Java String replaceAll()

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

Signature:

public Str replaceAll(String regex, String replacement)
Internal implementation

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

regex : regular expression

replacement : replacement sequence of characters

Returns

replaced string

Example

public class Test
{
    public static void main(String args[]) 
   {
        String s = "cprogramcoding is a site providing free tutorials";
        //remove white spaces
        String s2 = s.replaceAll("\\s", "");
        System.out.println(s2);
    }
}


Output:

cprogramcodingisasiteprovidingfreetutorials
Java String replaceAll() example: replace character

See an example to replace all the occurrences of a single character.


public class Test
{  
public static void main(String args[])
{  
String str1="cprogramcoding is a very good website";  
String re=str1.replaceAll("a","e");
System.out.println(re);  
}
}


Output:

cprogremcoding is e very good website
Java String replaceAll() example: replace word

See an example to replace all the occurrences of single word or set of words.


public class Test
{  
public static void main(String args[])
{  
String str1="My name is Rama.";  
String re=str1.replaceAll("is","was");
System.out.println(re);  
}
}


Output:

My name was Rama.
Another Java String replaceAll() example: remove white spaces

See an example to remove all the occurrences of white spaces.


public class Test
{  
public static void main(String args[])
{  
String str="My name is cprogramcoding.";  
String re=str.replaceAll("\\s","");  
System.out.println(re);  
}
}


Output:

Mynameiscprogramcoding.
Java - String replaceFirst() Method

The method replaces the first substring of the given string which matches that regular expression.

Syntax

public Str replaceFirst(String rgex, String replacement)
Parameters

rgex − the regular expression to which given string need to matched.

replacement − the string that replaces regular expression.

Return Value

This method returns resulting String as an output.


public class Test
{
    public static void main(String args[]) 
   {
        String str = "This website providing free tutorials";
        String str1 = str.replaceFirst("s", "9");
        System.out.println(str1);
    }
}


Output:

Thi9 website providing free tutorials



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