Question

我必须创建一个程序，该程序使用3个字符串并按字典顺序对其进行排序。我发现为此必须使用compareTo()方法，问题是当我尝试执行if语句时，我看到它们是int而不是字符串，而且我什至不知道如何显示哪个是最小的一种，因为有很多不同的选择。有没有更简单的方法可以使用该方法（不允许使用数组或任何其他方法）？

import java.util.Scanner;
public class SetAQuestion2
{
    public static void main (String[] args)
    {
        Scanner scan = new Scanner (System.in);
        String first, second, third;

        System.out.print("Type three words: ");
        first = scan.next();
        second = scan.next();
        third = scan.next();

        int oneA = (first. compareTo (second));
        int oneB = (first.compareTo (third));

        int secondA = (second. compareTo (first));
        int secondB = (second.compareTo(third));

        int thirdA = (third.compareTo(first));
        int thirdB = (first.compareTo (second));

        System.out.println("The smallest word lexicographically is ");
    }
}

Answer 1

如果只想使用compareTo()和简单的if/else语句，则可以设置另一个字符串变量并比较单词。例如：

String first, second, third, result;
System.out.println("Type three words: ");
first = scan.next();
second = scan.next();
third = scan.next();

if (first.compareTo(second) > 0)
    result = second;
else
    result = first;

if (result.compareTo(third) > 0)
    result = third;
System.out.println("The smallest word lexicographically is " + result);

您也可以使用三元表达式代替if语句：

result = first.compareTo(second) > 0 ? (second.compareTo(third) > 0 ? third : second) : (first.compareTo(third) > 0 ? third : first);

我还建议您在使用扫描仪时使用try-with-resources，以使其自动关闭，因此：

try (Scanner scan = new Scanner(System.in)) {
    // rest of the code here
}

编辑：

正如安迪·特纳（Andy Turner）在其评论中所述，如果从System.in中读取扫描仪，则不必关闭扫描仪或使用try-with-resources。仅当它从文件读取时才这样做。

Answer 2

您说您必须按字典顺序排序 3个字符串。我的意思是，您必须按从低到高的顺序输出3个字符串，而不仅仅是找到最小的字符串。

下面是一些Java代码，以最少的比较来说明执行此操作所需的逻辑：

public static void main(String[] args)
{
    String[][] tests = {
            {"a", "b", "c"},
            {"a", "c", "b"},
            {"b", "a", "c"},
            {"b", "c", "a"},
            {"c", "a", "b"},
            {"c", "b", "a"},
            };

    for(String[] s : tests)
    {
        order(s[0], s[1], s[2]);
    }
}

static void order(String first, String second, String third)
{
    int firstSecond = first.compareTo(second);
    int firstThird = first.compareTo(third);
    int secondThird = second.compareTo(third);

    if(firstSecond < 0)
    {
        if(firstThird < 0)
        {
            if(secondThird < 0)
            {
                print(first, second, third);
            }
            else
            {
                print(first, third, second);
            }
        }
        else
        {
            print(third, first, second);
        }
    }
    else if(secondThird < 0)
    {
        if(firstThird < 0)
        {
            print(second, first, third);
        }
        else
        {
            print(second, third, first);
        }
    }
    else
    {
        print(third, second, first);
    }
}

private static void print(String... arr)
{
    System.out.println(Arrays.toString(arr));
}

输出：

[a, b, c]
[a, b, c]
[a, b, c]
[a, b, c]
[a, b, c]
[a, b, c]

从3中查找字典序最小的字符串

2 个答案: