how to create gravity in java

1    GRAVITY = 10;
2    TERMINAL_VELOCITY = 300;
3    vertical_speed = 0;
4
5    public void fall(){ 
6    this.vertical_speed = this.vertical_speed + GRAVITY;
7    if(this.vertical_speed > TERMINAL_VELOCITY){
8        this.vertical_speed = TERMINAL_VELOCITY;
9    }
10    this.y = this.y - this.vertical_speed;
11}

1const GRAVITY = 10;
2const TERMINAL_VELOCITY = 300;
3
4object Player 
5{
6    int vertical_speed = 0;
7    int vertical_position;  
8
9    function fall ()
10    {
11        this.vertical_speed = this.vertical_speed + GRAVITY;
12        if (this.vertical_speed > TERMINAL_VELOCITY)
13        {
14            this.vertical_speed = TERMINAL_VELOCITY;
15        }
16        this.vertical_position = this.vertical_position - this.vertical_speed;
17    }
18}