Скачать или смотреть How to Properly Insert Data into an Array in Java

A comprehensive guide on how to fix `NullPointerExceptions` when inserting data into arrays in Java, ideal for beginners.
---
This video is based on the question https://stackoverflow.com/q/62790247/ asked by the user 'Peter Gigih' ( https://stackoverflow.com/u/9887451/ ) and on the answer https://stackoverflow.com/a/62790677/ provided by the user 'fatma zehra güç' ( https://stackoverflow.com/u/13399024/ ) 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: How to Insert Data To Array

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.
---
Understanding How to Insert Data into an Array in Java

If you're just starting with Java and arrays, you may encounter a common problem: trying to insert data into an array that hasn't been properly initialized. This can often lead to frustrating errors, like the dreaded NullPointerException. In this guide, we'll break down this problem and provide a clear solution to ensure you're able to insert data into an array with ease.

The Problem: NullPointerException

Take a look at the following code snippet that someone attempted to run:

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

In this example, we see a NullPointerException because the normalisasiT1 array is initialized as null. Since you are trying to access an index of a null reference when doing normalisasiT1[i], the program crashes.

The Solution: Initializing the Array

To fix the NullPointerException, you need to ensure that the array is properly initialized before you try to insert any data into it. Here’s how you can do that:

Step 1: Determine the Size of the Array

Before you initialize your array, you should know how many elements it will store. In your case, the size might be determined by the number of rows in jTable1.

Step 2: Initialize the Array

Once you have determined the size, you can initialize your array like so:

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

Step 3: Insert Data into the Array

Now that you've initialized the array, you can safely populate it without encountering a NullPointerException. Here’s the revised loop:

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

Summary

To summarize, if you encounter a NullPointerException while trying to insert data into an array in Java:

Initialize your array by defining its size based on your application's needs.

Insert your data only after ensuring that the array is initialized.

By following these steps, you will be able to avoid common pitfalls and effectively manage arrays in your Java applications. Happy coding!