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Java program to replace a substring with another substring into the string at all places using regular expression

Java example to replace a substring with another substring into the string at all places using regular expression.
Submitted by Nidhi, on June 13, 2022

Problem statement

In this program, we will create a string and a regular expression pattern. Here we will replace a substring pattern with another substring using the replaceAll() method.

Source Code

The source code to replace a substring with another substring into string at all places using regular expression is given below. The given program is compiled and executed successfully.

// Java program to replace a substring with another substring 
// into the string at all places using regular expression

import java.util.regex.*;

public class Main {
  public static void main(String[] args) {
    String str = "abc pqr abc lmn xyz";
    String regex = "abc";
    String replace = "123";

    Pattern pattern = Pattern.compile(regex);
    Matcher matcher = pattern.matcher(str);

    str = matcher.replaceAll(replace);
    System.out.println(str);
  }
}

Output

123 pqr 123 lmn xyz

Explanation

In the above program, we imported the "java.util.regex.*" package to use the Pattern and Matcher classes. Here, we created a public class Main.

The Main class contains a main() method. The main() method is the entry point for the program. And, created a string and pattern. Then we used the replaceAll() method to replace a substring pattern "abc" with another substring "123", and printed the updated string.