transfer'\n" //Typical message
                + "To list recent transactions, please type 'Recent'\n"
                + "To display account details, please type 'Details'\n"
                + "To quit the application, please type 'Quit'"

System.out.println(message);
menu = ConsoleInput.nextLine()
while (!menu.equalsIgnoreCase(options[C_Quit]) {
    int case = -1;
    for (int i=0, i < options.length; i++) {
      if (menu.equalsEgnoreCase(options[i]) {
          case = i;
          break;
      }
      switch (case) 
        case C_Transfer: {
           break;
        } 
        case C_Transfer: {
           break;
        } 
        case C_Transfer: {
           break;
        } 
        case C_Transfer: {
           break;
        }
        default: { 
           System.out.println(message);
        }
        Menu = ConsoleInput.nextLine();
     }
}

Answer 2

This only happen on Transfer option right? Could you show the code for Transfer options? probably there's instruction to print the message over there, so you got the message printed twice when loop is start over again.

add: based on your 'transfer code'. It seems the problem is related with missuse of java.util.Scanner but I myself not sure about this utility class. But the modified code below is work for me:

public static void main(String[] args){
        java.util.Scanner ConsoleInput=new java.util.Scanner(System.in);
        String Menu;
        String message="To transfer funds, please type 'Transfer'\n" //Typical message
                + "To list recent transactions, please type 'Recent'\n"
                + "To display account details, please type 'Details'\n"
                + "To quit the application, please type 'Quit'";
        System.out.println(message);
                String Option1 = "Transfer"; //Variables
        String Option2 = "Recent"; 
        String Option3 = "Details";
        String Option4 = "Quit";
        while(!((Menu=ConsoleInput.nextLine()).equalsIgnoreCase(Option4))){
            if(Menu.equalsIgnoreCase(Option1)){
                System.out.println("You have selected transfer");
                System.out.println("How much would you like to transfer?");
                float deduction;
                float total = 2500;
                deduction = ConsoleInput.nextFloat();
                total = total - deduction;
                System.out.println("£" + total + " left in account. Transaction recorded.");
                //Fileoutput.println(sf.format(date) + " - £" + deduction + " taken from account. £" + total + " left in account.\n");  
                System.out.println(message);
            }else if(Menu.equalsIgnoreCase(Option2)){
                System.out.println("here is your balance...blah, blah, bbla\n");
                System.out.println(message);
            }else if(Menu.equalsIgnoreCase(Option3)){
                System.out.println("here is the details...blah, blah, bbla\n");
                System.out.println(message);
            }
        }
        System.out.println("Thanks");
    }