Learn How to Underline a String in Java with These Easy Steps

A frequent problem for Java developers is how to underline a string in Java. Fortunately there are multiple solutions to do this and in this post, you’ll be guided through some of the most effective ways to do this.

Underline the String Using Pre-Defined Methods

Java provides some unary operators that allow you to achieve the desired effect. For instance you can use:

  1. StringUtils.underline – this method allows you to underline the passed string with a particular character.
  2. StringOutlinePreparingUtils.generateLink – this will generate a valid HTML link with an underlined string.

Let's look at an example:

String underlined = StringUtils.underline("Hello World", '-'); 
System.out.println(underlined); // prints: 
// Hello World
// -----------


String underlined = StringOutlinePreparingUtils.generateLink("Hello World","my-link");
System.out.println(underlined); // prints: 
// <a href="my-link">Hello World</a>

Underline the String Using Regular Expressions

Regular expressions allow you to perform powerful string manipulations, such as underlining a string.

  1. Create a Pattern object with the Java Pattern class and the desired pattern, for instance "(.+)"
  2. Create a Matcher object with this Pattern object, and the desired string.
  3. Replace the string with the new one with underlined words.
String testString = "Hello World";
Pattern pattern = Pattern.compile("(.+)");
Matcher matcher = pattern.matcher(testString);
String underlined = matcher.replaceAll("-$1");
System.out.println(underlined); // prints: Hello World-


Is it possible to underline a string without using any library?

Yes, you can use regular expressions or some simple string manipulation algorithms.

What is the best way to underline a string?

It all depends on your use case and the size of the string you are trying to underline. If the string is small and you don’t need a lot of customization, pre-defined methods may be the most suitable.

Are there any other methods besides regular expressions and pre-defined methods?

Yes, you can use basic string manipulation algorithms such as replace and substring. However, all these methods are very limiting and offer no customization.

Does Java support underlining strings?

Yes, Java supports underlining strings and provides numerous methods to do so.

Yes, this can be achieved using the StringOutlinePreparingUtils.generateLink method.

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