123456789 随机加减等于100

package Day725;

import java.util.Random;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Demo04 {
    //正则表达式 123456789 随机加减等于100
    public static void main(String[] args) {
        while (true){
            String str=getStr();
            if (sum(str)==100){  //判断加减是否等于100
                System.out.printf("%s=%d",str,sum(str));
                break;
            }
        }
    }
    public static int sum(String str){    //方法
        int sum=0;
        Pattern p= Pattern.compile("[0-9]+|\-[0-9]+");
        Matcher m=p.matcher(str);
        while (m.find()){
            sum+=Integer.parseInt(m.group());
        }
        return sum;
    }
    public  static String getStr() {    //方法
        StringBuffer sbu = new StringBuffer();
        String[] op = {"+", "-", ""}; 
        Random rand = new Random(); //随机加减
        for (int i = 1; i < 9; i++) {
            sbu.append(i+op[rand.nextInt(op.length)]);
        }
        sbu.append(9);
        return sbu.toString();
    }
}