How Can I Implement a Java Comparator with SQL's `LIKE` Operator Functionality?

Implementing a Java Comparator with SQL's 'LIKE' Operator Semantics

In SQL, the 'LIKE' operator is widely used for matching strings based on specific patterns. To achieve similar functionality in Java, we can create a customized comparator that exhibits the same behavior.

Solution Using Regular Expressions

Java's regular expressions can be employed to emulate the 'LIKE' operator. By utilizing the wildcard character '*', any sequence of characters can be matched. For instance, the following regular expression will match any string containing 'ital' anywhere:

.*ital.*

Similarly, a single character placeholder can be represented by a dot('.'). So, the regular expression below will match any string with 'gi' followed by any single character, ending with 'a':

.*gi.a.*

To match a literal dot, escape it using a slash:

\.

Implementing the Comparator

Using regular expressions, we can now implement a Java comparator that behaves like the SQL 'LIKE' operator:

import java.util.Comparator;
import java.util.regex.Pattern;

public class LikeComparator implements Comparator<String> {

    @Override
    public int compare(String s1, String s2) {
        Pattern pattern = Pattern.compile(s2);
        return pattern.matcher(s1).matches() ? 0 : 1;
    }
}

Example Usage

To use the comparator, simply instantiate it and compare strings using the 'compare' method:

LikeComparator comparator = new LikeComparator();

System.out.println(comparator.compare("digital", "%ital%")); // true
System.out.println(comparator.compare("digital", "%gi?a%")); // true
System.out.println(comparator.compare("digital", "digi%")); // true
System.out.println(comparator.compare("digital", "%cam%")); // false
System.out.println(comparator.compare("digital", "tal%")); // false

The above is the detailed content of How Can I Implement a Java Comparator with SQL's `LIKE` Operator Functionality?. For more information, please follow other related articles on the PHP Chinese website!