Please check my program if it is correct

[mastdesi]

I have to do my first assignment for my java class for friday this week. So due in 3 days. I wrote the polynomial class but haven't done the driver for it yet as i don't know if my polynomial class is good. Please check and let me know if i have done correctly according to my assignment details (assignment pdf file is attached). I am missing the numberOfTerms as i can't seem to figure that out.

Please help me out.

Polynomial.java

public class Polynomial
{
	private int[] coeff = new int[5];
	public Polynomial()
	{
		coeff = null;
	}
	// constructor with 5 parameter 
	public Polynomial(int c0, int c1, int c2, int c3, int c4)
	{
		this.coeff[0] = c4;
		this.coeff[1] = c3;
		this.coeff[2] = c2;
		this.coeff[3] = c1;
		this.coeff[4] = c0;
	}
	// copy constructor  
	public Polynomial(Polynomial p)
	{
		coeff = p.coeff;

	}
	
	// Get Method
	public int getCoeff(int i)
	{
		return this.coeff[i];
	}
	
	// Set Method
	public boolean setCoef(int pos, int num)
	{
		if (pos <= 4 || pos >= 0 )
			{
			coeff[pos] = num;
			return true;
			}
		else
			return false;
	}

	// toString
	public String toString()
	{
		return coeff[4]+"X4"+" + "+coeff[3]+"X3"+" + "+coeff[2]+"X2"+" + "+coeff[1]+"X"+" + "+coeff[0];
	}
	
	// Equals
	public boolean equals(Polynomial p)
	{
		if ((p.coeff[4] != coeff[4]) ||(p.coeff[3] != coeff[3]) ||(p.coeff[2] != coeff[2]) ||(p.coeff[1] != coeff[1]) ||(p.coeff[0] != coeff[0]) )
			return false;
		return true;
	}
	
	// Add
	public Polynomial add(Polynomial p)
	{
		return (new Polynomial(p.coeff[4]+coeff[4],p.coeff[3]+coeff[3],p.coeff[2]+coeff[2],p.coeff[1]+coeff[1],p.coeff[0]+coeff[0]));
	}

	// Derivative
	public Polynomial derive()
	{
		return (new Polynomial(coeff[4]*4,coeff[3]*3,coeff[2]*2,coeff[1],0));
	}

	// Evaluate
	public double evaluate(double x){
		return coeff[4]*x*x*x*x+coeff[3]*x*x*x+coeff[2]*x*x+coeff[1]*x+coeff[0];
	}

}