Write a Java program which accepts distance in kilo meters as input and displays its Miles equivalent, or vice versa, as per the choice of user.

Below is the Java program that accepts distance in kilometers as input and displays its miles equivalent, or vice versa, as per the choice of the user:

import java.util.Scanner;

public class DistanceConverter {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Prompt user for choice
        System.out.println("Enter 1 to convert kilometers to miles");
        System.out.println("Enter 2 to convert miles to kilometers");
        int choice = scanner.nextInt();

        // Check user's choice
        if(choice == 1) {
            // Convert kilometers to miles
            System.out.println("Enter distance in kilometers: ");
            double kilometers = scanner.nextDouble();
            double miles = kilometers * 0.621371; // 1 kilometer = 0.621371 miles
            System.out.println(kilometers + " kilometers is equal to " + miles + " miles.");
        } else if(choice == 2) {
            // Convert miles to kilometers
            System.out.println("Enter distance in miles: ");
            double miles = scanner.nextDouble();
            double kilometers = miles / 0.621371; // 1 mile = 0.621371 kilometers
            System.out.println(miles + " miles is equal to " + kilometers + " kilometers.");
        } else {
            System.out.println("Invalid choice! Please enter 1 or 2.");
        }

        scanner.close();
    }
}

This program prompts the user to enter their choice – whether they want to convert kilometers to miles or miles to kilometers. Based on the user's choice, it then prompts the user to enter the distance value and performs the conversion accordingly. The conversion formulas are used to convert between kilometers and miles. Finally, the program displays the converted distance to the user.