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1. BLUE PELICAN JAVA TEXTBOOK ANSWERS KEY EXERCISE 16 CODE
2. BLUE PELICAN JAVA TEXTBOOK ANSWERS KEY EXERCISE 16 PLUS

However, this code breaks on the third pass, because "1345 - 137" is clearly not an integer value. first pass, temp = "1345 - 137", code breaks at Integer.parseInt(temp) You would typically use Integer.parseInt() to turn a String to an int, like so: // start with + In the above example, temp would first be "8" (note that it's a String here), then "33" on the next pass, then "1345 - 137" on the third pass. You can still pull this off with one loop, but it will require some intermediate steps. How can you account for mixed operators? int sum = 0

Now, let's look at your sample input: 8 + 33 + 1345 - 137.

BLUE PELICAN JAVA TEXTBOOK ANSWERS KEY EXERCISE 16 PLUS

Since these values don't change (they are constants), and (in a real program) would be used multiple times in different places, we typically store these in their own final variables: final String PLUS = "\\s*\\+\\s*" // by convention, constants in java are named with all caps Since you are only dealing with + and -, your delimiters are "\\s*\\+\\s*" and "\\s*\\-\\s*", respectively. and so on additionally, you're probably not worried about input checking (making sure there are no letters/symbols/etc) or negative numbers, so we'll ignore those scenarios. Since you haven't learned about arrays yet and are working with a Scanner with a delimiter pattern, we'll have to work around this constraint.įirst, for the purposes of a school assignment, we can probably safely assume that your inputs will follow a particular pattern, along the lines of: (number)(operator)(number)(operator)(number). I'm going to help you answer this in a way that's (hopefully) consistent with what you've learned so far. Now we convert the String to a scanner because we will be using Scanner methodsĬan anybody help me solve the problem (First comment in my source code)? Here is my source code: //I can't get it to work if I use subtraction and addition at the same time but they work separately Now modify the program as to allow either plus or minus signs a minus sign surrounded by any amount of white space. Set delimiters to a plus sign surrounded by any amount of white space.or. object otherwise, it can get stuck waiting for input. String s = kb.nextLine( ) //Best to store in a String and then create a new Scanner So my teacher gave me an assignment to do (will be shown below) and I tried to do it but just could not figure it out, here's the assignment:Ĭonsider the following program that allows something like 8 + 33 + 1,345 + 137 to be entered as String input from the keyboard, A Scanner object then uses the plus signs (and any adjoining white space) as delimiters and produces the sum of these numbers (1523).