Allow Java to recognize input not equal to a wanted value

Allow Java to recognize input not equal to a wanted value

I am new to both Java and this site so please have mercy on any mistake I
may make, I am at my wits end!
I am trying to make a program that calculates the speed of sound through
different mediums. As of now the program will ask the user for input on
the distance and allow input, same for the medium. I created several cases
that will calculate the the answer of the given medium which work
properly.
The issue is when I try to create a loop that recognizes if the medium
input is not one of the 4 options available. I was able to successfully
create a loop that recognizes if the distance input is not a numeric value
and tried using similar principles for the medium input but either keep
getting stuck in infinite loops or getting the message I created for a
wrong entry when I entered the right option. I have tried the basic loops
that I have been taught: for, do-while, etc., but am stuck. Any and all
suggestions are appreciated, thank you so much!
public static void main(String[] args) {
//prompt the user about the purpose of this program
System.out.println(" The purpose of this program is to calculate the
speed of sound through several mediums.\n The program user will input
a distance in feet followed by a mediums and the program will output
the speed in feet per second and miles per hour\n");
//declare variables
Scanner keyboard = new Scanner(System.in);
final double Air = 1126.1;
final double Water = 4603.2;
final double Steel = 20013.3;
final double Earth = 22967.4;
double OneFootPerSecond = .68181818182;
double Distance;
double AirSpeed;
double WaterSpeed;
double SteelSpeed;
double EarthSpeed;
System.out.print(" What is the distance in feet:" );
//ask the user to input variables
while (!keyboard.hasNextDouble()){
System.out.println("Please enter a valid numeric value, try again:
");
keyboard.next();
}
Distance =keyboard.nextDouble();
{
System.out.print("Input the media: Air, Water, Steel, or Earth: ");
String Input = keyboard.next();
Input.toLowerCase();
switch (Input)
{
case "air":
AirSpeed = Distance/Air;
System.out.print("\n \nThe time to for sound to travel ");
System.out.print(Distance);
System.out.print(" feet through AIR" +"\n");
System.out.printf("%.6f", AirSpeed);
System.out.print(" seconds or ");
System.out.printf("%.1f", OneFootPerSecond*Air);
System.out.print(" miles per hour.");
System.out.print("\n \nEnter Yes for another calculation, else
No: ");
String Another = keyboard.next();
Another.toLowerCase();
break;
case "water":
WaterSpeed = Distance/Water;
System.out.print("\nThe time to for sound to travel ");
System.out.print(Distance);
System.out.print(" feet through WATER" +"\n");
System.out.printf("%.6f",WaterSpeed);
System.out.print(" seconds or ");
System.out.printf("%.1f", OneFootPerSecond*Water);
System.out.print(" miles per hour.");
break;
case "steel":
SteelSpeed = Distance/Steel;
System.out.print("\nThe time to for sound to travel ");
System.out.print(Distance);
System.out.print(" feet through STEEL" +"\n");
System.out.printf("%.6f",SteelSpeed);
System.out.print(" seconds or ");
System.out.printf("%.1f", OneFootPerSecond*Steel);
System.out.print(" miles per hour.");
break;
case "earth":
EarthSpeed = Distance/Water;
System.out.print("\nThe time to for sound to travel ");
System.out.print(Distance);
System.out.print(" feet through EARTH" +"\n");
System.out.printf("%.6f",EarthSpeed);
System.out.print(" seconds or ");
System.out.printf("%.1f", OneFootPerSecond*Earth);
System.out.print(" miles per hour.");
break;