Java 如何将字节数组转换为双精度并返回？

Question

为了将字节数组转换为双精度型，我发现了这一点：

//convert 8 byte array to double
int start=0;//???
int i = 0;
    int len = 8;
    int cnt = 0;
    byte[] tmp = new byte[len];
    for (i = start; i < (start + len); i++) {
        tmp[cnt] = arr[i];
        //System.out.println(java.lang.Byte.toString(arr[i]) + " " + i);
        cnt++;
    }
    long accum = 0;
    i = 0;
    for ( int shiftBy = 0; shiftBy < 64; shiftBy += 8 ) {
        accum |= ( (long)( tmp[i] & 0xff ) ) << shiftBy;
        i++;
    }

        return Double.longBitsToDouble(accum);

但是我找不到将双精度型转换为字节数组的任何东西。

Answer 1

甚至更简单

import java.nio.ByteBuffer;

public static byte[] toByteArray(double value) {
    byte[] bytes = new byte[8];
    ByteBuffer.wrap(bytes).putDouble(value);
    return bytes;
}

public static double toDouble(byte[] bytes) {
    return ByteBuffer.wrap(bytes).getDouble();
}