{"id":126625,"date":"2024-11-27T18:00:50","date_gmt":"2024-11-27T12:30:50","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=126625"},"modified":"2024-11-27T18:11:06","modified_gmt":"2024-11-27T12:41:06","slug":"java-string-replace-method","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/java-string-replace-method\/","title":{"rendered":"Java String replace() Method with Examples"},"content":{"rendered":"

Strings in Java are objects backed internally by a char array. They are immutable, just like arrays; their values cannot be changed once initialized. This immutability makes them a fundamental data structure in Java, particularly for storing and manipulating text-based information.<\/p>\n

The String class in Java contains several useful methods for manipulating strings. One such method is the replace() method, which can be used to replace characters or substrings in a string with new characters or substrings. This makes it an indispensable tool for text processing and manipulation in Java.<\/p>\n

In this article, we’ll explore the intricacies of the Java String replace() method and how it can be leveraged to streamline string manipulation tasks.<\/p>\n

Java String replace() Method<\/h2>\n

The replace() method in the Java String class replaces every occurrence of a character\/substring with a new character\/substring and returns the resulting string.<\/p>\n

Syntax<\/strong><\/p>\n

The syntaxes for the two variants of replace() method are:<\/strong><\/p>\n

public String replace(char oldChar, char newChar)\r\n\r\npublic String replace(CharSequence target, CharSequence replacement)<\/pre>\n
Parameters<\/strong><\/p>\n
The parameters for replace() method are:<\/strong><\/p>\n
    \n
  • oldChar –<\/strong> The old char to be replaced<\/li>\n
  • newChar –<\/strong> The new char to replace oldChar<\/li>\n
  • target –<\/strong> The target substring to be replaced<\/li>\n
  • replacement –<\/strong> The replacement substring<\/li>\n<\/ul>\n
    Return Value<\/strong><\/p>\n
    The replace() method returns a string resulting from replacing all occurrences of oldChar\/target with newChar\/replacement, respectively.<\/p>\n
    Examples of Java String replace()<\/h3>\n
    Let’s look at some examples to understand the usage of replace() method.<\/p>\n
    Example 1:<\/strong> Using replace(char old, char new)<\/p>\n
    public class StringReplaceExample {\r\n    public static void main(String[] args) {\r\n        String str = \"Hello World\";\r\n        String newStr = str.replace('l', 'w');\r\n        System.out.println(newStr);\r\n    }\r\n}<\/pre>\n
    Output:<\/strong>
    \nHewwo Word<\/p>\n
    Example 2:<\/strong> Using replace(String target, String replacement)<\/p>\n
    public class StringReplaceExample {\r\n    public static void main(String[] args) {\r\n        String str = \"Hello World\";\r\n        String newStr = str.replace(\"World\", \"Universe\");\r\n        System.out.println(newStr);\r\n    }\r\n}<\/pre>\n
    Output:<\/strong>
    \nHello Universe<\/p>\n
    Exceptions with replace() Method<\/h3>\n
    If we pass a null regular expression to replace(), it results in NullPointerException.<\/p>\n
    For example:<\/strong><\/p>\n
    public class StringReplaceExample {\r\n    public static void main(String[] args) {\r\n        String str = \"Hello\";\r\n        String regex = null;\r\n\r\n        try {\r\n            str = str.replace(regex, \"Hi\");\r\n            System.out.println(str);\r\n        } catch (NullPointerException e) {\r\n            System.out.println(\"NullPointerException occurred: \" + e.getMessage());\r\n        }\r\n    }\r\n}<\/pre>\n
    Output:<\/strong>
    \nNullPointerException occurred:<\/strong> replace(CharSequence target, CharSequence replacement)<\/p>\n
    This is because replace() expects a valid regular expression and cannot work with a null value.<\/p>\n
    Java String replaceFirst()<\/h3>\n
    Along with replace(), String class also provides replaceFirst() method which replaces only the first occurrence of a substring.<\/p>\n
    Syntax<\/strong><\/p>\n
    public String replaceFirst(String regex, String replacement)<\/pre>\n
    Parameters<\/strong><\/p>\n
    regex – The regular expression to match
    \nreplacement – The string to replace the regex<\/p>\n
    Return Value<\/strong><\/p>\n
    It returns a string with the first matching regex replaced.<\/p>\n
    Example of Java String replaceFirst()<\/h3>\n
    public class StringReplaceExample {\r\n    public static void main(String[] args) {\r\n        String str = \"Hello World\";\r\n        String result = str.replaceFirst(\"l\", \"w\");\r\n        System.out.println(result);\r\n    }\r\n}<\/pre>\n
    Output:<\/strong>
    \nHewlo World<\/p>\n
    Conclusion<\/h3>\n
    In conclusion, the Java String replace() method is valuable for manipulating strings. It allows you to replace all occurrences of a character or substring with a new character or substring in a string. There are two variants of the method, one for replacing characters and another for replacing substrings. It returns a new string with the replacements, leaving the original string unchanged. However, it’s important to note that passing a null regular expression to replace() will result in a NullPointerException.<\/p>\n
    Additionally, Java offers a replaceFirst() method to replace only the first occurrence of a substring in a string, providing flexibility in string manipulation.<\/p>\n","protected":false},"excerpt":{"rendered":"
    Strings in Java are objects backed internally by a char array. They are immutable, just like arrays; their values cannot be changed once initialized. This immutability makes them a fundamental data structure in Java,...<\/p>\n","protected":false},"author":86671,"featured_media":134334,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[7345,31229,31224,31227,31078,8152,31230,31228,31226,31225],"class_list":["post-126625","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java","tag-java","tag-java-replace-method","tag-java-string-replace-method","tag-java-string-replace-method-with-examples","tag-java-tutorials","tag-learn-java","tag-replace-method","tag-replace-method-in-java","tag-string-replace-method","tag-string-replace-method-in-java"],"yoast_head":"\nJava String replace() Method with Examples - DataFlair<\/title>\n<meta name=\"description\" content=\"Java String replace() method allows you to replace all occurrences of a character or substring with a new character or substring in a string.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/data-flair.training\/blogs\/java-string-replace-method\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Java String replace() Method with Examples - 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