String replace()

The replace() method in java is a part of the String class and is used to create a new string by replacing occurrences of a specified character or substring with another character or substring. The method returns a new string with the replacements made.

The basic syntax of the replace() method is as follows:

String replace(char oldChar, char newChar)
String replace(CharSequence target, CharSequence replacement)

Here’s how you can use it:

1. Replacing a character:

String original = "Hello, world!";
String replaced = original.replace('o', '0'); // "Hell0, w0rld!"

In this example, the replace('o', '0') call replaces all occurrences of the character ‘o’ with the character ‘0’, resulting in the string “Hell0, w0rld!”.

2. Replacing a substring:

String original = "Hello, world!";
String replaced = original.replace("world", "Java"); // "Hello, Java!"

In this example, the replace("world", "Java") call replaces the substring “world” with the substring “Java”, resulting in the string “Hello, Java!”.

Keep in mind:

• The replace() method creates a new string with the replacements made. The original string remains unchanged.
• The replacements are case-sensitive. If you need to perform case-insensitive replacements, you’ll need to use additional logic or regular expressions.
• For both replace() methods, you can replace occurrences of characters or substrings.
• The first replace() method replaces individual characters, while the second method replaces entire substrings.

Here are a few more examples:

String text = "aabbcc";
String replaced1 = text.replace('a', 'x'); // "xxbbcc"
String replaced2 = text.replace("bb", "yy"); // "aayycc"

In these examples, replaced1 replaces occurrences of ‘a’ with ‘x’, resulting in “xxbbcc”. replaced2 replaces occurrences of “bb” with “yy”, resulting in “aayycc”.