Thread: How can I improve on this?

I'm not sure if this is the right thread, but I'm not sure where to post. I just want information on things like if I'm writing it in a bad way or maybe theres an easier way.
PLEASE DON'T GIVE ME THE AWNSER. I don't wanna be spoon fed. Give me a simple nudge so I get my brain thinking its a much better learning technique. The code in it self runs fine although my crappy collision detection which I used pointers for sucks.

Basically I just want to know why my code sucks.
How I can improve it.
If I'm using methods or calling stuff or other things I don't need.
I know the walls are dumb an I'll make a new class for level and make a code in there so I can create walls much easier.

I might be confusing you guy, but I'm only wondering how to improve my code and organize it better so I can keep on coding a very simple game. I don't know what it is even going to do yet. It's all for learning as a I have a bigger idea for a game that isn't out of my way.

Screen.java

package com.projectgaming.game1;
 
import java.awt.Color;
import java.awt.event.KeyListener;
 
import javax.swing.JFrame;
 
public class Screen {
 
	private static final long serialVersionUID = 1L;
 
	public static int w = 800;
	public static int h = 600;
 
	public static void main(String[] args){
		Game g = new Game();
		JFrame frame = new JFrame();
		frame.add(g);
		frame.pack();
		frame.setResizable(false);
		frame.setSize(w, h);
		frame.setTitle("Game Test");
		frame.setBackground(Color.BLACK);
		frame.setVisible(true);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setLocationRelativeTo(null);
	}
}

Game.java

package com.projectgaming.game1;
 
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
 
import javax.swing.*;
 
public class Game extends JPanel implements Runnable, KeyListener{
 
	private static final long serialVersionUID = 1L;
 
	public Rectangle character;
	public Rectangle floor;
	public Rectangle wall1;
	public Rectangle wall2;
	public Rectangle wall3;
	public Rectangle wall4;
 
	public int keyUp = KeyEvent.VK_W;
	public int keyDown = KeyEvent.VK_S;
	public int keyRight = KeyEvent.VK_D;
	public int keyLeft = KeyEvent.VK_A;
 
	public int characterWidth = 24;
	public int characterHeight = 36;
	public int characterX = 400;
	public int characterY = 300;
 
	public int floorWidth = 400;
	public int floorHeight= 300;
	public int floorX = 200;
	public int floorY= 200;
 
	public int wall1Width = 400;
	public int wall1Height = 10;
	public int wall1X = 200;
	public int wall1Y = 200;
 
	public int wall2Width = 10;
	public int wall2Height = 300;
	public int wall2X = 600;
	public int wall2Y = 200;
 
	public int wall3Width = 410;
	public int wall3Height = 10;
	public int wall3X = 200;
	public int wall3Y = 500;
 
	public int wall4Width = 10;
	public int wall4Height = 300;
	public int wall4X = 200;
	public int wall4Y = 200;
 
	public int movementSpeed = 1;
	public int movementFrame = 0;
 
	public boolean running = true;
	public boolean objectsDefined = false;
 
	public boolean alive = true;
 
	public boolean up = false;
	public boolean down = false;
	public boolean right = false;
	public boolean left = false;
	public boolean moving = false;
 
	public Thread game;
 
	public Game(){
		super();
		game = new Thread(this);
		game.start();
 
		defineObjects();
		setFocusable(true);
		addKeyListener(this);
	}
 
	public void keyPressed(KeyEvent e){
		//System.out.println("Key pressed");
		if(e.getKeyCode() == keyUp){
			up = true;
		}
 
		if(e.getKeyCode() == keyDown){
			down = true;
		}
 
		if(e.getKeyCode() == keyLeft){
			left = true;
		}
 
		if(e.getKeyCode() == keyRight){
			right = true;
		}
	}
	public void keyReleased(KeyEvent e){
		if(e.getKeyCode() == keyUp){
			up = false;
		}
 
		if(e.getKeyCode() == keyDown){
			down = false;
		}
 
		if(e.getKeyCode() == keyLeft){
			left = false;
		}
 
		if(e.getKeyCode() == keyRight){
			right = false;
		}
	}
	public void keyTyped(KeyEvent e){}
 
