converting string to integer

[Ann-Marie Russell]

I am new to Java, coming from VB.NET. In VB it is rather simple to convert from any single datatype to another by doing a ctype(). I am trying to convert a string to an integer using java. I know that i can conver types such as a float to an integer using: int blah = (int) float but i receive an error when trying to do this to a string...any words of advice are welcome.

thanks,
AMR

[David Ulicny]

int i = Integer.parseInt("1");
int j = new Integer("1").intValue();

[Ernest Friedman-Hill]

Hi Ann-Marie,

Welcome to JavaRanch!

The static method java.lang.Integer.parseInt() is one way to do this:

  String s = "35";
  int i = Integer.parseInt(s);

Likewise, there's a parseDouble() in java.lang.Double, a parseFloat() in java.lang.Float(), etc. These methods report failure -- i.e., a String that doesn't look like a valid number -- by throwing NumberFormatException; a proper program has to catch and deal with that error.

[Ramaswamy Srinivasan]

Hi Ann-Marie,

I agree with this way of converting types suggested by Ernst.

String s = "35"; int i = Integer.parseInt(s);

And thanks Ernst for the insight into other parseXXXX() methods.

I came across a good deal of information on Casting and datatypes in the book Head First Java - by Kathy Sierra & Bert Bates.
You can get a good start, especially if u r starting with Java.

Cheers,
Swamy

[Chengwei Lee]

Don't forget to put your codes in a try-catch block, you never know when the string argument that you're receiving could turn out to be unparsable.

[Ramaswamy Srinivasan]

Hi Cheng...

string argument that you're receiving could turn out to be unparsable

Thanks for pointing that out. If you don't mind, can u give some elaboration on the Unparsable Strings. Like some instances where this can happen?

Cheers,
Swamy

[Jeff Bosch]

 
 
String s = "Bob-GoBobaLooie";
int i = Integer.parseInt(s); // Ouch! Error, Will Robinson!
 

[Nigel Browne]

or maybe

int i = new Integer("This wont work").intValue();

[Mark Vedder]

Originally posted by Ramaswamy Srinivasan:
If you don't mind, can u give some elaboration on the Unparsable Strings. Like some instances where this can happen?

Originally posted by Jeff Bosch:

String s = "Bob-GoBobaLooie";
int i = Integer.parseInt(s); // Ouch! Error, Will Robinson!
 

Or the equally as bad, but maybe less obvious:

String s = "3.1415";
int i;
try
{
    i = Integer.parseInt(s);
}
catch (NumberFormatException nfe)
{
    //handle exception here
}

The following would work (i.e. not throw an exception)...

String s = "3.1415";
double d;
try
{
    d = Double.parseDouble(s);
}
catch (NumberFormatException nfe)
{
    //handle exception here
}

[Ramaswamy Srinivasan]

Hi all,

Thanks a lot guys, for making the thing clear..

Cheers,
Swamy