java - 执行 while 循环以显示菜单

Question

我已经用 do~while(true) 创建了我的菜单；但是每次用户输入一个数字时，它不会运行程序，而是再次显示菜单!你怎么看？

//我的主要方法

public static void main(String[] args) {

    DataReader reader = new DataReader(); // The reader is used to read data from a file

    // Load data from the file
    if(reader.loadData(args[0])) {          // The filename is entered using a command-line argument

        vehicles= reader.getVehicleData(); // Store the arrays of Vehicle

        // Display how many shapes were read from the file
        System.out.println("Successfully loaded " + vehicles[0].getCount() + 
                           " vehicles from the selected data file!");
        displayMenu();
    }
}

//显示菜单方法

private static void displayMenu() {
    Scanner input = new Scanner(System.in);

    do {
        System.out.println("\n\n          Car Sales Menu");
        System.out.println("--------------------------------------");
        System.out.println("1 - Sort vehicles by owner's Last Name");
        System.out.println("2 - Sort vehicles by vehicle Model");
        System.out.println("3 - Sort vehicles by vehicle Cost\n");
        System.out.println("4 - List All Vehicles");
        System.out.println("5 - List All Cars");
        System.out.println("6 - List American Cars Only (Formal)");
        System.out.println("7 - List Foreign Cars only (Formal)");
        System.out.println("8 - List All Trucks");
        System.out.println("9 - List All Bicycles");
        System.out.print("\nSelect a Menu Option: ");
        getInput(input.next()); // Get user input from the keyboard 
    }
    while(true); // Display the menu until the user closes the program
}

//获取输入法

private static void getInput(String input) {
    switch(Convert.toInteger(input)) {
        case 1: // Sort Vehicles by Owner's Last Name
            Array.sortByOwnerName(vehicles);
            break;
        case 2: // Sort Vehicles by Vehicle Make & Model
            Array.sortByVehicleMakeModel(vehicles);
            break;
        case 3: // Sort Vehicles by Vehicle Cost
            Array.sortByVehicleCost(vehicles);
            break;
        case 4: // List All Vehicles
            displayVehicleData(0);
            break;

        default:
            System.out.print("The entered value is unrecognized!");
            break;
    }
}

Answer 1

因为你有 while(true);，这意味着菜单将处于无限循环中，直到调用 break。

尝试做类似的事情:

 do {
        System.out.println("\n\n          Car Sales Menu");
        System.out.println("--------------------------------------");
        System.out.println("1 - Sort vehicles by owner's Last Name");
        System.out.println("2 - Sort vehicles by vehicle Model");
        System.out.println("3 - Sort vehicles by vehicle Cost\n");
        System.out.println("4 - List All Vehicles");
        System.out.println("5 - List All Cars");
        System.out.println("6 - List American Cars Only (Formal)");
        System.out.println("7 - List Foreign Cars only (Formal)");
        System.out.println("8 - List All Trucks");
        System.out.println("9 - List All Bicycles");
        System.out.print("\nSelect a Menu Option: ");
    try {
        int input = Integer.parseInt(getInput(input.next())); // Get user input from the keyboard 


        switch (input) {
        case 1:  // do something
                 break;
        case 2:  // do something
                 break;
        ...
       }
      } catch (NumberFormatException e) { ... }

    }
    while(true); // Display the menu until the user closes the program

您可以使用 switch处理输入，并根据输入执行相应的操作。