bad platformer basic entity

GameObject.java

package com.cascadegames.androidgame;

import android.util.Log;
import jgame.JGObject;

public abstract class GameObject extends JGObject {
	
	AndroidGame g;
	double gravity = 0.9;
	
	boolean stuck = false;
	boolean jumping = false;
	boolean bouncing = false;
	boolean airborne = false;
	boolean left = false;
	double jump = 0;
	
	double maxxspeed = 6;
	double maxyspeed = 8;
	
	private double yacceleration = 0;
	// mostly used for grid-snapping
	private final double kk;
	
	public GameObject(double x, double y, int colid, String gfxname) {
		
		super(gfxname, true, x, y, colid, gfxname, 1.0, 1.0);
		yacceleration = gravity;
		airborne = true;
		
		g = AndroidGame.g;
		kk = 2*g.TILE_SIZE/3;
	}
	
	public void hit_bg(int tilecid) {

		if ( check_collision_top() ) {
			hit_bg_top();
		} else if ( check_collision_bottom() ) {
			hit_bg_bottom();
		}
		
		if ( check_collision_left() ) {
			hit_bg_left();
		} else if ( check_collision_right() ) {
			hit_bg_right();
		}
	}
	
	public boolean check_collision_bottom() {
		return checkBGCollision(0, g.TILE_SIZE-kk) == Collision.TILE;
	}
	
	public boolean check_collision_top() {
		
		return checkBGCollision(0, -(g.TILE_SIZE-kk)) == Collision.TILE;
	}
	
	public boolean check_collision_left() {
		return checkBGCollision(-g.TILE_SIZE, 0) == Collision.TILE;
	}
	
	public boolean check_collision_right() {
		return checkBGCollision(g.TILE_SIZE, 0) == Collision.TILE;
	}

	public void hit(JGObject obj) {
		
		if (checkCollision(1,-3*xspeed,-3*yspeed)==0) {
			// reverse direction
			xspeed = -xspeed;
			yspeed = -yspeed;
		}
	}
	
	public void jump() {
		
		if( !jumping && !check_collision_top() ) {
			jumping = true;
			yspeed = -jump;
		}
	}
	
	public void hit_bg_bottom() {
		snapToGrid(0, kk);
		y -= 0.00000001;
		airborne = false;
		jumping = false;
		yacceleration = 0;
		yspeed = 0;
		bouncing = false;
	}
	
	public void hit_bg_top() {
		snapToGrid(0, kk);
		y += 0.00000001;
		airborne = true;
		jumping = false;
		yacceleration = 0;
		yspeed = -yspeed/8;
		bouncing = true;
	}
	
	public void hit_bg_left() {
		snapToGrid(kk, 0.0);
		
		x += 0.000000001;
		xspeed = 0;
		//bouncing = true;
		
	}
	
	public void hit_bg_right() {
		snapToGrid(kk, 0.0);	
		
		x -= 0.000000001;
		xspeed = 0;
		//bouncing = true;
		
	}
	
	public void move() {

		if(xspeed > maxxspeed) {
			xspeed = maxxspeed;
		}else if(xspeed < -maxxspeed){
			xspeed = -maxxspeed;
		}
		
		super.move();
		
		if(jumping && yspeed >= 0) {
			jumping = false;
		}
		
		if(yspeed + yacceleration >= maxyspeed) { 
			yspeed = maxyspeed;
		} else {
			yspeed += yacceleration;
		}
		
		airborne = !check_collision_bottom();
		if( airborne ) {
			yacceleration = gravity;
			jumping = true;
			
			if ( !check_collision_left() && !check_collision_right()) {
				bouncing = false;
			}
			
		} else if( !jumping ) {
			hit_bg_bottom();
		}
	}
	
	public abstract void paint();
}