OpenJDK 1.22 · java.util.BitSet · APIdia, the JavaDoc alternative

Modifier and Type	Field and Description
private static final int	ADDRESS_BITS_PER_WORD
private static final int	BIT_INDEX_MASK
private static final int	BITS_PER_WORD
private static final ObjectStreamField[]	serialPersistentFields
private static final long	serialVersionUID
private transient boolean	sizeIsSticky Whether the size of "words" is user-specified.
private static final long	WORD_MASK
private long[]	words The internal field corresponding to the serialField "bits".
private transient int	wordsInUse The number of words in the logical size of this BitSet.

Access	Constructor and Description
public	BitSet() Creates a new bit set.
public	BitSet(int the initial size of the bit set nbits) Creates a bit set whose initial size is large enough to explicitly represent bits with indices in the range `0` through `nbits-1`.
private	BitSet(long[] words) Creates a bit set using words as the internal representation.

Method Summary

Modifier and Type	Method and Description
public void	and(BitSet a bit set set) Performs a logical AND of this target bit set with the argument bit set.
public void	andNot(BitSet the `BitSet` with which to mask this `BitSet` set) Clears all of the bits in this `BitSet` whose corresponding bit is set in the specified `BitSet`.
public int	Returns: the number of bits set to `true` in this `BitSet` cardinality() Returns the number of bits set to `true` in this `BitSet`.
private void	checkInvariants() Every public method must preserve these invariants.
private static void	checkRange(int fromIndex, int toIndex) Checks that fromIndex ...
public void	clear(int the index of the bit to be cleared bitIndex) Sets the bit specified by the index to `false`.
public void	clear(int index of the first bit to be cleared fromIndex, int index after the last bit to be cleared toIndex) Sets the bits from the specified `fromIndex` (inclusive) to the specified `toIndex` (exclusive) to `false`.
public void	clear() Sets all of the bits in this BitSet to `false`.
public Object	Returns: a clone of this bit set clone() Overrides java.lang.Object.clone. Cloning this `BitSet` produces a new `BitSet` that is equal to it.
private void	ensureCapacity(int the minimum acceptable number of words. wordsRequired) Ensures that the BitSet can hold enough words.
public boolean	Returns: `true` if the objects are the same; `false` otherwise equals(Object the object to compare with obj) Overrides java.lang.Object.equals. Compares this bit set against the specified object.
private void	expandTo(int the index to be accommodated. wordIndex) Ensures that the BitSet can accommodate a given wordIndex, temporarily violating the invariants.
public void	flip(int the index of the bit to flip bitIndex) Sets the bit at the specified index to the complement of its current value.
public void	flip(int index of the first bit to flip fromIndex, int index after the last bit to flip toIndex) Sets each bit from the specified `fromIndex` (inclusive) to the specified `toIndex` (exclusive) to the complement of its current value.
public boolean	Returns: the value of the bit with the specified index get(int the bit index bitIndex) Returns the value of the bit with the specified index.
public BitSet	Returns: a new `BitSet` from a range of this `BitSet` get(int index of the first bit to include fromIndex, int index after the last bit to include toIndex) Returns a new `BitSet` composed of bits from this `BitSet` from `fromIndex` (inclusive) to `toIndex` (exclusive).
public int	Returns: the hash code value for this bit set hashCode() Overrides java.lang.Object.hashCode. Returns the hash code value for this bit set.
private void	initWords(int nbits)
public boolean	Returns: boolean indicating whether this `BitSet` intersects the specified `BitSet` intersects(BitSet `BitSet` to intersect with set) Returns true if the specified `BitSet` has any bits set to `true` that are also set to `true` in this `BitSet`.
public boolean	Returns: boolean indicating whether this `BitSet` is empty isEmpty() Returns true if this `BitSet` contains no bits that are set to `true`.
public int	Returns: the logical size of this `BitSet` length() Returns the "logical size" of this `BitSet`: the index of the highest set bit in the `BitSet` plus one.
public int	Returns: the index of the next clear bit nextClearBit(int the index to start checking from (inclusive) fromIndex) Returns the index of the first bit that is set to `false` that occurs on or after the specified starting index.
public int	Returns: the index of the next set bit, or `-1` if there is no such bit nextSetBit(int the index to start checking from (inclusive) fromIndex) Returns the index of the first bit that is set to `true` that occurs on or after the specified starting index.
