How can we replace specific characters in a Java string?

In Java, the method to replace specified characters in a string is by using the replace() method of the String class. This method takes two parameters, the first one being the character to replace, and the second one being the character to replace it with. For example:

String str = "Hello world!";
String newStr = str.replace('o', '@');
System.out.println(newStr);

The output result is:

Hell@ w@rld!

In the example above, we replaced the character ‘o’ with ‘@’ in the string.