How do you extract a String from a read-only ByteBuffer? I can't use the ByteBuffer.array() method because it throws a ReadOnlyException. Do I have to use ByteBuffer.get(arr[]) and copy it out to read the data and create a String? Seems wasteful to have to create a copy just to read it.
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2 Answers
You should be able to use Charset.decode(ByteBuffer) which will convert a ByteBuffer to a CharBuffer. Then just call toString() on that. Sample code:
import java.nio.*;
import java.nio.charset.*;
class Test {
public static void main(String[] args) throws Exception {
byte[] bytes = { 65, 66 }; // "AB" in ASCII
ByteBuffer byteBuffer =
ByteBuffer.wrap(bytes).asReadOnlyBuffer();
CharBuffer charBuffer = StandardCharsets.US_ASCII.decode(byteBuffer);
String text = charBuffer.toString();
System.out.println(text); // AB
}
}
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The ReadOnly buffer can't give you access tot he array, otherwise you might change it. Note: the String has yet another copy as a char[]. If this is a concern I would re-think the use of a read only buffer.
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