java 将两个字符串做数字相加，并返回字符串

雨点打透心脏的1/2处 2022-11-18 13:49 242阅读 0赞

题目描述：传入的两个字符串都不能转为整型或长整型直接相加。

import java.util.LinkedList;
    
    /** * @author mazhen * @className Test * @Description 将两个字符串做数字相加，并返回字符串 * @date 2021/4/9 19:38 */
    public class Test { 
    
        public static String strSum (String str1,String str2) { 
            if (null == str1 || null == str2) { 
                return null;
            }
            char[] chars1 = str1.toCharArray();
            char[] chars2 = str2.toCharArray();
            LinkedList<Integer> intList1 = new LinkedList<>();
            LinkedList<Integer> intList2 = new LinkedList<>();
            for (char value : chars1) { 
                intList1.add(Integer.parseInt(String.valueOf(value)));
            }
            for (char c : chars2) { 
                intList2.add(Integer.parseInt(String.valueOf(c)));
            }
            int sum; //逆序遍历的每一位之和
            int more = 0;//逆序遍历的每一位之和后的进位
            LinkedList<Integer> resultList = new LinkedList<>();
            while (!intList1.isEmpty() || !intList2.isEmpty()) { 
                Integer int1 = intList1.pollLast(); //从尾部取
                Integer int2 = intList2.pollLast(); //从尾部取
                sum = (null == int1 ? 0 : int1) + (null == int2 ? 0 : int2) + more;
                more = sum/10;
                sum = sum%10;
                resultList.addFirst(sum);
            }
            resultList.addFirst(more); //最后记得把进位放入队列
            Object[] objects = resultList.toArray();
            StringBuilder stringBuilder = new StringBuilder();
            for (Object object : objects) { 
                stringBuilder.append(object);
            }
            return stringBuilder.toString();
        }
    
        public static void main(String[] args) { 
            String str1 = "876";
            String str2 = "9834";
            System.out.println(strSum(str1,str2));
        }
    
    }