I have a String array. I want to convert it to byte array. I use the Java program. For example:
String str[] = {"aa", "55"};
convert to:
byte new[] = {(byte)0xaa, (byte)0x55};
What can I do?
10 Answers
String str = "Your string";
byte[] array = str.getBytes();
2 Comments
Tiny
Always specify a specific character set like
UTF-8 unless the default platform dependent character set is adequate (which is undesirable in most cases) using one of the overloaded versions of that method such as String#getBytes(Charset charset) or String#getBytes(String charsetName).
daddygames
byte[] array = str.getBytes("UTF-8"); throws UnsupportedEncodingException
Looking at the sample I guess you mean that a string array is actually an array of HEX representation of bytes, don't you?
If yes, then for each string item I would do the following:
- check that a string consists only of 2 characters
- these chars are in '0'..'9' or 'a'..'f' interval (take their case into account as well)
- convert each character to a corresponding number, subtracting code value of '0' or 'a'
build a byte value, where first char is higher bits and second char is lower ones. E.g.
int byteVal = (firstCharNumber << 4) | secondCharNumber;
Comments
Convert string to Byte-Array:
byte[] theByteArray = stringToConvert.getBytes();
Convert String to Byte:
String str = "aa";
byte b = Byte.valueOf(str);
1 Comment
Muhammed Refaat
it gives me
NumberFormatException when enter a value from A to FYou can try something similar to this :
String s = "65";
byte value = Byte.valueOf(s);
Use the Byte.ValueOf() method for all the elements in the String array to convert them into Byte values.
2 Comments
brian
It does not works. java.lang.NumberFormatException: unable to parse 'aa' as integer
Mithun Sasidharan
That means it was an empty string
A long way to go :). I am not aware of methods to get rid of long for statements
ArrayList<Byte> bList = new ArrayList<Byte>();
for(String ss : str) {
byte[] bArr = ss.getBytes();
for(Byte b : bArr) {
bList.add(b);
}
}
//if you still need an array
byte[] bArr = new byte[bList.size()];
for(int i=0; i<bList.size(); i++) {
bArr[i] = bList.get(i);
}
Comments
Since there was no answer for hex string to single byte conversion, here is mine:
private static byte hexStringToByte(String data) {
return (byte) ((Character.digit(data.charAt(0), 16) << 4)
| Character.digit(data.charAt(1), 16));
}
Sample usage:
hexStringToByte("aa"); // 170
hexStringToByte("ff"); // 255
hexStringToByte("10"); // 16
Or you can also try the Integer.parseInt(String number, int radix) imo, is way better than others.
// first parameter is a number represented in string
// second is the radix or the base number system to be use
Integer.parseInt("de", 16); // 222
Integer.parseInt("ad", 16); // 173
Integer.parseInt("c9", 16); // 201
1 Comment
nani
This is the best method for me
String source = "testString";
byte[] byteArray = source.getBytes(encoding);
You can foreach and do the same with all the strings in the array.
1 Comment
brian
My mean is change (String)"aa" to (byte)0xaa, but not to (byte)0x97, (byte)0x97
The simplest way (using Apache Common Codec):
byte[] bytes = Hex.decodeHex(str.toCharArray());
Comments
String str[] = {"aa", "55"};
byte b[] = new byte[str.length];
for (int i = 0; i < str.length; i++) {
b[i] = (byte) Integer.parseInt(str[i], 16);
}
Integer.parseInt(string, radix) converts a string into an integer, the radix paramter specifies the numeral system.
Use a radix of 16 if the string represents a hexadecimal number.
Use a radix of 2 if the string represents a binary number.
Use a radix of 10 (or omit the radix paramter) if the string represents a decimal number.
For further details check the Java docs: https://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#parseInt(java.lang.String,%20int)
1 Comment
Alex Huszagh
Code-only answers don't explain why the code works: please add an explanation for future visitors what you did to solve the problem.
Here, if you are converting string into byte[].There is a utility code :
String[] str = result.replaceAll("\\[", "").replaceAll("\\]","").split(", ");
byte[] dataCopy = new byte[str.length] ;
int i=0;
for(String s:str ) {
dataCopy[i]=Byte.valueOf(s);
i++;
}
return dataCopy;
byte n[] = str.getBytes()will do the task. However, you'll get error onnewas it is a keyword and cannot be used as identifier.{97, 97}and{53, 53}?