	public static void main(String[] args){
		new Game();
	}
 
	public void defineObjects(){
		character = new Rectangle(characterX, characterY, characterWidth, characterHeight);
		floor = new Rectangle(floorX, floorY, floorWidth, floorHeight);
		wall1 = new Rectangle(wall1X, wall1Y, wall1Width, wall1Height);
		wall2 = new Rectangle(wall2X, wall2Y, wall2Width, wall2Height);
		wall3 = new Rectangle(wall3X, wall3Y, wall3Width, wall3Height);
		wall4 = new Rectangle(wall4X, wall4Y, wall4Width, wall4Height);
 
		objectsDefined = true;
 
		repaint();
	}
	public void paintComponent(Graphics g){
		super.paintComponent(g);
 
		this.setBackground(Color.BLACK);
 
		if(objectsDefined){
			g.setColor(Color.RED);
			g.fillRect(floor.x, floor.y, floor.width, floor.height);
 
			g.setColor(Color.BLUE);
			g.fillRect(wall1.x, wall1.y, wall1.width, wall1.height);
			g.fillRect(wall2.x, wall2.y, wall2.width, wall2.height);
			g.fillRect(wall3.x, wall3.y, wall3.width, wall3.height);
			g.fillRect(wall4.x, wall4.y, wall4.width, wall4.height);
 
			if(alive){
				g.setColor(Color.WHITE);
				g.fillRect(character.x, character.y, character.width, character.height);
			}
		}
		repaint();
	}
 
	public void run() {
		while(running){
 
			Point rightFoot = new Point(character.x, (character.y + 1) + character.height);
			Point leftFoot = new Point(character.x + character.width, character.y + character.height);
			Point rightHand = new Point(character.x, character.y - 1);
			Point leftHand = new Point(character.x - 1, character.y);
			//Movement
			if(movementFrame >= movementSpeed){
					if(up){
						if(wall1.contains(rightHand) || wall1.contains(leftHand)){}else{
							character.y -= 1;
						}
					}
 
					if(down){
						if(wall1.contains(rightFoot) || wall1.contains(leftFoot)){}else{
							character.y += 1;
						}
					}
 
					if(left){
						if(wall1.contains(leftHand) || wall1.contains(leftFoot)){}else{
							character.x -= 1;
						}
					}
 
					if(right){
						if(wall1.contains(rightHand) || wall1.contains(rightFoot)){}else{
							character.x += 1;
						}
					}	
					movementFrame = 0;
				}else{
					movementFrame += 1;
				}
			try {
				Thread.sleep(1);
			} catch (Exception e) {
			}
 
			repaint();
		}
	}
}

A few suggestions from my point of view:
1. Class Variables that you intend on ONLY being used inside of the class, should be set to private instead of public (or protected if you think the variable will need to be inherited at some point in the future).
2. Instead of having different variables for the keyUp, keyDown, ect., you could instead just use constants (eg: KeyEvent.VK_W) and check each one using a switch statement. I suspect you created variables for them for readability and, if so, commenting is a better alternative to creating variables for each constant.
3. Instead of having a boolean whose entire purpose is to check if variables have been initialized, do a check if(wall1!=null) in your paint method instead of if(objectsDefined).
4. Why are you repainting in the paintComponent() method?
5. Instead of having a blank if statement for the purpose of having an else statement (in your run() method), check the negative case in your if statement. Check out the sudo-code below:

this:
if(somecase) {
     do nothing;
} else {
     do something;
}
 
is the same as:
if(!somecase) {
     do something;
}

6. If the values of some variables are never going to change, such as the width, height, x, and y of the floor and walls, it is best to make them constants instead of normal variables.

That's all for now. There are probably other things that can be improved upon.

Constants are just values. So, you can say:

switch(someKey) {
case KeyEvent.VK_W:
     do something;
     break;
case KeyEvent.VK_S:
     do something;
     break;
...
}

Don't forget the break statements in a switch.


In your run() method, you have if/elses that look like this:

if(wall1.contains(rightHand) || wall1.contains(rightFoot)){}else{
							character.x += 1;
						}

that can simply be changed to:

if(!(wall1.contains(rightHand) || wall1.contains(rightFoot))){
							character.x += 1;
						}

Instead of sending the switch statement the keyPressed variable, just send it: e.getKeyCode()
e is the KeyEvent parameter of the method.