Скачать или смотреть How to Select a Single Line of Text in JavaFX TextArea with Caret Position

Learn how to select a line of text in a JavaFX TextArea based on the caret position, just like in SQL Developer.
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This video is based on the question https://stackoverflow.com/q/65094090/ asked by the user 'Josh Pulda' ( https://stackoverflow.com/u/9487248/ ) and on the answer https://stackoverflow.com/a/65094433/ provided by the user 'James_D' ( https://stackoverflow.com/u/2189127/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Select a Single Line of Text in JavaFX TextArea with Caret Position

When working with multi-line text areas in JavaFX, such as for a query input or editor, there might be times when you want to perform actions on an entire line of text based on the cursor's position. If you're from the SQL Developer realm, you're likely familiar with the functionality where you can easily select the complete line of text where the caret is placed. In this guide, we will walk through an effective solution for achieving this in your JavaFX application.

The Problem

Imagine you're building an application with JavaFX that allows users to execute multiple lines of SQL queries. You've implemented a TextArea, but you find it tough for users to select the appropriate line of text as they navigate using keyboard shortcuts. Specifically, you want to replicate the behavior of SQL Developer’s Ctrl + Enter functionality, which selects all text on the line where the cursor is located.

The Solution

We can achieve this by using the caret position within the TextArea to determine the start and end of the line of text where the caret resides. Here's a breakdown of the solution:

Step 1: Get the Caret Position

First, you need to retrieve the current position of the caret. This position gives us the index of the text where the cursor is currently located.

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

Step 2: Identify the Line’s Boundaries

Next, we need to locate the previous newline character before the caret position and the next newline character after. This way, we can define the range that corresponds to the entire line.

Previous Newline: The latest occurrence of the newline character (\n) before the caret position.

Next Newline: The first occurrence of the newline character after the caret position.

Step 3: Handle Edge Cases

It’s essential to consider edge cases, such as when the caret is placed at the end of the text area, where there may not be a next newline character. In such cases, we’ll use the length of the text as the endpoint.

Step 4: Select the Line

Finally, using the indices obtained from previous steps, we can select the relevant portion of the text:

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

Full Code Integration

To streamline everything, integrate the above logic into your event handling method. It will look something like this:

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

Conclusion

By implementing this approach, you can enhance the user experience in your JavaFX application by allowing users to swiftly select an entire line of text in a TextArea with a simple keyboard shortcut. This mimics the behavior found in SQL Developer, showcasing how small improvements can significantly impact user efficiency. Try this solution in your application, and watch how it elevates user interactions!