{"id":77727,"date":"2020-09-18T12:33:12","date_gmt":"2020-09-18T12:33:12","guid":{"rendered":"https:\/\/www.baeldung.com\/?p=87256"},"modified":"2020-09-18T12:33:12","modified_gmt":"2020-09-18T12:33:12","slug":"how-to-remove-a-prefix-from-strings-in-groovy","status":"publish","type":"post","link":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/2020\/09\/18\/how-to-remove-a-prefix-from-strings-in-groovy\/","title":{"rendered":"How to Remove a Prefix From Strings in Groovy"},"content":{"rendered":"

<\/p>\n

1. Introduction<\/h2>\n
<\/div>\n

In this quick tutorial, we’ll learn how to remove the prefix from a string in Groovy<\/a>.<\/p>\n

First, we’ll look at what the String<\/em> class offers for this purpose. After that, we’ll move on to regular expressions and see how we can use them to remove a prefix.<\/p>\n

2. Using String<\/em> Methods<\/h2>\n
<\/div>\n

Generally, Groovy<\/a> is considered a dynamic language for the Java ecosystem. Therefore, we can still use every Java String<\/em> class method along with new Groovy ones. However, for the removal of the prefix, there is still an absence of a straightforward method like removePrefix()<\/em>.<\/p>\n

Removing of a prefix from Groovy strings consists of two steps: first confirmation and then removal<\/strong>. Both of these steps can be performed using the StringGroovyMethods<\/em> class that offers many utility methods for string manipulations.<\/p>\n

2.1. startsWith()<\/em> Method<\/h3>\n
<\/div>\n

The startWith()<\/em> method tests if a string starts with a specific prefix. It returns true<\/em> if the prefix exists and false<\/em> otherwise.<\/p>\n

