How to parse an int from a string java?

Question

I'm trying to parse an int from a dummy String for test reasons. The string will be:

String numOfStudents = "Number of Students: 5";

I want to parse this String, ensuring it contains the line 'Number of Students' as well as finding out the int value.

How can I achieve this? I need the int value to compare it to another int value.

Thanks

possible duplicate of Get int from String, also containing letters, in Java — J Richard Snape
– J Richard Snape, Commented Feb 2, 2015 at 12:35

roeygol · Accepted Answer · 2015-02-02 12:47:10Z

2

    final String NUM_OF_STUDENTS = "Number of Students: ";

    String numOfStudents = "Number of Students: 5";
    int lastIndex = numOfStudents.lastIndexOf(NUM_OF_STUDENTS);

    if (lastIndex != -1){
        String number = numOfStudents.substring((lastIndex + (NUM_OF_STUDENTS.length())) , numOfStudents.length());
        Integer yourResultNumber = Integer.parseInt(number);
        System.out.println(yourResultNumber);
    }

edited Feb 2, 2015 at 12:47

answered Feb 2, 2015 at 12:37

roeygol

5,07812 gold badges60 silver badges103 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

barq Over a year ago

Your code throws exceptions if String does not contain "Number of Students"

barq Over a year ago

After copying the fix from my answer and downvoting it.

roeygol Over a year ago

Well, your code did had an exception, I would thank you if you consider vote up my answer.

Sarz · Accepted Answer · 2015-02-02 12:41:55Z

1

Since Integer cannot parse String values it throws NumberFormatException because numbers are expected as input, I would suggest you as you have static type of Strings use like this:

String numOfStudents = "Number of Students: 5";
String[] p = numOfStudents.split(":");

Integer i= Integer.parseInt(p[1].trim());
System.out.println(i);

As, p[0] contain String (label) and p[1] contain its value. You can use it later if you want.

answered Feb 2, 2015 at 12:41

Sarz

1,9764 gold badges23 silver badges44 bronze badges

Comments

Paritosh · Accepted Answer · 2015-02-02 13:23:38Z

1

String numOfStudents = "Number of Students: 55546";
int lastIndex = numOfStudents.lastIndexOf(" ");
if(lastIndex > -1 && lastIndex+1 < numOfStudents.length()) {
String num = numOfStudents.substring(lastIndex+1);
System.out.println(Integer.parseInt(num));
}

edited Feb 2, 2015 at 13:23

Paritosh

5655 silver badges13 bronze badges

answered Feb 2, 2015 at 13:12

Nightswatch

1431 silver badge10 bronze badges

Collectives™ on Stack Overflow

How to parse an int from a string java?

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related