Byte Usage in String Encoding

Calculating the number of bytes in a string in Java requires consideration of the encoding method employed. Strings are sequences of characters, and the number of bytes required to represent them depends on the encoding scheme used to convert them into bytes.

Determining Byte Count

To get the size of a string in bytes, convert it into a byte array using the getBytes() method and inspect the array size:

String string = "Hello World";
byte[] utf8Bytes = string.getBytes("UTF-8");
int byteCount = utf8Bytes.length;

Encoding Considerations

The encoding scheme affects the byte count. Here are examples of different encodings applied to the same string:

byte[] utf8Bytes = string.getBytes("UTF-8");  // Each char as 1 byte
byte[] utf16Bytes = string.getBytes("UTF-16"); // Each char as 2 bytes
byte[] utf32Bytes = string.getBytes("UTF-32"); // Each char as 4 bytes
byte[] isoBytes = string.getBytes("ISO-8859-1");  // Each ASCII char as 1 byte
byte[] winBytes = string.getBytes("CP1252");   // Each ASCII char as 1 byte

Special Characters and Multi-Byte Encodings

Even ASCII strings can have varying byte counts depending on the encoding. For example, in UTF-8, some characters may require multiple bytes:

String interesting = "\uF93D\uF936\uF949\uF942"; // Chinese ideograms
byte[] utf8Bytes = interesting.getBytes("UTF-8");  // Each char as 3 bytes

Default Encoding and Explicit Specification

If no encoding argument is provided, the platform's default character set is used. It's recommended to always explicitly specify the desired character set to avoid unexpected results.