In Java, we can use new String(bytes, StandardCharsets.UTF_8) to convert a byte[] to a String.
// string to byte[]
byte[] bytes = "hello".getBytes(StandardCharsets.UTF_8);
// byte[] to string
String s = new String(bytes, StandardCharsets.UTF_8);
Table of contents
- 1. byte[] in text and binary data
- 2. Convert byte[] to String (text data)
- 3. Convert byte[] to String (binary data)
- 4. Download Source Code
- 5. References
1. byte[] in text and binary data
For text or character data, we use new String(bytes, StandardCharsets.UTF_8) to convert the byte[] to a String directly. However, for cases that byte[] is holding the binary data like the image or other non-text data, the best practice is to convert the byte[] into a Base64 encoded string.
// convert file to byte[]
byte[] bytes = Files.readAllBytes(Paths.get("/path/image.png"));
// Java 8 - Base64 class, finally.
// encode, convert byte[] to base64 encoded string
String s = Base64.getEncoder().encodeToString(bytes);
System.out.println(s);
// decode, convert base64 encoded string back to byte[]
byte[] decode = Base64.getDecoder().decode(s);
// This Base64 encode decode string is still widely use in
// 1. email attachment
// 2. embed image files inside HTML or CSS
Note
- For
text data byte[], trynew String(bytes, StandardCharsets.UTF_8). - For
binary data byte[], try Base64 encoding.
2. Convert byte[] to String (text data)
The below example convert a string to a byte array or byte[] and vice versa.
Warning
The common mistake is trying to use the bytes.toString() to get the string from the bytes; The bytes.toString() only returns the address of the object in memory, NOT converting byte[] to a string! The correct way to convert byte[] to string is new String(bytes, StandardCharsets.UTF_8).
package com.mkyong.string;
import java.nio.charset.StandardCharsets;
public class ConvertBytesToString2 {
public static void main(String[] args) {
String str = "This is raw text!";
// string to byte[]
byte[] bytes = str.getBytes(StandardCharsets.UTF_8);
System.out.println("Text : " + str);
System.out.println("Text [Byte Format] : " + bytes);
// no, don't do this, it returns the address of the object in memory
System.out.println("Text [Byte Format] toString() : " + bytes.toString());
// convert byte[] to string
String s = new String(bytes, StandardCharsets.UTF_8);
System.out.println("Output : " + s);
// old code, UnsupportedEncodingException
// String s1 = new String(bytes, "UTF_8");
}
}
Output
Text : This is raw text!
Text [Byte Format] : [B@372f7a8d
Text [Byte Format] toString() : [B@372f7a8d
Output : This is raw text!
3. Convert byte[] to String (binary data)
The below example converts an image phone.png into a byte[], and uses the Java 8 Base64 class to convert the byte[] to a Base64 encoded String.
Later, we convert the Base64 encoded string back to the original byte[] and save it into another image named phone2.png.
package com.mkyong.string;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Base64;
public class ConvertBytesToStringBase64 {
public static void main(String[] args) {
String filepath = "/Users/mkyong/phone.png";
Path path = Paths.get(filepath);
if (Files.notExists(path)) {
throw new IllegalArgumentException("File is not exists!");
}
try {
// convert the file's content to byte[]
byte[] bytes = Files.readAllBytes(path);
// encode, byte[] to Base64 encoded string
String s = Base64.getEncoder().encodeToString(bytes);
System.out.println(s);
// decode, Base64 encoded string to byte[]
byte[] decode = Base64.getDecoder().decode(s);
// save into another image file.
Files.write(Paths.get("/Users/mkyong/phone2.png"), decode);
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output
bh5aLyZALN4othXL2mByHo1aZA5ts5k/uw/sc7DBngGY......
# if everything ok, it save the byte[] into a new image phone2.png
4. Download Source Code
$ git clone https://github.com/mkyong/core-java
$ cd java-string
this worked for me thanks a lot. i used it to decode parquet data and then write that data to parquet file. worked
Could you please help to show converting a string to a Java object ?
Why do you specify the encoding UTF-8 when converting from bytes to string, but not string to bytes? I think when you call the “getBytes” method you should also pass StandardCharsets.UTF_8, otherwise you will get a result using the platform default encoding, which may be UTF-16. When you convert back to a string, and specify the encoding of UTF-8 specifically, it won’t work if that was a UTF-16 string with supplementary characters.
Article is updated, thanks for your feedback.
Thanks for the information. Could you also please let me know how to convert Byte[] (capital B) to String. The above code does not work for the nonprimitive Byte[]. Thank you.
Regards,
Amar
Byte is a class, its not a datatype. Whereas byte[] array is a datatype. It will be more clear from the code snippet below:
//—————————————————————————————————————————-//
public static void main (String[] args){
byte b = 18;
Byte wrappedByte = new Byte(b);
}
//—————————————————————————————————————————-//
Byte[] and byte[] are incompatible (you can google “boxed primitive arrays” for more info). You probably need to explicitly convert, like
//assume you have a value Byte[] bytes
byte[] primitiveArray = new byte[bytes.length];
for (int i = 0; i < bytes.length; i++) {
primitiveArray[i] = bytes[i].byteValue();
}
String s = new String(primitiveArray, StandardCharsets.UTF_8);
//…etc
please tell me a program source code in java that convert text to binary and binary to text.
If you want to find the binary of a singular alphabet, then you can make use of Ascii codes as given below:
//—————————————————————————————————————————//
public class TexttoBinary {
public static void main (String[] args){
char ch=’A’;
System.out.println((int)ch); // prints ASCII of ‘A’
String text = Integer.toBinaryString(ch); // converts ASCII value to Binary
System.out.println(text);
}
}
//————————————————————————————————————————-//
If you wish to convert text strings to binary then you can use the below mentioned code:
//————————————————————————————————————————-//
import java.math.BigInteger;
import java.nio.charset.Charset;
public class TexttoBinary {
public static void main (String[] args){
String str = “Java”;
String hex = toHex(str); // converts String to hexadecimal format
String binary = hexToBinary(hex); // converts Hexadecimal string to binary format
System.out.println(binary);
}
public static String toHex(String arg) {
return String.format(“%040x”, new BigInteger(1, arg.getBytes(Charset.defaultCharset())));
}
static String hexToBinary(String s) {
return new BigInteger(s, 16).toString(2);
}
}
For binary data, we need Base64 encoder, see above example 2.
Thank you
Thanks sir! Saved me several hours. You are awesome!
Thanks man. That helped.
I am trying to convert bytes into String. I am reading the image data and storing into byte array. then i think bytes length is so much. Is there any limit for bytes length? Will there be anyloss of data when converting bytes into string.
We can use Base64 for binary-to-text encoding.
Thanks for sharing
Thank you 🙂
Thanks, for sharing such simple codes. it helps!
The issue I find with this byte string conversion is starting from byte{], convert it to String, then retrieve the original byte{} again!
The most stable solution I found so far is using sun.misc.BASE64Encoder().encode(myByte) and sun.misc.BASE64Decoder().decodeBuffer(myString) but with a java sun warning!
Any one with a better solution?
Try the new Java 8
java.util.Base64This helped and saved time for a newbie like me 🙂
oh, thanks a lot. this simple code help me very much.
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