Converting a String with spaces to an Integer in java

Question

I\'m trying to convert a String variable into an integer, only the String looks like this (for example):

String string = \" 12\";

And so the St

Answer 1

Use the string trim function in Java to first get a string without the spaces, then parse it...

1.) Remove spaces with trim ... String#trim

String stringWithoutSpace = string.trim();

2.) Parse the string without spaces ... Integer#parseInt

int integer = Integer.parseInt(stringWithoutSpace);

3.) Do everything above in one step ...

int integer = Integer.parseInt(string.trim());

Answer 2

To make sure that your code does not throw NumberFormatException or even NullPointerException, when you get number from user, use apache common classes:

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;
.....
// '1' is the default value which is returned when the string can not be converted to int
// The StringUtils.trimToEmpty do both left and right trim
int number = NumberUtils.toInt(StringUtils.trimToEmpty( "  12 ",1)) = 12; 

Answer 3

The string split() method works well if you have a string of multiple numbers separated by spaces.

String numbers = "1 23 456";
String[] numbersArray = numbers.split(" "); // splitting string by spaces
System.out.println(numbersArray.toString());
// output ["1","23","456"]

Then you can use Integer.parseInt() on each index of the array. Hope that helps

Answer 4

Would .trim work? And if so, how would I use that?

Yes, trim() will work, it will remove leading and trailing spaces from String,

int integer = Integer.parseInt(string.trim());

Answer 5

If you using Java 11, you can use the String::strip method. For example:

int integer = Integer.parseInt(string.strip());

The strip() method is similar to trim() but uses Character.isWhitespace(int) to resolve spaces. (The Character.isWhitespace(int) method is Unicode-aware.)