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<TITLE>Converting Between a BitSet and a Byte Array
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<h3>
e364.
Converting Between a BitSet and a Byte Array</h3>
There are no default methods for converting a <code>BitSet</code> to and from
a byte array. This example implements two methods to do the
conversion. These methods make it possible to easily work with both
<code>BitSet</code> and <code>BigInteger</code> and take advantage of their
capabilities when needed.
<pre>
// Returns a bitset containing the values in bytes.
// The byte-ordering of bytes must be big-endian which means the most significant bit is in element 0.
public static BitSet fromByteArray(byte[] bytes) {
BitSet bits = new BitSet();
for (int i=0; i<bytes.length*8; i++) {
if ((bytes[bytes.length-i/8-1]&(1<<(i%8))) > 0) {
bits.set(i);
}
}
return bits;
}
// Returns a byte array of at least length 1.
// The most significant bit in the result is guaranteed not to be a 1
// (since BitSet does not support sign extension).
// The byte-ordering of the result is big-endian which means the most significant bit is in element 0.
// The bit at index 0 of the bit set is assumed to be the least significant bit.
public static byte[] toByteArray(BitSet bits) {
byte[] bytes = new byte[bits.length()/8+1];
for (int i=0; i<bits.length(); i++) {
if (bits.get(i)) {
bytes[bytes.length-i/8-1] |= 1<<(i%8);
}
}
return bytes;
}
</pre>
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Related Examples
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e363. <a class="eglink" href="Bits.html?l=rel">
Performing Bitwise Operations on a Bit Vector
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See also:
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Arrays">
Arrays
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Collections">
Collections
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Dates">
Dates
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Hash%20Tables">
Hash Tables
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Lists">
Lists
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Property%20Files">
Property Files
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Sets">
Sets
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Sorted%20Collections">
Sorted Collections
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Time">
Time
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Timers">
Timers
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