Cant get collisions to work for Mario-like game - processing

Question

so, I've spent a fair few hours on my Mario-like game but recently I've been stuck on the collisions after I changed to an object based collision system that seems like it should work but there is a bug somewhere that i cant find.
currently the box that represents the player just falls straight through the platform rather than sitting on the platform
You wont be able to run this snippet because I'm new to stack overflow and couldn't find anything closer to processing.
Here is the box class that has all my collision detection
//Box class -- THIS IS WHERE I NEED HELP -- everything else is just for context
//Box class
class Box {
private float xpos, ypos, sizeX, sizeY;
private float bottom = ypos + sizeY;
private float top = ypos;
private float left = xpos;
private float right = xpos + sizeX;
Box(float startX, float startY, float xSize, float ySize) {
boxes++;
xpos = startX;
ypos = startY;
sizeX = xSize;
sizeY = ySize;
}
void update() {
rect(xpos, ypos, sizeX, sizeY);
}
void collision() {
//If on box level
if (player.playerY + player.playerHeight >= top && player.playerY <= bottom) {
//Left Side
if ((player.playerX + player.playerWidth) <= left && (player.playerX + player.playerWidth) + speed >= left) {
player.playerX = left - player.playerWidth;
player.canMoveRight = false;
}
//Right Side
if (player.playerX >= right && player.playerX + speed <= right) {
player.playerX = right;
player.canMoveLeft = false;
}
}
//If in box Y coord
if (player.playerX + player.playerWidth >= left && player.playerX <= right) {
//top
if (player.playerY + player.playerHeight <= top && player.playerY + player.yVelocity + gravity >= top) {
player.Gravity = false;
player.playerY = top - player.playerHeight;
player.yVelocity = 0;
player.canMoveDown = false;
}
//bottom
if (player.playerY + player.yVelocity >= bottom && player.playerY + player.yVelocity + gravity <= bottom) {
player.canMoveUp = false;
player.yVelocity = 0;
player.playerY = bottom;
}
}
//onGround
if (player.playerY == ypos - player.playerHeight) {
player.onGround = true;
}
}
}
Control structure for multiple keypresses
//Control structure to enable multiple keypresses
//Control
float speed = 4;
float gravity = 1;
float jump = 10;
boolean isUp, isLeft, isDown, isRight;
void control() {
//Controls
if (isUp) {
if (player.canMoveUp) {
if (player.onGround) {
player.Gravity = true;
player.yVelocity = 0 + jump;
player.onGround = false;
}
}
}
if (isDown) {
if (player.canMoveDown) {
}
}
if (isRight) {
if (player.canMoveRight) {
player.playerX += speed;
}
}
if (isLeft) {
if (player.canMoveLeft) {
player.playerX -= speed;
}
}
if (player.onGround) {
player.Gravity = false;
player.yVelocity = 0;
}
}
void keyPressed() {
setMove(keyCode, true);
}
void keyReleased() {
setMove(keyCode, false);
}
boolean setMove(int k, boolean b) {
switch (k) {
case UP:
return isUp = b;
case DOWN:
return isDown = b;
case LEFT:
return isLeft = b;
case RIGHT:
return isRight = b;
default:
return b;
}
}
Main tab, box/entity updates and player class
//Main tab
float boxes = 0;
//Calls classes
Box b = new Box(0, 700, 800, 100);
Box b1 = new Box(300, 675, 25, 25);
Player player = new Player(50, 400, 20, 20);
void setup() {
size(800, 800);
frameRate(60);
}
void draw() {
background(255, 255, 255);
boxesUpdate();
boxesCollision();
entityUpdate();
control();
println(player.playerX + ", " + player.playerY);
println(player.yVelocity + ", " + player.Gravity + ", " + player.onGround + ", " + player.canMoveDown);
}
//Box collision update method for when i add more boxes
void boxesCollision() {
player.Gravity = true;
player.canMoveUp = true;
player.canMoveDown = true;
player.canMoveLeft = true;
player.canMoveRight = true;
player.onGround = false;
b.collision();
b1.collision();
if (player.Gravity) {
player.playerY += player.yVelocity;
player.yVelocity += gravity;
}
}
//Along with another update method for the other parts of the boxes
void boxesUpdate() {
b.update();
b1.update();
}
//Entity update method to update players and for when i add NPCs and enemies
void entityUpdate() {
player.update();
}
//Player class
class Player {
private float playerX, playerY, playerWidth, playerHeight;
private float yVelocity = 0;
private float xVelocity = 0;
private boolean canMoveRight, canMoveLeft, canMoveUp, canMoveDown;
private boolean onGround, Gravity;
Player(float X, float Y, float xSize, float ySize) {
playerWidth = xSize;
playerHeight = ySize;
playerX = X;
playerY = Y;
}
void update() {
rect(playerX, playerY, playerWidth, playerHeight);
}
}