Let’s start with a groovy closure<\/a>:<\/p>\n

@Test \r\npublic void whenCasePrefixIsRemoved_thenReturnTrue(){\r\n    def trimPrefix = {\r\n        it.startsWith('Groovy-') ? it.minus('Groovy-') : it \r\n    }\r\n    def actual = trimPrefix(\"Groovy-Tutorials at Baeldung\")\r\n    def expected = \"Tutorials at Baeldung\"\r\n    assertEquals(expected, actual)\r\n}\r\n<\/code><\/pre>\n
Once existence is confirmed, then we can also use the substring()<\/em> method to remove it:<\/p>\n
trimPrefix.substring('Groovy-'.length())\r\n<\/code><\/pre>\n
2.2. startsWithIgnoreCase()<\/em>\u00a0Method<\/h3>\n
<\/div>\n
The startsWith()<\/em> method is case-sensitive<\/strong>. So, a manual effort is required to negate the effect of the case either by applying the toLowerCase()<\/em> or toUpperCase() <\/em>methods.<\/p>\n
As the name suggests, the startsWithIgnoreCase() <\/em>searches a prefix without case consideration. It returns true if a prefix exists and false otherwise.<\/p>\n
Let’s look at how to use this method:<\/p>\n
@Test\r\npublic void whenPrefixIsRemovedWithIgnoreCase_thenReturnTrue() {\r\n    String prefix = \"groovy-\"\r\n    String trimPrefix = \"Groovy-Tutorials at Baeldung\"\r\n    def actual\r\n    if(trimPrefix.startsWithIgnoreCase(prefix)) {\r\n        actual = trimPrefix.substring(prefix.length())\r\n    }\r\n    def expected = \"Tutorials at Baeldung\"\r\n    assertEquals(expected, actual)\r\n}\r\n<\/code><\/pre>\n
2.3. startsWithAny()<\/em>\u00a0Method<\/h3>\n
<\/div>\n
The above solutions are useful when we have to check only one prefix. When it comes to checking multiple prefixes, Groovy also provides support to check multiple prefixes.<\/p>\n
The startsWithAny()<\/em> method checks if the CharSequence<\/em> starts with any specified prefixes. <\/strong>Once the prefix is confirmed, we can apply logic according to requirements:<\/p>\n
String trimPrefix = \"Groovy-Tutorials at Baeldung\"\r\nif (trimPrefix.startsWithAny(\"Java\", \"Groovy\", \"Linux\")) {\r\n    \/\/ logic to remove prefix\r\n}\r\n<\/code><\/pre>\n
3. Using Regex<\/h2>\n
<\/div>\n
A regular expression is a powerful way to match or replace a pattern. Groovy has a pattern operator ~<\/a> that provides a simple way to create a java.util.regex.Pattern <\/em>instance.<\/p>\n
Let’s define a simple regular expression to remove a prefix:<\/p>\n
@Test\r\npublic void whenPrefixIsRemovedUsingRegex_thenReturnTrue() {\r\n    def regex = ~\"^groovy-\"\r\n    String trimPrefix = \"groovy-Tutorials at Baeldung\"\r\n    String actual = trimPrefix - regex\r\n    def expected = \"Tutorials at Baeldung\"\r\n    assertEquals(\"Tutorials at Baeldung\", actual)\r\n}\r\n<\/code><\/pre>\n
The case-insensitive version of the above regular expression:<\/p>\n
def regex = ~\"^([Gg])roovy-\"\r\n<\/code><\/pre>\n
The caret operator ^ will make sure that the specified substring exists at the start.<\/p>\n
3.1. replaceFirst()<\/em> Method<\/h3>\n
<\/div>\n
Using regular expressions along with native strings methods, we can perform very powerful tricks. The replaceFirst()<\/em> method is one of these methods. It replaces the first occurrence that matches the given regular expression.<\/p>\n
Let’s remove a prefix using the replaceFirst()<\/em> method:<\/p>\n
@Test\r\npublic void whenPrefixIsRemovedUsingReplaceFirst_thenReturnTrue() {\r\n    def regex = ~\"^groovy\"\r\n    String trimPrefix = \"groovyTutorials at Baeldung's groovy page\"\r\n    String actual = trimPrefix.replaceFirst(regex, \"\")\r\n    def expected = \"Tutorials at Baeldung's groovy page\"\r\n    assertEquals(expected, actual)\r\n}\r\n<\/code><\/pre>\n
3.2. replaceAll()<\/em> Method<\/h3>\n
<\/div>\n
Just like replaceFirst()<\/em>, the replaceAll() <\/em>also accepts a regular expression and given replacement. It replaces each substring that matches the given criteria<\/strong>. To remove a prefix, we can use this method too.<\/p>\n
Let’s use replaceAll()<\/em> to replace a substring at the start of the string only:<\/p>\n
@Test\r\npublic void whenPrefixIsRemovedUsingReplaceAll_thenReturnTrue() {\r\n    String trimPrefix = \"groovyTutorials at Baeldung groovy\"\r\n    String actual = trimPrefix.replaceAll(\/^groovy\/, \"\")\r\n    def expected = \"Tutorials at Baeldung groovy\"\r\n    assertEquals(expected, actual)\r\n}\r\n<\/code><\/pre>\n
4. Conclusion<\/h2>\n
<\/div>\n
In this quick tutorial, we explored several ways to remove prefixes from a string. To confirm the existence of a prefix, we saw how to do this for both uppercase and lowercase strings.<\/p>\n
At the same time, we’ve seen how to detect a prefix among many provided substrings. We also looked at multiple methods that can be used to remove a substring. Lastly, we briefly discussed the role of regex for this purpose.<\/p>\n
As always, all the code examples can be found over on GitHub<\/a>.<\/p>\n
The post How to Remove a Prefix From Strings in Groovy<\/a> first appeared on Baeldung<\/a>.<\/p>\n
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<\/p>","protected":false},"excerpt":{"rendered":"
Learn how to remove the prefix from a string using Groovy.<\/p>\n
The post How to Remove a Prefix From Strings in Groovy<\/a> first appeared on Baeldung<\/a>.<\/p>\n
<\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/a> <\/div>\n<\/div>","protected":false},"author":214,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"How to Remove a Prefix From Strings in Groovy - ITTeacherITFreelance.hk","description":"Learn how to remove the prefix from a string using Groovy. The post How to Remove a Prefix From Strings in Groovy first appeared on Baeldung .     &nb"},"footnotes":""},"categories":[6],"tags":[5337],"_links":{"self":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/77727"}],"collection":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/users\/214"}],"replies":[{"embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/comments?post=77727"}],"version-history":[{"count":7,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/77727\/revisions"}],"predecessor-version":[{"id":81484,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/posts\/77727\/revisions\/81484"}],"wp:attachment":[{"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/media?parent=77727"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/categories?post=77727"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itteacheritfreelance.hk\/wordpress\/index.php\/wp-json\/wp\/v2\/tags?post=77727"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}