Solved

Byte Array to Integer

Posted on 1998-04-12
3
524 Views
Last Modified: 2009-07-29
I have a byte[] array of size 4 which I want to convert into a 4-byte int or Integer. What method should I use to do this?

I have tried:
String key = new String(bArray, 0, 3);
int result = Integer.valueOf(key).intValue();

which does not seem to work.

Any help would be appreciated.
0
Comment
Question by:iwt
3 Comments
 
LVL 1

Expert Comment

by:peter_vc
ID: 1234052
I think you can just cast it to an Integer:

String key = new String(bArray,0,3);
int result = int(key);

I don't have my Java stuff installed on this machine so I can't test it.

0
 

Author Comment

by:iwt
ID: 1234053
No answer needed; I found a solution using the code from RandomAccessFile.java's WriteInt() and reversing it, which bypasses the need for a String.

For others' use, I've posted it below:

int result = ((bArray[0] << 24) | (bArray[1] << 16) + (bArray[2] << 8) + bArray[3]);

0
 
LVL 2

Accepted Solution

by:
anguslai earned 70 total points
ID: 1234054
Convert a byte array of 4 into 32 bits integer :

Assume :
     byte array named byteArray
     byte[0] contained the left most  8 bits (bit 25 to bit 32);
     
then use the following code to convert byteArray to int:
    int A = byteArray[0]<<24 | byteArray[1]<<16 | byteArray[2]<<8 | byteArray[3];

Note: the left most bit in primitive type int is a sign bit. Therefore, don't forget to treat the left most bit in byte[0] as sign bit.
0

Featured Post

Master Your Team's Linux and Cloud Stack

Come see why top tech companies like Mailchimp and Media Temple use Linux Academy to build their employee training programs.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
ArrayIndexOutOfBoundException 9 83
web application structure 18 77
sql import cannot be resolved jsp 3 23
printf performancy 11 43
An old method to applying the Singleton pattern in your Java code is to check if a static instance, defined in the same class that needs to be instantiated once and only once, is null and then create a new instance; otherwise, the pre-existing insta…
Introduction This article is the first of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article explains our test automation goals. Then rationale is given for the tools we use to a…
Video by: Michael
Viewers learn about how to reduce the potential repetitiveness of coding in main by developing methods to perform specific tasks for their program. Additionally, objects are introduced for the purpose of learning how to call methods in Java. Define …
Viewers will learn one way to get user input in Java. Introduce the Scanner object: Declare the variable that stores the user input: An example prompting the user for input: Methods you need to invoke in order to properly get  user input:

810 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question