将 CharBuffer 转换为 ByteBuffer

Question

It is easy to convert a ByteBuffer to CharBuffer using ByteBuffer.asCharBuffer() .

How do I go in the other direction? Is there a simpler way than ByteBuffer Charset.encode(CharBuffer cb) ?

CharBuffer stores its data in an internal char[] and not byte[] therefore there is no underlying byte[] so there should be no simpler way.

Answer 1

Here's a suggestion.

    CharBuffer yourCharBuffer = CharBuffer.wrap("Roland");

    ByteBuffer result = ByteBuffer.allocate(yourCharBuffer.length() * Character.BYTES);
    CharBuffer converter = result.asCharBuffer();
    converter.append(yourCharBuffer);

    System.out.println(Arrays.toString(result.array()));

The above snippet prints:

[0, 82, 0, 111, 0, 108, 0, 97, 0, 110, 0, 100]

I am getting the byte array out that is simultaniously backing the converter CharArray and the result ByteArray . It's as close as I can get to your requirements. I may be missing something.

Edit: following the suggestion by @Marcono1234 in the comment I am using ByteBuffer.allocate(yourCharBuffer.length() * Character.BYTES) to allocate a correctly sized buffer.

If the code that filled your original CharBuffer could instead fill you byte buffer backed CharBuffer , it could be a bit simpler.

And you own suggestion, Charset.encode(CharBuffer) , is simpler still.