I have not been able to convert something like this:
byte[] b = new byte[] { 12, 24, 19, 17};
into something like this:
float myfloatvalue = ?;
Could someone please give me an example?
Also how to turn that float back to bytes?
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user1395152
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Are those bytes the bits of a float representation, or are they a 4-byte integer? – Bohemian Jan 13 '13 at 22:07
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And what order are they in? Is 12 the most significant or the least significant 8 bits? – Patricia Shanahan Jan 13 '13 at 22:08
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They are just random byte values that i typed out – user1395152 Jan 13 '13 at 22:16
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possible duplicate of [Java: Bytes to floats / ints](http://stackoverflow.com/questions/4513498/java-bytes-to-floats-ints) – Brian Roach Jan 13 '13 at 22:24
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The exact values don't matter. What do the bytes represent? In words, how do the bytes represent a float? – Code-Apprentice Jan 13 '13 at 23:44
3 Answers
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byte[] -> float
With ByteBuffer:
byte[] b = new byte[]{12, 24, 19, 17};
float f = ByteBuffer.wrap(b).getFloat();
float -> byte[]
Reverse operation (knowing the result of above):
float f = 1.1715392E-31f;
byte[] b = ByteBuffer.allocate(4).putFloat(f).array(); //[12, 24, 19, 17]
Tomasz Nurkiewicz
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3+1 honestly, ByteBuffer is an under-used, and under-appreciated class. – Bohemian Jan 13 '13 at 22:12
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@user1395152: please, read the documentation of `ByteBuffer`. And see my update. – Tomasz Nurkiewicz Jan 13 '13 at 22:16
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8+1 You may need to set the byte order with `.order(ByteBuffer.LITTE_ENDIAN)` as well. – Peter Lawrey Jan 13 '13 at 22:23
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This helped me a lot. Came handy when needed. Beauty is that it works even with `ByteBuffer` of Google's protobuf. Many many thanks! – Atul Dec 28 '16 at 16:01
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this should be: ByteBuffer.wrap(myBytes).order(ByteOrder.LITTLE_ENDIAN).getFloat(); – dotrinh PM Jul 12 '22 at 13:30
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From byte[] -> float, you could do:
byte[] b = new byte[] { 12, 24, 19, 17};
float myfloatvalue = ByteBuffer.wrap(b).getFloat();
Here is an alternative to using ByteBuffer.allocate for converting float -> byte[]:
int bits = Float.floatToIntBits(myFloat);
byte[] bytes = new byte[4];
bytes[0] = (byte)(bits & 0xff);
bytes[1] = (byte)((bits >> 8) & 0xff);
bytes[2] = (byte)((bits >> 16) & 0xff);
bytes[3] = (byte)((bits >> 24) & 0xff);
Reimeus
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3Minor point, ByeBuffer encodes in big endian and the current example is in little endian. Making them match would be great! Ty! – Sam Dec 16 '15 at 14:24
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Convert the bytes to an int and use Float.intBitsToFloat()
http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/Float.html#intBitsToFloat(int)
Chris
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