Here is an octree system to use in Java. This system allows you to store object with the tree, and retreive them.

Step 1: Add my release repository.

<repositories>
    <repository>
        <id>Ryandw11</id>
        <url>https://repo.ryandw11.com/repository/maven-releases/</url>
    </repository>
</repositories>

Step 2: Add the dependency

<dependency>
    <groupId>me.ryandw11</groupId>
    <artifactId>Octree</artifactId>
    <version>1.0</version>
</dependency>

repositories {
    maven { url 'https://repo.ryandw11.com/repository/maven-releases/' }
}
dependencies {
    implementation 'me.ryandw11:Octree:1.0'
}

The octree is a generic class. You can tell it what value you want to store at each point.

Octree<String> octree = new Octree<>(0,0,0, 7, 7, 7);

The 0, 0, 0 is the 3d point. 7, 7, 7 is also a 3d point. Those two points are the bounds of the tree. You cannot have any points outside of the bounds.

octree.insert(4, 5, 4, "hello world!");

octree.find(4, 5, 4); // returns true

String s = octree.get(4, 5, 4);
// s than equals "hello world!"

octree.remove(4, 5, 4);
// Returns a boolean if it was successful or not.