How to execute a block of code when a key is pressed?

Question

So basically Im trying to find a way to execute a block of code when I press down a key instead of having to scan in a string then pressing enter to invoke it. This is my first time asking a question here, also Im not really advance when it comes to code. Just trying to learn new things that will advance my coding knowledge. Here is my current code:

Main method (Im trying to change the part where I scan in the variable "key"):

import java.util.Scanner;

public class testGame {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    dungeon numberOne = new dungeon();

    String key;
    numberOne.setPlayer();
    numberOne.printLayout();

    Scanner input = new Scanner(System.in);
    for(int x = 0; x < Integer.MAX_VALUE; x++)
    {
        key = input.next();
        if(key.equals("w"))
        {
            numberOne.moveUp();
            numberOne.printLayout();

        }
        else if(key.equals("d"))
        {
            numberOne.moveRight();
            numberOne.printLayout();

        }
        else if(key.equals("s"))
        {
            numberOne.moveDown();
            numberOne.printLayout();

        }
        else if(key.equals("a"))
        {
            numberOne.moveLeft();
            numberOne.printLayout();

        }
        else
        {
            numberOne.printLayout();
        }
    }
}
}

Helper Class:

public class dungeon {
    private monster[] randMonster = new monster [10];
    private String printDungeon ="";
    private int x = 17;
    private int y = 34;
    private String pastLayout = "H";
    private String currentPostion = "O";
    private String[][] layout = //I deleted this as it was long. It was an 
 ASCII art layout..


public void printLayout()
    {
        for(int x = 0; x < layout.length; x ++)
        {
            for(int y = 0; y < layout[0].length; y++)
            {
                printDungeon = printDungeon + layout[x][y];
            }
            System.out.println(printDungeon);
            printDungeon = "";
        }
    }
    public void setPlayer()
    {
        layout[x][y] = "O";
    }
    public void moveUp()
    {
        if(layout[x-1][y].equals("#"))
        {}
        else
        {
        layout[x][y]=pastLayout;
        pastLayout = layout[x-1][y];
        layout[x-1][y] = currentPostion;
        x--;
        }
    }
    public void moveDown()
    {
        if(layout[x+1][y].equals("#"))
        {}
        else
        {
        layout[x][y]=pastLayout;
        pastLayout = layout[x+1][y];
        layout[x+1][y] = currentPostion;
        x++;
        }
    }
    public void moveLeft()
    {
        if(layout[x][y-1].equals("#"))
        {}
        else
        {
        layout[x][y]=pastLayout;
        pastLayout = layout[x][y-1];
        layout[x][y-1] = currentPostion;
        y--;
        }
    }
    public void moveRight()
    {
        if(layout[x][y+1].equals("#"))
        {}
        else
        {
        layout[x][y]=pastLayout;
        pastLayout = layout[x][y+1];
        layout[x][y+1] = currentPostion;
        y++;
        }
    }
}

Answer 1

EDIT: This assumes you are making a GUI using javafx. I'm not sure if it works in the command line, but probably not :/

EDIT 2: A minor thing, but if you are updating the layout after each case you can instead just update the layout outside the scope of the if/else. It is good practice to factor out code and avoid copy-paste coding

There is a very simple way to do this using EventHandlers and KeyEvents!

This is an implementation that uses a switch statement. You can replace the switch with an if/else block if that suits you better, but if you don't know switch statements and do want to advance your knowledge of coding definitely look into them!

import javafx.event.EventHandler;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
public class SomeClass {
    public SomeClass() {
        //constructor elided
    }
    //Within your class containing your methods, have this private class.
    private class KeyHandler implements EventHandler<KeyEvent> {
        @Override
        public void handle(KeyEvent e) {
            KeyCode keyPressed = e.getCode();

            switch (keyPressed) {

            case W:
                //do W thing
                break;
            case A:
                //do A thing
                break;
            case S:
                //do S thing
                break;
            case D:
                //do D thing
                break;
            default:
                break;
            }
        }
    }
}

Best of luck! Have fun coding! p.s. You can take out the "// TODO Auto-generated method stub" comment––That is just there as a note from the editing software that the method needs to be filled in!