Hi all, I just make a program and I get in trouble about set method.so anyone can help me?

import java.util.LinkedList;
public class Polynomial 
{

	private LinkedList<Integer> coeff = new LinkedList<Integer>();
	private int deg = 0;
	/* Constructs a new polynomial of degree zero */
	public Polynomial()
	{
        
	}

	/* Returns an integer representing the coefficient 
	 * of the x^power term 
	 */
	int getCoefficients(int power) 
	{
		return coeff.get(power);
	}

	/* Sets the coefficient of the x^power term to coef.*/ 
	void setCoefficients(int coef, int power) 
	{
		
	}	
	/* Returns the String representation of the polynomial. 
	 * For example, a polynomial can be represented as either
	 * 3 * x^2 + 2 * x + 1 or
	 * 3x^2 + 2x + 1
	 * Any term whose coefficient is zero should not appear
	 * in the string unless the polynomial has only a single
	 * constant term of zero.
	 */
	public String toString() 
	{
		if(deg == 0)
			return "" + coeff.get(0);
		if(deg == 1)
			return coeff.get(1) + "x^ " + coeff.get(0);
		String p = coeff.get(deg) + "x^ " + deg;
		for(int i = deg-1;i>=0;i--)
		{
			if(coeff.get(i) == 0) continue;
			else if (coeff.get(i)> 0) 
				p = p + " + " +(coeff.get(i));
			else if (coeff.get(i) < 0) 
				p = p + " + " +(-coeff.get(i));
			if(i == 1)
				p = p + "x ";
			else if (i >= 1)
				p = p + "x^ " + i;
		}
		return p;
	}

	/* Evaluates the polynomial for the value x and returns
	 * the result p(x).
	 */
	double evaluate(double x) 
	{
		double n = 0;
		for(int i = deg; i>=0; i--)
			n = coeff.get(i) + (x * n);
		return n;
	}

	/* Add to this polynomial the polynomial "other" and
	 * return the resulting polynomial.
	 */
	Polynomial add(Polynomial other) 
	{
        Polynomial a = this;
        Polynomial b = new Polynomial(0, Math.max(a.deg, other.deg));
        for (int i = 0; i <= a.deg; i++) 
        	b.coeff.set(i, b.coeff.get(i) + a.coeff.get(i));
        for (int i = 0; i <= b.deg; i++) 
        	b.coeff.set(i, b.coeff.get(i) + other.coeff.get(i));

        return b;
	}
	/*
	 * This method is to get a * x^b.
	 */
	public Polynomial(int a ,int b)
	{
		setCoefficients(a, b);
	}
	/*
	 * This method is return the power of each coefficient.
	 */
	public int degree()
	{
		int d = 0;
		for(int i = 0; i<=coeff.size();i++)
			if(coeff.get(i)!=0)
				d = i;
		return d;
	}
}

You need to explain what the set method should do, and actually would be nice to know why you want to use setters instead of providing parameter through constructor