Java哨兵循环，更清洁或更有组织的方式来做到这一点？

Question

我正在寻找一种更紧凑的方法来处理我的哨兵循环。我在这里的代码完全按照我的意图工作，但我很好奇是否有一种更简洁或更简洁的方法来做到这一点，而无需任何额外的循环或 if 语句。谢谢！

public void findSmallLarge()
{
    //declaring variable
    int maxValue = 0;
    int minValue = 0;
    int input = 0;
    boolean done = false;
    String sentinel;

    //Scanner object
    Scanner in = new Scanner(System.in);

    //loop asks user to input integers and will tell the user the minimum and maximum values, after the program quits.
    System.out.println("Please enter an integer, or press Q to quit");
    while (!done && in.hasNextInt())
    {           
        System.out.printf("Please enter an integer, or press Q to quit: ");
        input = in.nextInt();

        // if input is greater than the maxvalue, update the maxvalue.
        if (input > maxValue)
            {
            maxValue = input;
            }

        // if input is less than the minimum value, update the minimum value.
        if (input < minValue)
        {
            minValue = input;
        }

        // if the next input is not an int AND done is false, run the loop until an integer is entered.  If q/Q is entered, quit the program.
        if (!in.hasNextInt() && !done)
        {
        while (!in.hasNextInt() && !done)
        {
            sentinel = in.next();
            System.out.print("Please enter a valid integer, or press Q to quit: ");
            if (sentinel.charAt(0) == 'Q' || sentinel.charAt(0) == 'q')
            {
                System.out.println();
                System.out.println("You have quit the program");
                done = true;
                break;
            }
        }
        }
    }
    // Print the updated min and max values
    System.out.println("The Max value is: " + maxValue);
    System.out.println("The Minimum value is: " + minValue);
    System.out.println();

Answer 1

您可以使用 Math.min(int, int) 和 Math.max(int, int) 替换您的 input > maxValue 和 input < minValue 支票，如

maxValue = Math.max(maxValue, input);
minValue = Math.min(minValue, input);

你应该像这样声明它们

int maxValue = Integer.MIN_VALUE;
int minValue = Integer.MAX_VALUE;

至于你的 sentinel 循环，你可以使用

 if (Character.toUpperCase(sentinel.charAt(0)) == 'Q')

您也可以删除 done 布尔值，然后使用

System.exit(0);

Answer 2

我找到了我正在寻找的确切答案。我在上面发布的代码不断地询问用户输入，当输入错误（即不是整数）时，它会告诉用户他们的输入是错误的，当用户按下 Q 或 q 时，程序结束。我找到了我正在寻找的更直接的版本。

import java.util.Scanner;

public class NovLecture {

public static void main(String[] args) {



Scanner in = new Scanner(System.in);
boolean done = false;
System.out.println("Please enter an integer or press Q to quit");

// While done is not false, run this loop
while(!done)
{
    // if the next input is an int, do this, other wise continue to else
    if(in.hasNextInt())
    {
        int input = in.nextInt();

    } 
    // If input is anything other than an int, place the input into a string
    else 
    {
        String input =  in.next();

        // and if the input is equal to a q or Q, end the program
        // by setting done to true
        if (input.charAt(0) == 'q' || input.charAt(0) == 'Q')
        {
            done = true;
        } 

        //otherwise tell the user the input is bad and to try again, and flush the input.
        else
        {
                System.out.println("Bad input, please try again");
                in.next();

        }
    }
}
}

}