Integer decode() vs. valueOf()

[lalit upadheyay]

Hi,

Can someone clarify me the actual purpose and difference between two different functions for similar result in java.lang.Integer class. Their signatures are:

static Integer decode(String nm)
static Integer valueOf(String s)

Pls. also specify me whether i can pass an octal number as string to any of these methods and get back the hexadecimal number in a single step?

[John Dell'Oso]

Lalit,

The difference between these two methods is that with the decode() method you can pass octal and hexadecimal strings in addition to decimal strings. The single parameter version of the valueOf() method only interprets strings representing signed decimal integers.

For the decode() method, you pass radix specifiers such as "0x" or "#" for hex strings and "0" for octal strings.

The two parameter version of the valueOf() method is more flexible in that it can interpret strings represented in many different bases (up to base 36 I think).

Look at the following example:

public class IntegersMethodTest {
public static void main(String[] args) {
// decode decimal string (base 10)
Integer i = Integer.decode("1234");
System.out.println("The value of i is = " + i); // output = 1234
// decode octal string (base 8)
i = Integer.decode("01234");
System.out.println("The value of i is = " + i); // output = 668
// decode hexadecimal string (base 8)
i = Integer.decode("0x1234");
System.out.println("The value of i is = " + i); // output = 4660
// interpret string as decimal (base 10)
i = Integer.valueOf("1234");
System.out.println("The value of i is = " + i); // output = 1234
// interpret string as octal (base 8)
i = Integer.valueOf("1234", 8);
System.out.println("The value of i is = " + i); // output = 668
// interpret string as hexadecimal (base 16)
i = Integer.valueOf("1234", 16);
System.out.println("The value of i is = " + i); // output = 4660
}
}

Lalit, as much as I am happy to help you out here, the brief information I supplied above is all available from the Java API javadocs. You really should learn to use the javadocs for the API - it's a skill that will you serve you well.

Regards,
JD
[ July 04, 2005: Message edited by: John Dell'Oso ]

[lalit upadheyay]

Thanks John Dell'Oso for the nice reply. After you suggestion i have found way to convert an octal number to hexadecimal number in a single step precisely. It can be done as:

//decimal 1234=octal 2322=hexadecimal 4D2
System.out.println("The value of i is = " + Integer.toHexString(Integer.decode("02322").intValue())); // output = 4d2