我在 Pattern.compile() 和 .matcher() 中传递变量但没有获得所需的输出

Question

我编写了一个程序，要求用户提供目标字符串和要在其中搜索的模式。它旨在找到匹配模式的位置以及它在目标字符串中出现的次数。但它总是显示没有找到模式，即使模式存在于目标字符串中。我已经为它写了一个函数searchPattern()。

    import java.util.Scanner;
    import java.util.regex.Matcher;
    import java.util.regex.Pattern;

    public class Main
    {
        private static Scanner sc = new Scanner(System.in);
        public static void main(String[] args)
        {

            String pattern,target;
            System.out.println("Enter Target String: ");
            pattern = sc.nextLine();
            System.out.println("Enter pattern to be searched: ");
            target = sc.nextLine();
            searchPattern(pattern,target);
        }
        public static void searchPattern(String pattern,String target)
        {
            Pattern p = Pattern.compile(pattern);
            Matcher m = p.matcher(target);
            int count = 0;
            //if(!m.find())return;
            while (m.find())
            {
                count ++;
                System.out.println(m.start() + "--" + m.end() + "--" + m.group());
            }
            if (count == 0)
                System.out.println("Your pattern was not found in the target string");
            else
                System.out.println("Total occurrences of 'ab' are" + count);

        }
    }

它给出以下输出：

Enter Target String: 
ababbab
Enter pattern to be searched: 
ab
Your pattern was not found in the target string

即使 'ab' 出现在目标字符串中，为什么此代码不起作用

Answer 1

您将目标和模式存储在错误的变量中

private static Scanner sc = new Scanner(System.in);

public static void main(String[] args) {

    String pattern, target;
    System.out.println("Enter Target String: ");
    target = sc.nextLine();
    System.out.println("Enter pattern to be searched: ");
    pattern = sc.nextLine();
    searchPattern(pattern, target);
}

public static void searchPattern(String pattern, String target) {
    Pattern p = Pattern.compile(pattern);
    Matcher m = p.matcher(target);
    int count = 0;
    while (m.find()) {
        count++;
        System.out.println(m.start() + "--" + m.end() + "--" + m.group());
    }
    if (count == 0) {
        System.out.println("Your pattern was not found in the target string");
    } else {
        System.out.println("Total occurrences of " + pattern + " are" + count);
    }
}

我在 Pattern.compile() 和 .matcher() 中传递变量但没有获得所需的输出

I am passing variables in Pattern.compile() and .matcher() but not getting required output

java

regex

pattern-matching

java.util.scanner