String Functions in CLIPS

The standard library’s String class provides many useful string-related functions. Here are some examples to give you a sense of the class and its methods.

import java.util.Arrays;

public class StringFunctions {
    // We create a shorthand for System.out.println as we'll use it a lot below.
    private static void p(String s) {
        System.out.println(s);
    }

    public static void main(String[] args) {
        // Here's a sample of the methods available in String.
        // Since these are methods on the String object itself,
        // we call them directly on the string in question.
        // You can find more methods in the String class documentation.

        p("Contains:  " + "test".contains("es"));
        p("Count:     " + countOccurrences("test", 't'));
        p("StartsWith: " + "test".startsWith("te"));
        p("EndsWith: " + "test".endsWith("st"));
        p("IndexOf:   " + "test".indexOf("e"));
        p("Join:      " + String.join("-", "a", "b"));
        p("Repeat:    " + "a".repeat(5));
        p("Replace:   " + "foo".replace("o", "0"));
        p("Replace:   " + "foo".replaceFirst("o", "0"));
        p("Split:     " + Arrays.toString("a-b-c-d-e".split("-")));
        p("ToLower:   " + "TEST".toLowerCase());
        p("ToUpper:   " + "test".toUpperCase());
    }

    // Java doesn't have a built-in count method, so we implement our own
    private static int countOccurrences(String str, char ch) {
        return (int) str.chars().filter(c -> c == ch).count();
    }
}

When you run this program, you’ll get:

$ java StringFunctions
Contains:  true
Count:     2
StartsWith: true
EndsWith: true
IndexOf:   1
Join:      a-b
Repeat:    aaaaa
Replace:   f00
Replace:   f0o
Split:     [a, b, c, d, e]
ToLower:   test
ToUpper:   TEST

Note that Java’s String methods are slightly different from the functions in the Go strings package:

Most operations are methods on the String object rather than standalone functions.
Java doesn’t have a built-in Count method, so we implemented our own.
HasPrefix and HasSuffix are called startsWith and endsWith in Java.
Index is called indexOf in Java.
Join is a static method on the String class in Java.
Replace in Java replaces all occurrences by default, while replaceFirst replaces only the first occurrence.

These differences reflect the object-oriented nature of Java compared to Go’s more procedural approach to string manipulation.

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String Functions in CLIPS