How to convert a string that contains an asterisk to an integer?

Question

I have a string

String numAsString = "8 * 9";

And I want to convert this into an integer, so when I print the integer

int numAsInt = (the code I am asking for);
System.out.println(numAsInt);

The output would be

I have tried parseInt and valueOf, but both give an exception cause of the asterisk. If you don't know, the asterisk means multiplication.
Is there a way to do this?

score 4 · Answer 1 · answered Oct 20 '18 at 17:02

4

Parse string by asterisk and multiply parts:

String input = "8 * 9";
String parts[] = input.split("\\*");
int result = 1;
for(String part : parts)
    result *= Integer.parseInt(part.trim());
System.out.println(result);

answered Oct 20 '18 at 17:02

Rahim Dastar

1,259
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Thanks, this works. – AwesomeMaster Oct 20 '18 at 19:41
Your welcom :) isn’t acceptable?! – Rahim Dastar Oct 20 '18 at 20:28
?? What do you mean, isn't acceptable? – AwesomeMaster Oct 22 '18 at 00:50

Amin · Accepted Answer · 2018-10-20T19:44:19.273

-1

You can use something like this and it is easy:

String[] values = numAsString.split("\\*");
numAsInt = Integer.valueOf(values[0].trim()) * Integer.valueOf(values[1].trim());

but If you have a calculation or something with parenthesis, plus, minus and etc, you can use this: Running JavaScript code in java
I think this help you.

edited Oct 20 '18 at 19:44

answered Oct 20 '18 at 17:02

Amin

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You might want to check to see if your example actually works. – Andy Turner Oct 20 '18 at 17:13
Thanks for comment. I write it without IDE but I forget about special meaning of * in regex – Amin Oct 20 '18 at 17:16
Thanks, this helped. I'm fine with this because I am not using parentheses. – AwesomeMaster Oct 20 '18 at 17:18
For some reason, when I have the variables stated at the very top and then I use them in a function, it gives me a NullPointerException. How can I fix this? And what causes it? – AwesomeMaster Oct 20 '18 at 18:46
@AwesomeMaster can you explain more? is it related to this question too? – Amin Oct 20 '18 at 19:23
Yes it is related. When I say the variables, I mean the code you gave me there. The String array and the numAsInt code. – AwesomeMaster Oct 20 '18 at 19:40
Currently I am using @Rahim code while waiting for your response. – AwesomeMaster Oct 20 '18 at 19:41
does your input in format "9 * 8" with spaces? if not this doesn't work. I change it to work for "9*8" too. `trim()` will remove space from beginning and end of string. – Amin Oct 20 '18 at 19:44
Yes, my input has spaces in it. – AwesomeMaster Oct 20 '18 at 20:04
so with my edit, which much same as @Rahim , now it works for handling spaces. – Amin Oct 20 '18 at 20:06

How to convert a string that contains an asterisk to an integer?

2 Answers2