[Caliraj]

Hi,
I was going through the wrapper classes aspect in Java, where I had come across the utility methods llike valueOf(),toString etc.I have the follwing program :
class Wrappers
{
public static void main(String args[])
{
int j=10;
String str=Integer.toString(j);
System.out.println("The string value of the Integer is "+str);
String st="Hello";
Integer x=String.valueOf(st);
System.out.println("The Integer value of the string is "+x);
}
}

Firstly, Im trying to convert integer 10 to a string.But the output shows 10 only.Secondly, Im tryong to cnvert "Hello" to integer for which Im getting an error that says as below:
Wrappers.java:12: incompatible types
found : java.lang.String
required: java.lang.Integer
Integer x=String.valueOf(st);
^

Im totally lost Could anyone explain how these functions work?

[Chicon]

How to convert a string into an integer in Java

Here's the formula :

String test = "12345";
int value = Integer.parseInt(test);

In your example, you try to convert a string that contains no numeric data ("Hello").
If you apply my above formula, you'll get a NumberFormatException.
When you're not sure of a string content to convert into an integer, it is advised to apply the following code :

String test = "Hello";
int value;
try {
    value = Integer.parseInt(test);
    System.out.println("The value returned is " + value); 
} catch(NumberFormatException nfe) {
    System.out.println("<" + test + "> is not numeric");
}

[Caliraj]

Hi Chicon,
Thanks for the answers...could you suggest a website that explains everything clearly regarding wrapper classes & the utility methods?

[Chicon]

Here is a good explanation.

To have a more complete description of the attributes and methods of classes, it is better to browse the site of the Java creators : example, here is the description of the wrapper class Integer.