The java string replaceAll() method returns a string replacing all the sequence of characters matching regex and replacement string.

Internal implementation

public String replaceAll(String regex, String replacement) {  
        return Pattern.compile(regex).matcher(this).replaceAll(replacement);  
}

Signature

public String replaceAll(String regex, String replacement)

Parameters

regex : regular expression

replacement : replacement sequence of characters

Returns

replaced string

Java String replaceAll() example: replace character

Let’s see an example to replace all the occurrences of a single character.

public class ReplaceAllExample1{  
public static void main(String args[]){  
String s1="javatpoint is a very good website";  
String replaceString=s1.replaceAll("a","e");//replaces all occurrences of "a" to "e"  
System.out.println(replaceString);  
}}
jevetpoint is e very good website

Java String replaceAll() example: replace word

Let’s see an example to replace all the occurrences of single word or set of words.

public class ReplaceAllExample2{  
public static void main(String args[]){  
String s1="My name is Khan. My name is Bob. My name is Sonoo.";  
String replaceString=s1.replaceAll("is","was");//replaces all occurrences of "is" to "was"  
System.out.println(replaceString);  
}}
My name was Khan. My name was Bob. My name was Sonoo.

Java String replaceAll() example: remove white spaces

Let’s see an example to remove all the occurrences of white spaces.

public class ReplaceAllExample3{  
public static void main(String args[]){  
String s1="My name is Khan. My name is Bob. My name is Sonoo.";  
String replaceString=s1.replaceAll("\\s","");  
System.out.println(replaceString);  
}}

MynameisKhan.MynameisBob.MynameisSonoo.