A binary search tree (BST) is a binary tree data structure where each node has at most two children, and the left subtree contains nodes with values less than the parent node, while the right subtree contains nodes with values greater than the parent node. Implementing a binary search tree in Java involves creating classes for the tree structure and defining methods to perform operations like insertion, deletion, and traversal. Here's a step-by-step guide to implement a basic binary search tree in Java:

1. Define a Node class:
   Create a `Node` class to represent the nodes in the BST. Each node should contain data, a reference to the left child, and a reference to the right child.

```java
class Node {
    int data;
    Node left;
    Node right;

    public Node(int data) {
        this.data = data;
        this.left = null;
        this.right = null;
    }
}
```

2. Create a BinarySearchTree class:
   Next, create a `BinarySearchTree` class to manage the binary search tree. This class will include methods to insert, search, delete, and traverse elements in the tree.

```java
public class BinarySearchTree {
    private Node root;

    public BinarySearchTree() {
        root = null;
    }

    // Method to insert a value into the BST
    public void insert(int data) {
        root = insertRecursive(root, data);
    }

    private Node insertRecursive(Node current, int data) {
        if (current == null) {
            return new Node(data);
        }

        if (data < current.data) {
            current.left = insertRecursive(current.left, data);
        } else if (data > current.data) {
            current.right = insertRecursive(current.right, data);
        }

        return current;
    }

    // Method to search for a value in the BST
    public boolean search(int data) {
        return searchRecursive(root, data);
    }

    private boolean searchRecursive(Node current, int data) {
        if (current == null) {
            return false;
        }

        if (data == current.data) {
            return true;
        }

        if (data < current.data) {
            return searchRecursive(current.left, data);
        } else {
            return searchRecursive(current.right, data);
        }
    }

    // Method to perform an in-order traversal of the BST
    public void inOrderTraversal() {
        inOrderRecursive(root);
    }

    private void inOrderRecursive(Node node) {
        if (node != null) {
            inOrderRecursive(node.left);
            System.out.print(node.data + " ");
            inOrderRecursive(node.right);
        }
    }
}
```

3. Test the BinarySearchTree:
   You can create an instance of the `BinarySearchTree` class and use it to insert, search, and traverse elements in the BST.

```java
public class Main {
    public static void main(String[] args) {
        BinarySearchTree bst = new BinarySearchTree();

        bst.insert(50);
        bst.insert(30);
        bst.insert(70);
        bst.insert(20);
        bst.insert(40);
        bst.insert(60);
        bst.insert(80);

        System.out.println("In-order traversal:");
        bst.inOrderTraversal(); // Output: 20 30 40 50 60 70 80

        int searchValue = 40;
        boolean found = bst.search(searchValue);
        System.out.println("\nSearch for " + searchValue + ": " + found); // Output: true
    }
}
```

This example demonstrates the basic implementation of a binary search tree in Java, including insertion, searching, and in-order traversal operations. You can extend this implementation by adding methods for deletion, pre-order and post-order traversals, and other operations as needed for your specific use case.