java 递归加减法

有时候设计到list map 做交集，并集等操作。

可以参考加减法的实现

 

public class Test {

	/**
	 * @param args
	 */
	
	public static final char y_all='+';
	public static final char y_diff='-';
	public static final char y_and='&';		// 不使用
	
	// 思路是 通过运算符 拆分左右二边,然后左右2变进行运算  递归操作
	public static void main(String[] args) {
		String s = "((1+2)-(3-4))+((0+1)-(2-1))";
		String s1 ="((10+2)-3)+(5-2)";
		
		System.out.println(getall(s1));
	}

	public static int getall(String rel){
		
		// 判断最小单位
		if(rel.indexOf("(")==-1 && rel.indexOf(")")==-1 && rel.indexOf(y_all)==-1 && rel.indexOf(y_diff)==-1){
			return getUser(rel);
		}else{
			String left = getLeft(rel);
			System.out.println("left: "+left);
			String right = getRight(rel);
			System.out.println("right: "+right);
			
			String op = getOP(rel);
			System.out.println("op: "+op);
			
			return Oper(getall(left), getall(right), op);
		
		}
	}
	
	public static String getLeft(String rel){
		int index=0;
		int sub = getSub(rel, index);
		String str = rel.substring(0,sub);
		return clearK(str);
	}
	
	
	public static String getRight(String rel){
		int index=0;
		int sub = getSub(rel, index);
		String str = rel.substring(sub+1);
		return clearK(str);
	}
	
	public static String getOP(String rel){
		int index=0;
		int sub = getSub(rel, index);
		String str = rel.substring(sub,sub+1);
		return str;
	}
	
	public static int Oper(int left,int right,String op){
		int tmp=0 ;
		if(op.equals("+")){
			tmp = left+right;
		}else if(op.equals("-")){
			tmp = left-right;
		}else if(op.equals("&")){
			//TODO:
		}
		return tmp;
	}
	
	public static int getUser(String rel){
		int t =0;
		if(null!=rel && !rel.isEmpty()){
			t = Integer.parseInt(rel);
		}
		return t;
	}
	
	public static String clearK( String rel ) {
		
		if(rel.startsWith("(") && rel.endsWith(")")){
			rel = rel.substring(1,rel.length()-1);
		}
		return rel;
		
	}
	
	
	private static int getSub(String rel, int index) {
		int sub =0;
		char[] clt = rel.toCharArray();
		for(int i=0;i<clt.length;i++){
			char c = clt[i];
			if(c=='('){
				index++;
			}
			if(c==')'){
				index--;
			}
			if(c==y_all){
				if(index==0){
					sub = i ;
					break;
				}
			}
			if(c==y_diff){
				if(index==0){
					sub = i ;
					break;
				}
			}
			if(c==y_and){
				if(index==0){
					sub = i ;
					break;
				}
			}
		}
		return sub;
	}
}