Question

Write a Java method that takes an input string and computes the income minus the expenses. The income components are indicated by numbers; while the expenses from your spending are numbers starting with a minus sign '-'.

The input string may contain lowercase and uppercase letters, as well as other characters.

Note that Character.isDigit(char) tests if a char is one of the chars '0', '1', ..., '9'. Also recall that Integer.parseInt(string) converts a string to an int.

Test cases : calcNetIncome("salary 15000yuan bonus2000 rent -1000Y") → 16000 calcNetIncome("25000 gross income, -200 water, electricity:-300") → 24500

Answer 1

/* Java class */
public class Main{
        /* This function calculates the net income */ 
        /* Param: An alphanumeric string <s>*/
        /* Return: An integer number <net>, denoting net income */
        public int calcNetIncome(String s){
                /* declare variables */
                int len, i, net = 0;
                String num = "";
                
                /* find length of string */
                len = s.length();
                
                /* check for each character */
                for(i = 0; i <len; i++){
                        /* if characters are digits or -, concatenate */
                        if (((int)s.charAt(i) >= 48 && (int)s.charAt(i) <= 57) || (int)s.charAt(i) == 45){
                                num += s.charAt(i);
                        }
                        else{
                                /* if a string of digits and - found */
                                /* convert to integer and add to sum */
                                if(num.length() > 0){
                                        net += Integer.parseInt(num);
                                        /* make string empty */
                                        num = ""; 
                                }
                        }
                }
                /* End of string reached while reading an integer */
                if(num.length() > 0)
                        net += Integer.parseInt(num);
                
                /* return net income */
                return net;
        }
        public static void main(String[] args){
                /* declare object */
                Main obj = new Main();
                
                /* declare variables */
                int result;
                
                /* call the function */
                result = obj.calcNetIncome("25000 gross income, -200 water, electricity:-300");
                
                /* display the result */
                System.out.print("Net income: "+result);
        }
}

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Net income: 24500

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