привет. у меня проблема .консоль видает ошибку.как я понял чтото не понравилось в условии "если"

import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.lang.*;
class godmos111{
	    private StringBuffer deleter1(StringBuffer str5)
	{   String str = str5.toString();
		String[] words = str.split("/",2);
        Pattern   p ,p1;
        Matcher   m ,m1;
		p = Pattern.compile("\\d+\\.\\d+$");
        m = p.matcher(words[0]);
        p1 = Pattern.compile("^\\d+\\.\\d+");
        m1 = p1.matcher(words[1]);
        while (m.find() && m1.find()){
        String y1= m.group();
        String y2 = m1.group();
        String result1 = words[0].replaceAll(y1, "");
        String result2 = words[1].replaceAll(y2, "");
        StringBuffer result = new StringBuffer();
        result.append(result1 + result2);
        return result;
        }
       return null ;


	}

		private StringBuffer deleter2(StringBuffer str5)
	{   String str = str5.toString();
		String[] words = str.split("*",2);
        Pattern   p ,p1;
        Matcher   m ,m1;
		p = Pattern.compile("\\d+\\.\\d+$");
        m = p.matcher(words[0]);
        p1 = Pattern.compile("^\\d+\\.\\d+");
        m1 = p1.matcher(words[1]);
		while (m.find() && m1.find()){
        String y1= m.group();
        String y2 = m1.group();
        String result1 = words[0].replaceAll(y1, "");
        String result2 = words[1].replaceAll(y2, "");
        StringBuffer result = new StringBuffer();
        result.append(result1 + result2);
        return result;
        }
   return null ;

		}

private Double delet(StringBuffer r2){
String r = r2.toString();
String[] words = r.split("/", 2);
Pattern p, p1;
Matcher m, m1;
p = Pattern.compile("\\d+\\.\\d+$");
m = p.matcher(words[0]);
p1 = Pattern.compile("^\\d+\\.\\d+");
m1 = p1.matcher(words[1]);

while (m.find() && m1.find()) {
String y1 = m.group();
String y2 = m1.group();
double tmp1 = Double.parseDouble(y1);
double tmp2 = Double.parseDouble(y2);
return tmp1 / tmp2;
}


	return null ;
}
private Double doubleplus(StringBuffer r2){

String r=r2.toString();

String[] words1 = r.split("*",2);
Pattern   p ,p1;
Matcher   m ,m1;
p = Pattern.compile("\\d+\\.\\d+$");
m = p.matcher(words1[0]);
p1 = Pattern.compile("^\\d+\\.\\d+");
m1 = p1.matcher(words1[1]);

while (m.find() && m1.find() ){
String y1=m.group();
String y2=m1.group();
double tmp1 = Double.parseDouble(y1);
double tmp2 = Double.parseDouble(y2);
return tmp1*tmp2;
}
return null ;
}


	public String str1 = "5+5-9/9";
	StringBuffer str0 = new StringBuffer(str1);
    private StringBuffer calculate (StringBuffer str)

	 {

int a=0;
while(str.indexOf("/")!=-1 | str.indexOf("*")!=-1 && a<10 ){

a++;
		 if(str.indexOf("/") < str.indexOf("*") && str.indexOf("/")!=-1  |  str.indexOf("*")!=-1)
{int a1 = str.indexOf("/");
int a2 = a1+1;
int a3 = a1-1;
double tmp3=delet(str);
deleter1(str);
str.insert(a3,tmp3);
  System.out.print(str);

		 }
		 if(str.indexOf("*") < str.indexOf("/") && str.indexOf("*")!=-1   |  str.indexOf("/")!=-1)
{int a4 = str.indexOf("*");
int a5 = a4+1;
int a6 = a4-1;
double tmp6=doubleplus(str);
deleter2(str);
str.insert(a6,tmp6);
		 }

		 }
		 return str;
}

	StringBuffer f1 = calculate(str0);


	public static void main (String[] args) {
		godmos111 gm = new godmos111();
        System.out.print(gm.f1);



	}
}