How to convert string to byte array using getBytes() function of String class in Java

Java How to use the getBytes() function of the String class to convert a string into a byte array

In Java, the String class stores strings in character form, and sometimes we need to convert strings into byte arrays. Convert it into a byte array for processing. At this time, you can use the getBytes() function of the String class to complete the conversion. The getByte() function encodes a string into a specified byte array and returns the byte array.

Below I will introduce how to use the getBytes() function in Java to convert a string into a byte array, and give relevant code examples.

Code example:

public class StringToByteArrayDemo {
    public static void main(String[] args) {
        String str = "Hello, World!";
        byte[] byteArray = str.getBytes();
        
        System.out.println("原始字符串：" + str);
        System.out.println("转换后的字节数组：" + Arrays.toString(byteArray));
    }
}

In the main() method in the above code, we first define a string variable str, whose value is "Hello, World!" . Next, we use the getBytes() function to convert the string into a byte array, and assign the converted byte array to the byteArray variable. Finally, print the original string and converted byte array via System.out.println().

Output result:

原始字符串：Hello, World!
转换后的字节数组：[72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33]

As can be seen from the output result, the original string "Hello, World!" is converted into a byte array [72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33].

It should be noted that the getBytes() function will use the platform's default character set to encode the string into a byte array by default. If you need to specify a character set, you can use the getBytes(String charsetName) function, where charsetName is the specified character set name. For example, the following code encodes a string into a byte array using the UTF-8 character set:

byte[] byteArray = str.getBytes("UTF-8");

In addition, the converted byte array is not necessarily the same length as the original string. This is because in Java, a character may occupy multiple bytes of storage space, especially when using non-ASCII character sets. If you need to get the length of a byte array, you can use byteArray.length.

To summarize, you can easily convert a string into a byte array through the getBytes() function of the String class. We can use this function to handle some situations that require operations in bytes, such as network transmission, encryption, file reading and writing, etc. At the same time, by specifying different character sets, we can also convert strings into different encoding methods.

I hope this article can help you understand how to use the getBytes() function in Java to convert a string into a byte array, as well as related application scenarios.

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