Java bitset from int

Java bitset from int

This class implements a vector of bits that grows as needed. Each component of the bit set has a boolean value. The bits of a BitSet are indexed by nonnegative integers. Individual indexed bits can be examined, set, or cleared. One BitSet may be used to modify the contents of another BitSet through logical AND, logical inclusive OR, and logical exclusive OR operations. By default, all bits in the set initially have the value false . Every bit set has a current size, which is the number of bits of space currently in use by the bit set. Note that the size is related to the implementation of a bit set, so it may change with implementation. The length of a bit set relates to logical length of a bit set and is defined independently of implementation. Unless otherwise noted, passing a null parameter to any of the methods in a BitSet will result in a NullPointerException . A BitSet is not safe for multithreaded use without external synchronization.

Constructor Summary

Creates a bit set whose initial size is large enough to explicitly represent bits with indices in the range 0 through nbits-1 .

Method Summary

Sets the bits from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to false .

Sets each bit from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to the complement of its current value.

Returns a new BitSet composed of bits from this BitSet from fromIndex (inclusive) to toIndex (exclusive).

Returns true if the specified BitSet has any bits set to true that are also set to true in this BitSet .

Returns the index of the first bit that is set to false that occurs on or after the specified starting index.

Returns the index of the first bit that is set to true that occurs on or after the specified starting index.

Returns the index of the nearest bit that is set to false that occurs on or before the specified starting index.

Returns the index of the nearest bit that is set to true that occurs on or before the specified starting index.

Sets the bits from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to true .

Sets the bits from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to the specified value.

Returns a new bit set containing all the bits in the given byte buffer between its position and limit.

Returns a new bit set containing all the bits in the given long buffer between its position and limit.

Methods declared in class java.lang.Object

Constructor Detail

BitSet

BitSet

Creates a bit set whose initial size is large enough to explicitly represent bits with indices in the range 0 through nbits-1 . All bits are initially false .

Method Detail

valueOf

Returns a new bit set containing all the bits in the given long array. More precisely,
BitSet.valueOf(longs).get(n) == ((longs[n/64] & (1L<<(n%64))) != 0)
for all n < 64 * longs.length . This method is equivalent to BitSet.valueOf(LongBuffer.wrap(longs)) .

valueOf

Returns a new bit set containing all the bits in the given long buffer between its position and limit. More precisely,
BitSet.valueOf(lb).get(n) == ((lb.get(lb.position()+n/64) & (1L<<(n%64))) != 0)
for all n < 64 * lb.remaining() . The long buffer is not modified by this method, and no reference to the buffer is retained by the bit set.

valueOf

Returns a new bit set containing all the bits in the given byte array. More precisely,
BitSet.valueOf(bytes).get(n) == ((bytes[n/8] & (1<<(n%8))) != 0)
for all n < 8 * bytes.length . This method is equivalent to BitSet.valueOf(ByteBuffer.wrap(bytes)) .

valueOf

Returns a new bit set containing all the bits in the given byte buffer between its position and limit. More precisely,
BitSet.valueOf(bb).get(n) == ((bb.get(bb.position()+n/8) & (1<<(n%8))) != 0)
for all n < 8 * bb.remaining() . The byte buffer is not modified by this method, and no reference to the buffer is retained by the bit set.

toByteArray

Returns a new byte array containing all the bits in this bit set. More precisely, if
byte[] bytes = s.toByteArray();
then bytes.length == (s.length()+7)/8 and
s.get(n) == ((bytes[n/8] & (1<<(n%8))) != 0)
for all n < 8 * bytes.length .

toLongArray

Returns a new long array containing all the bits in this bit set. More precisely, if
long[] longs = s.toLongArray();
then longs.length == (s.length()+63)/64 and
s.get(n) == ((longs[n/64] & (1L<<(n%64))) != 0)
for all n < 64 * longs.length .

flip

public void flip​(int bitIndex)

flip

public void flip​(int fromIndex, int toIndex)

Sets each bit from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to the complement of its current value.

set

public void set​(int bitIndex)

set

public void set​(int bitIndex, boolean value)

set

public void set​(int fromIndex, int toIndex)

