Create a byte array according to given String In Java

Question

I just need to create a byte array out of the given String.

For example, if my String is String ss = "21331UA"; then the byte array elements should correspond to them as follows.

2 1 3 3 1 U A

I could have created it statically as this. byte[] arr = new byte[]{2,1,3,3,1,'U','A'} But have to create this byte array in the runtime dyanamically as this changes time to time. Thats the problem.

I just tried as follows and print them, it contains their corresponding ASCII values.This is not what I want.

byte[] arr = ss.getBytes();

for(int i=0; i<arr.length; i++)
{
    System.out.print(arr[i] + "  ");
}
Ans==> 50  49  51  51  49  85  65

Really appreciate any guidance.... Thanks in advance

byte is a numeric type in java, do you mean char '2', '1', '3' ...? — mana
– mana, Commented Jun 20, 2012 at 15:53
Hi Mana, I just need to dyanamically create this byte array to proceed to next step. Thats the problem. Otherwise I could have created it with this syntax... byte[] arr = new byte[]{2,1,3,3,1,'U','A'}. Thats why I am looking to create this array dyanamically in the run time and to use it in my application. Thanks... — JibW
– JibW, Commented Jun 20, 2012 at 16:10
@JibW If you were to print out the byte[] the way you create it, you'll get the exact same ASCII (which are the byte values) of that array. Calling getBytes() is the correct dynamic way of getting those values. — Poindexter
– Poindexter, Commented Jun 20, 2012 at 16:14
Hi Poindexter, My requirement is to create the byte array and to use it in the application. Since when I created with the getBytes() way it didn't work properly, I printed them and check what's going wrong there. My requirement is to create the byte array... Thanks — JibW
– JibW, Commented Jun 20, 2012 at 16:23
Ya, but like I said earlier, byte is numeric. It can only hold numbers from -128 to 127. It can not hold an 'U' but the byte representation for 'U' wich is 85. The ss.getBytes(); call is absolutely correct and does the right thing: Get the Byte representation of your String! — mana
– mana, Commented Jun 20, 2012 at 16:27

Daniel Bidulock · Accepted Answer · 2012-06-20 15:58:14Z

6

You could cast the values in your byte array like this:

System.out.print((char)arr[i] + "  ");

Or, alternatively, set your byte array to chars right off the bat:

char[] arr = ss.toCharArray();

for(int i=0; i<arr.length; i++)
{
    System.out.print(arr[i] + "  ");
}

edited Jun 20, 2012 at 15:58

answered Jun 20, 2012 at 15:53

Daniel Bidulock

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5 Comments

JibW Over a year ago

Hi Daniel, Yes When I print like this it prints what I want. I just need to create the byte array which exactly containing the characters of the String. Not ASCII Values...Because I just need a byte array that contains the exact characters I suggest by the string. Thanks

cklab Over a year ago

@JibW your code ss.getBytes() does exactly that, it is the byte[] representation of your String.

JibW Over a year ago

Hi cklab, Ya Thats the problem. I just need a way to create a byte array of the characters of the String...

JibW Over a year ago

Hi Daniel, I just need to dyanamically create this byte array to proceed to next step. Thats the problem. Otherwise I could have created it with this syntax... byte[] arr = new byte[]{2,1,3,3,1,'U','A'}. Thats why I am looking to create this array dyanamically in the run time and to use it in my application. A char array is not going to work for my scenario. Thanks.

Daniel Bidulock Over a year ago

@JibW, a byte array and a char array are essentially the same thing in that they are storing the exact same data. What you hope to pull back from these arrays is a matter of interpretation. If you want to store the string's individual characters in a byte array, you must cast the values you index as chars, otherwise you will see numeric data when you print to screen.

Fahim Parkar · Accepted Answer · 2012-06-20 15:57:06Z

0

You need to CAST byte to char as type of array arr[i] is byte.

Simply say

System.out.print((char) arr[i] + "  ");

answered Jun 20, 2012 at 15:57

Fahim Parkar

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1 Comment

JibW Over a year ago

Hi Fahim, When printing of course I can cast it like this. But I am looking for a way to create a byte array with the exact characters that the string contains.

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