How would I go about implementing java code in c# and vice versa?

Question

I'm attempting to create a game in unity, but Java isn't able to be used in it, so any premade scripts are in C#. I want to add some stuff in the mechanics of the game, which requires me to alter variables and values in the script, but I only know how to do so in java, so how would I make it so they can effectively communicate?

An example from c#:

    protected override void ComputeVelocity()
{
    Vector2 move = Vector2.zero;

    move.x = Input.GetAxis ("Horizontal");
    if (Input.GetButtonDown ("Jump") && grounded) {
        velocity.y = jumpTakeOffSpeed;
    } else if (Input.GetButtonUp ("Jump"))
    {
        if (velocity.y > 0)
            velocity.y = velocity.y * .5f;
    }

    targetVelocity = move * maxSpeed;

}
}

and my java code:

public void keyPressed(KeyEvent e) 
{
    if(e.getKeyCode() == KeyEvent.VK_SHIFT)
    { 
        endTime = (System.currentTimeMillis() / 1000);
        timePassed = endTime - startTime; 
        if(timePassed >= 2)
        {   

            //try to set a time limit or something 

            velocity = overMaxVelocity;
            //set velocity to above usual max for dodgeTime 
            startTime = dodgeTime + (System.currentTimeMillis() / 1000);
        }


    }

}

I'm trying to make it so when shift is pressed, the velocity is changed to a larger value than usual for a small time, but i have no idea where to even begin

Answer 1

Unity only supports scripts written in C#. It used to also support a version of JavaScript they called UnityScript, but they moved to only officially support C# now. Fortunately C# is really similar to Java, so you shouldn't have too much trouble translating your scripts to C#. The main challenge would be learning the Unity library.

I wrote some code below that updates an object's speed using Unity library functions. Unity has a lot of built-in ways of helping you out as a developer so I'd recommend the tutorials on Unity's website for more on getting started with it.

public float speed = 2;
public float speedUpFactor = 2;

// Get the Rigidbody component attached to this gameobject
// The rigidbody component is necessary for any object to use physics)
// This gameobject and any colliding gameobjects will also need collider components
Rigidbody rb;
// Start() gets called the first frame that this object is active (before Update)
public void Start(){
    // save a reference to the rigidbody on this object
    rb = GetComponent<Rigidbody>();
}
}// Update() gets called every frame, so you can check for input here.
public void Update() {

    // Input.GetAxis("...") uses input defined in the "Edit/Project Settings/Input" window in the Unity editor.
    // This will allow you to use the xbox 360 controllers by default, "wasd", and the arrow keys.
    // Input.GetAxis("...") returns a float between -1 and 1
    Vector3 moveForce = new Vector3(Input.GetAxis ("Horizontal"), 0, Input.GetAxis("Vertical"));
    moveForce *= speed;

    // Input.GetKey() returns true while the specified key is held down
    // Input.GetKeyDown() returns true during the frame the key is pressed down
    // Input.GetKeyUp() returns true during the frame the key is released
    if(Input.GetKey(KeyCode.Shift)) 
    {
        moveForce *= speedUpFactor;
    }
    // apply the moveForce to the object
    rb.AddForce(moveForce);
}