Sets the bits from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to true .

set

public void set​(int fromIndex, int toIndex, boolean value)

Sets the bits from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to the specified value.

clear

public void clear​(int bitIndex)

clear

public void clear​(int fromIndex, int toIndex)

Sets the bits from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to false .

clear

get

public boolean get​(int bitIndex)

Returns the value of the bit with the specified index. The value is true if the bit with the index bitIndex is currently set in this BitSet ; otherwise, the result is false .

get

public BitSet get​(int fromIndex, int toIndex)

Returns a new BitSet composed of bits from this BitSet from fromIndex (inclusive) to toIndex (exclusive).

nextSetBit

public int nextSetBit​(int fromIndex)

Returns the index of the first bit that is set to true that occurs on or after the specified starting index. If no such bit exists then -1 is returned. To iterate over the true bits in a BitSet , use the following loop:

 for (int i = bs.nextSetBit(0); i >= 0; i = bs.nextSetBit(i+1)) < // operate on index i here if (i == Integer.MAX_VALUE) < break; // or (i+1) would overflow >>

nextClearBit

public int nextClearBit​(int fromIndex)

Returns the index of the first bit that is set to false that occurs on or after the specified starting index.

previousSetBit

public int previousSetBit​(int fromIndex)

Returns the index of the nearest bit that is set to true that occurs on or before the specified starting index. If no such bit exists, or if -1 is given as the starting index, then -1 is returned. To iterate over the true bits in a BitSet , use the following loop:

 for (int i = bs.length(); (i = bs.previousSetBit(i-1)) >= 0; ) < // operate on index i here >

previousClearBit

public int previousClearBit​(int fromIndex)

Returns the index of the nearest bit that is set to false that occurs on or before the specified starting index. If no such bit exists, or if -1 is given as the starting index, then -1 is returned.

length

Returns the «logical size» of this BitSet : the index of the highest set bit in the BitSet plus one. Returns zero if the BitSet contains no set bits.

isEmpty

intersects

Returns true if the specified BitSet has any bits set to true that are also set to true in this BitSet .

cardinality

and

Performs a logical AND of this target bit set with the argument bit set. This bit set is modified so that each bit in it has the value true if and only if it both initially had the value true and the corresponding bit in the bit set argument also had the value true .

or

Performs a logical OR of this bit set with the bit set argument. This bit set is modified so that a bit in it has the value true if and only if it either already had the value true or the corresponding bit in the bit set argument has the value true .

xor

• The bit initially has the value true , and the corresponding bit in the argument has the value false .
• The bit initially has the value false , and the corresponding bit in the argument has the value true .

andNot

hashCode

Returns the hash code value for this bit set. The hash code depends only on which bits are set within this BitSet . The hash code is defined to be the result of the following calculation:

 public int hashCode() < long h = 1234; long[] words = toLongArray(); for (int i = words.length; --i >= 0; ) h ^= words[i] * (i + 1); return (int)((h >> 32) ^ h); >

size

Returns the number of bits of space actually in use by this BitSet to represent bit values. The maximum element in the set is the size — 1st element.

equals

Compares this object against the specified object. The result is true if and only if the argument is not null and is a Bitset object that has exactly the same set of bits set to true as this bit set. That is, for every nonnegative int index k ,

clone

Cloning this BitSet produces a new BitSet that is equal to it. The clone of the bit set is another bit set that has exactly the same bits set to true as this bit set.

toString

Returns a string representation of this bit set. For every index for which this BitSet contains a bit in the set state, the decimal representation of that index is included in the result. Such indices are listed in order from lowest to highest, separated by «, » (a comma and a space) and surrounded by braces, resulting in the usual mathematical notation for a set of integers. Example:

BitSet drPepper = new BitSet();

drPepper.set(4); drPepper.set(10);

stream

Returns a stream of indices for which this BitSet contains a bit in the set state. The indices are returned in order, from lowest to highest. The size of the stream is the number of bits in the set state, equal to the value returned by the cardinality() method. The stream binds to this bit set when the terminal stream operation commences (specifically, the spliterator for the stream is late-binding). If the bit set is modified during that operation then the result is undefined.

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