请用Java语言写一个一元稀疏多项式，并且可以输入并建立多项式，多项式a和b相加,建立多项式a+b

好的，以下是示例代码：

import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class SparsePolynomial {
    private ArrayList<Term> terms;

    public SparsePolynomial() {
        terms = new ArrayList<Term>();
    }

    public void addTerm(int coefficient, int exponent) {
        if (coefficient != 0) {
            terms.add(new Term(coefficient, exponent));
        }
    }

    public SparsePolynomial add(SparsePolynomial other) {
        SparsePolynomial result = new SparsePolynomial();
        int i = 0, j = 0;
        while (i < terms.size() && j < other.terms.size()) {
            Term term1 = terms.get(i);
            Term term2 = other.terms.get(j);
            if (term1.exponent == term2.exponent) {
                int coefficient = term1.coefficient + term2.coefficient;
                result.addTerm(coefficient, term1.exponent);
                i++;
                j++;
            } else if (term1.exponent > term2.exponent) {
                result.addTerm(term1.coefficient, term1.exponent);
                i++;
            } else {
                result.addTerm(term2.coefficient, term2.exponent);
                j++;
            }
        }
        for (; i < terms.size(); i++) {
            result.addTerm(terms.get(i).coefficient, terms.get(i).exponent);
        }
        for (; j < other.terms.size(); j++) {
            result.addTerm(other.terms.get(j).coefficient, other.terms.get(j).exponent);
        }
        return result;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        Collections.sort(terms);
        boolean firstTerm = true;
        for (Term term : terms) {
            if (term.coefficient > 0 && !firstTerm) {
                sb.append("+");
            }
            sb.append(term.coefficient);
            if (term.exponent > 1) {
                sb.append("x^").append(term.exponent);
            } else if (term.exponent == 1) {
                sb.append("x");
            }
            firstTerm = false;
        }
        return sb.toString();
    }

    private static class Term implements Comparable<Term> {
        private int coefficient;
        private int exponent;

        public Term(int coefficient, int exponent) {
            this.coefficient = coefficient;
            this.exponent = exponent;
        }

        @Override
        public int compareTo(Term other) {
            return other.exponent - exponent;
        }
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        SparsePolynomial a = new SparsePolynomial();
        SparsePolynomial b = new SparsePolynomial();
        System.out.println("请输入多项式a的项数：");
        int na = scanner.nextInt();
        for (int i = 0; i < na; i++) {
            System.out.println("请输入a的第" + (i+1) + "项的系数和指数：");
            int coefficient = scanner.nextInt();
            int exponent = scanner.nextInt();
            a.addTerm(coefficient, exponent);
        }
        System.out.println("请输入多项式b的项数：");
        int nb = scanner.nextInt();
        for (int i = 0; i < nb; i++) {
            System.out.println("请输入b的第" + (i+1) + "项的系数和指数：");
            int coefficient = scanner.nextInt();
            int exponent = scanner.nextInt();
            b.addTerm(coefficient, exponent);
        }
        SparsePolynomial c = a.add(b);
        System.out.println("多项式a为：" + a);
        System.out.println("多项式b为：" + b);
        System.out.println("多项式a+b为：" + c);
    }
}

运行程序后，会要求依次输入多项式a和b的项数，然后输入每一项的系数和指数。程序会根据输入的多项式建立SparsePolynomial对象，并调用add方法计算a+b，最后输出结果。