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Java String Exercises: Replace each substring of a given string that matches the given regular expression with the given replacement

Java String: Exercise-25 with Solution

Write a Java program to replace each substring of a given string that matches the given regular expression with the given replacement.

Sample string: "The quick brown fox jumps over the lazy dog."

In the above string replace all the fox with cat.

Pictorial Presentation:

Java String Exercises: Replace each substring of a given string that matches the given regular expression with the given replacement

Sample Solution:

Java Code:

public class Exercise25 {
    
   public static void main(String[] args)
    {
        String str = "The quick brown fox jumps over the lazy dog.";

         // Replace all the 'dog' with 'cat'.
        String new_str = str.replaceAll("fox", "cat");
       
         // Display the strings for comparison.
        System.out.println("Original string: " + str);
        System.out.println("New String: " + new_str);
    }
}

Sample Output:

Original string: The quick brown fox jumps over the lazy dog.                                                 
New String: The quick brown cat jumps over the lazy dog.         

Flowchart:

Flowchart: Java String  Exercises - Replace each substring of a given string that matches the given regular expression with the given replacement

Visualize Java code execution (Python Tutor):


Java Code Editor:

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Previous: Write a Java program to replace a specified character with another character.
Next: Write a Java program to check whether a given string starts with the contents of another string.

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Java: Tips of the Day

Array vs ArrayLists:

The main difference between these two is that an Array is of fixed size so once you have created an Array you cannot change it but the ArrayList is not of fixed size. You can create instances of ArrayLists without specifying its size. So if you create such instances of an ArrayList without specifying its size Java will create an instance of an ArrayList of default size.

Once an ArrayList is full it re-sizes itself. In fact, an ArrayList is internally supported by an array. So when an ArrayList is resized it will slow down its performance a bit as the contents of the old Array must be copied to a new Array.

At the same time, it's compulsory to specify the size of an Array directly or indirectly while creating it. And also Arrays can store both primitives and objects while ArrayLists only can store objects.

Ref: https://bit.ly/3o8L2KH