栈的应用2——大数相加

public class Example3_2LargeNumAdd {
//大数相加
	/**
	 * 栈的应用实例
	 * 大数相加
	 *
	 * 
	 * */
	public String add(String a,String b) throws Exception{
		LinkStack sum = new LinkStack();
		LinkStack sA = numSplit(a);
		LinkStack sB = numSplit(b);
		int partiaSum;            //两个位求和   
		boolean isCarry = false;  //进位标示
		while(! sA.isEmpty() && ! sB.isEmpty()){
			partiaSum = (Integer)sA.pop() + (Integer)sB.pop();
			if(isCarry){
				partiaSum++;
				isCarry = false;
			}
			if(partiaSum >= 10){
				partiaSum -= 10;
				sum.push(partiaSum);
				isCarry = true;
			}else{
				sum.push(partiaSum);
			}
		}
		LinkStack temp = !sA.isEmpty()?sA:sB;
		while(!temp.isEmpty()){
			if(isCarry){
				int t = (Integer)temp.pop();
				++t;
				if(t >= 19){
					t -= 10;
					sum.push(t);
				}else{
					sum.push(t);
					isCarry = false;
				}
			}else{
				sum.push(temp.pop());
			}
		}
		if(isCarry){
			sum.push(1);
		}
		String str = new String();
		while(!sum.isEmpty()){
			str = str.concat(sum.pop().toString());
		}
		return str;
	}
	
	public LinkStack numSplit(String str)throws Exception{
		LinkStack s = new LinkStack();
		for(int i = 0;i < str.length(); i++){
			char c = str.charAt(i);
			if( ' ' == c){
				continue;
			}else if('0' <= c && '9' >= c){
				s.push(Integer.valueOf(String.valueOf(c)));
			}else{
				throw new Exception("非法字符");
			}
		}
		return s;
	}
	public static void main(String[] args)throws Exception {
		// TODO Auto-generated method stub
		Example3_2LargeNumAdd e = new Example3_2LargeNumAdd();
		System.out.println(e.add("12345612134885","2186416457934345"));

		

	}

}