Скачать или смотреть How to Replace a Character in a String with Java

Learn how to efficiently replace all instances of a character in a string using Java. This guide breaks down the approach step by step to ensure your code works correctly.
---
This video is based on the question https://stackoverflow.com/q/62701365/ asked by the user 'Gustavo C' ( https://stackoverflow.com/u/13826781/ ) and on the answer https://stackoverflow.com/a/62701460/ provided by the user 'Naetmul' ( https://stackoverflow.com/u/869330/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Replace a certain character from a String

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Replace a Character in a String with Java

When you're working with strings in Java, a common task is replacing characters within those strings. Whether it's to correct a typo, transform a string, or customize user inputs, knowing how to efficiently replace characters is essential for any programmer.

In this guide, we'll address a typical problem: a user wants to replace a character in a string but finds that their program is only replacing the first occurrence and not every single instance, as intended.

Understanding the Problem

Imagine you have a simple program where a user can input a word and specify a character they want to replace along with the replacement character. Here's the breakdown of the requirement:

The user inputs a word, e.g., "hello".

The user specifies the character to replace, e.g., "l".

The user specifies the replacement character, e.g., "x".

The expected output should replace all instances of "l" in "hello" resulting in "hexxo".

However, many might find the code they wrote only replaces the first "l", which is not the desired outcome.

Analyzing Your Code

Let's take a look at the problematic code:

[[See Video to Reveal this Text or Code Snippet]]

Issues Identified

Repeated Updates to newWord: The code updates newWord every time it finds a match for letterToReplace. However, these updates do not consider the already modified parts of the word, causing it to only replace the first occurrence each time.

Improper Usage of substring(): Inside the loop, the code is using indexOf(letterToReplace) which always returns the first index of the character, instead of the current index i from the loop. This leads to incorrect string slicing.

The Solution

Here’s how you can fix the issue to ensure that all instances of a character are replaced:

Use a StringBuilder: Instead of modifying the string by creating slices, use a StringBuilder to efficiently build the new string.

Iterate through the characters: Check each character in the original string and append the appropriate character to StringBuilder.

Corrected Code Example

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By implementing the above suggestions, your program should now successfully replace all occurrences of the specified character, ensuring users get the result they expect. This approach not only solves the initial problem efficiently but also helps in improving your understanding of string manipulation in Java.

Feel free to experiment with the code and test various strings and characters to fully grasp how it works. Happy coding!