Replace() in Java - How to replace a character in a string

June 13, 2018 Vertex Academy how to replace a character in a string java, how to replace a substring in java, java replace, java replace example, replace method in java

replace() in Java

This method replaces a character (or substring) in a string.

Syntax:

public String replace(char oldChar, char newChar);

1	public String replace(char oldChar, char newChar);

public String replace(String s1, String s2);

1	public String replace(String s1, String s2);

How to Call the Method:

String newString =  oldString.replace(char oldChar, char newChar);

1	String newString = oldString.replace(char oldChar, char newChar);

String newString =  oldString.replace(String sub1, String sub2);

1	String newString = oldString.replace(String sub1, String sub2);

Example:

public class Test {
    public static void main(String[] args) {
 
        String oldString = "ABC";
        String newString =  oldString.replace('A', 'B');
 
        System.out.println("Old string: " + oldString);
        System.out.println("New string: " + newString);
    }
}

public class Test {

public static void main(String[] args) {

String oldString = "ABC";

String newString = oldString.replace('A', 'B');

System.out.println("Old string: " + oldString);

System.out.println("New string: " + newString);

}

If you run this code on your computer, you will see the following in the console:

Commentary:

Initially, there is a variable called oldString with the text "ABC". To replace 'A' with 'B', we used the replace() method.

As the first parameter, we set what we would like to replace. In this case it is the character 'A'
As the second parameter, we set what we would like to replace it with. In this case with the character 'B'

As a result, we've got a new string with the text "BBC".

Please note, that the first string (oldString) wasn't changed when we used the replace() method. That means that the replace() method returned a new string.

That's all. You can find more articles in our Java Tutorial for Beginners.