Write java program to sum of all integers from a random String

Question

I was asked this question in an interview recently (Java programming que)

• Return the sum of all integers from a random String. Continuous Integers must be considered as one number.
• If the input String does not have any Integers, return 0.
• You may ignore decimals, float, and other non-integer numbers
• @param str : Input String
• • Given the following inputs, we expect the corresponding output:
• "-1a2b3c" => 4 (-1+2+3)
• "123ab!45c" => 168 (123+45)
• "abcdef" => 0 (no Integers in String)
• "0123.4" => 127 (0123+4)
• "dFD$#23+++12@#T1234;/.,10" => 1279 (23+12+1234+10)

I was allowed to use any inbuilt functions as well

I wrote this code , however this seems little more complex. Can this code be done any other way?

public int convertString(String str){
int num=0, currNo = 0;
Boolean isNegative = false;

for (int i=0 ; i<str.length(); i++){
Char t = str.charAt(i) ;

    if(t == ‘-‘){
       if(isNegative)
            num = num-currNo;
        else
            num = num + currNo;

       isNegative=true;
       currNo=0;
    }
    else if(((t-‘0’) <= 9 && (t-‘0’)>=0)){
        currNo = (currNo*10) + t;
    }
    else {

            if(isNegative)
            num = num-currNo;
        else
            num = num + currNo;

        currNo=0;
        isNegative=false;
    }
}


if(isNegative)
            num = num-currNo;
        else
            num = num + currNo;                         
isNegative=true;

return num;
}

Answer 1

Using regex:

Matcher m = Pattern.compile("-?\\d+").matcher(str);
long sum = 0;
while(m.find()) {
    sum += Integer.parseInt(m.group());
}