Master Java String Manipulation with strman-java: 23 Essential Methods Explained

Many beginner programmers feel their code looks terrible, but using well‑tested open‑source libraries can dramatically improve code quality. The strman-java library (1.3k stars on GitHub) offers a concise, Java 8‑based API for common string operations.

01 append

Append variable string arguments to the end of a base string. Strman.append("沉", "默", "王", "二"); Result:

沉默王二

02 appendArray

Append an array of strings to the end of a base string.

String[] strs = {"默", "王", "二"};
Strman.appendArray("沉", strs);

Result:

沉默王二

03 at

Retrieve the character at a specified index, supporting negative indices and returning Optional.empty() when out of range.

Strman.at("沉默王二", 0);
Strman.at("沉默王二", -1);
Strman.at("沉默王二", 4);

Results: Optional[沉], Optional[二],

Optional.empty

04 between

Return an array of substrings located between a start and end delimiter.

String[] results = Strman.between("[沉默王二][一枚有趣的程序员]", "[", "]");
System.out.println(Arrays.toString(results));

Result:

[沉默王二, 一枚有趣的程序员]

05 chars

Split a string into an array of its individual characters.

String[] results = Strman.chars("沉默王二");
System.out.println(Arrays.toString(results));

Result:

[沉, 默, 王, 二]

06 charsCount

Count the occurrences of each character in a string.

Map<Character, Long> map = Strman.charsCount("沉默王二的妹妹叫沉默王三");
System.out.println(map);

Result:

{的=1, 默=2, 三=1, 妹=2, 沉=2, 叫=1, 王=2, 二=1}

07 collapseWhitespace

Replace multiple consecutive whitespace characters with a single space.

Strman.collapseWhitespace("沉默王二       一枚有趣的程序员");

Result:

沉默王二 一枚有趣的程序员

08 contains

Check whether a string contains a given substring, optionally case‑insensitive.

Strman.contains("沉默王二", "沉");
Strman.contains("Abbc", "a", false);

Both calls return true.

09 containsAny

Check whether a string contains any of the strings in an array.

Strman.containsAny("沉默王二", new String[]{"沉", "三"});
Strman.containsAny("沉默王二", new String[]{"沉默", "三"});
Strman.containsAny("沉默王二", new String[]{"不", "三"});

Results: true, true, false.

10 endsWith

Verify whether a string ends with a given suffix, with optional case‑sensitivity.

Strman.endsWith("沉默王二", "二");
Strman.endsWith("Abbc", "A", false);

Results: true, false.

11 ensureLeft

Ensure a string starts with a given prefix; if not, prepend it.

Strman.ensureLeft("沉默王二", "沉");
Strman.ensureLeft("默王二", "沉");

Both calls produce 沉默王二.

12 base64Encode

Encode a string to Base64 using Java 8's Base64 class. Strman.base64Encode("沉默王二"); Result: 5rKJ6buY546L5LqM.

13 binEncode

Convert a string to its 16‑bit Unicode binary representation. Strman.binEncode("沉默王二"); Result:

0110110010001001100111101101100001110011100010110100111010001100

14 first

Return the first n characters of a string as an Optional.

Strman.first("沉默王二", 0);
Strman.first("沉默王二", 1);
Strman.first("沉默王二", 2);

Results: Optional.empty, Optional[沉], Optional[沉默].

15 head

Return the first character of a string (a shortcut for first(value, 1)). Strman.head("沉默王二"); Result: Optional[沉].

16 unequal

Check whether two strings are not equal.

Strman.unequal("沉默王二", "沉默王三");

Result: true.

17 insert

Insert a substring at a specified index.

Strman.insert("沉默二", "王", 2);

Result: 沉默王二.

18 repeat

Repeat a string a given number of times.

Strman.repeat("沉默王二", 3);

Result: 沉默王二沉默王二沉默王二.

19 leftPad

Pad a string on the left to a desired total length.

Strman.leftPad("王二", "沉默", 6);

Result: 沉默沉默沉默沉默王二.

20 reverse

Reverse the characters of a string.

Strman.reverse("沉默王二");

Result: 二王默沉.

21 safeTruncate

Truncate a string to a maximum length without breaking words, appending a filler.

Strman.safeTruncate("Java is the best", 13, "...");

Result: Java is....

22 shuffle

Randomly shuffle the characters of a string.

Strman.shuffle("沉默王二");

Result (example): 王默二沉.

The library also provides many other useful utilities such as surround, rightPad, removeEmptyStrings, and more; see the official documentation for the full list.

https://github.com/shekhargulati/strman-java/wiki