private int	Returns: the index of the next set bit, or `-1` if there is no such bit nextSetBit(int the index to start checking from (inclusive) fromIndex, int the last word index to check (inclusive) toWordIndex) Returns the index of the first bit that is set to `true` that occurs on or after the specified starting index and up to and including the specified word index If no such bit exists then `-1` is returned.
public void	or(BitSet a bit set set) Performs a logical OR of this bit set with the bit set argument.
public int	Returns: the index of the previous clear bit, or `-1` if there is no such bit previousClearBit(int the index to start checking from (inclusive) fromIndex) Returns the index of the nearest bit that is set to `false` that occurs on or before the specified starting index.
public int	Returns: the index of the previous set bit, or `-1` if there is no such bit previousSetBit(int the index to start checking from (inclusive) fromIndex) Returns the index of the nearest bit that is set to `true` that occurs on or before the specified starting index.
private void	readObject(ObjectInputStream s) Reconstitute the `BitSet` instance from a stream (i.e., deserialize it).
private void	recalculateWordsInUse() Sets the field wordsInUse to the logical size in words of the bit set.
public void	set(int a bit index bitIndex) Sets the bit at the specified index to `true`.
public void	set(int a bit index bitIndex, boolean a boolean value to set value) Sets the bit at the specified index to the specified value.
public void	set(int index of the first bit to be set fromIndex, int index after the last bit to be set toIndex) Sets the bits from the specified `fromIndex` (inclusive) to the specified `toIndex` (exclusive) to `true`.
public void	set(int index of the first bit to be set fromIndex, int index after the last bit to be set toIndex, boolean value to set the selected bits to value) Sets the bits from the specified `fromIndex` (inclusive) to the specified `toIndex` (exclusive) to the specified value.
public int	Returns: the number of bits currently in this bit set size() Returns the number of bits of space actually in use by this `BitSet` to represent bit values.
public IntStream	Returns: a stream of integers representing set indices stream() Returns a stream of indices for which this `BitSet` contains a bit in the set state.
public byte[]	Returns: a byte array containing a little-endian representation of all the bits in this bit set toByteArray() Returns a new byte array containing all the bits in this bit set.
public long[]	Returns: a long array containing a little-endian representation of all the bits in this bit set toLongArray() Returns a new long array containing all the bits in this bit set.
public String	Returns: a string representation of this bit set toString() Overrides java.lang.Object.toString. Returns a string representation of this bit set.
private void	trimToSize() Attempts to reduce internal storage used for the bits in this bit set.
public static BitSet	Returns: a `BitSet` containing all the bits in the long array valueOf(long[] a long array containing a little-endian representation of a sequence of bits to be used as the initial bits of the new bit set longs) Returns a new bit set containing all the bits in the given long array.
public static BitSet	Returns: a `BitSet` containing all the bits in the buffer in the specified range valueOf(LongBuffer a long buffer containing a little-endian representation of a sequence of bits between its position and limit, to be used as the initial bits of the new bit set lb) Returns a new bit set containing all the bits in the given long buffer between its position and limit.
public static BitSet	Returns: a `BitSet` containing all the bits in the byte array valueOf(byte[] a byte array containing a little-endian representation of a sequence of bits to be used as the initial bits of the new bit set bytes) Returns a new bit set containing all the bits in the given byte array.
public static BitSet	Returns: a `BitSet` containing all the bits in the buffer in the specified range valueOf(ByteBuffer a byte buffer containing a little-endian representation of a sequence of bits between its position and limit, to be used as the initial bits of the new bit set bb) Returns a new bit set containing all the bits in the given byte buffer between its position and limit.
private static int	wordIndex(int bitIndex) Given a bit index, return word index containing it.
private void	writeObject(ObjectOutputStream s) Save the state of the `BitSet` instance to a stream (i.e., serialize it).
public void	xor(BitSet a bit set set) Performs a logical XOR of this bit set with the bit set argument.

Inherited from java.lang.Object:: finalize getClass notify notifyAll wait wait wait

ADDRESS_BITS_PER_WORD	back to summary
private static final int ADDRESS_BITS_PER_WORD

BIT_INDEX_MASK	back to summary
private static final int BIT_INDEX_MASK

BITS_PER_WORD	back to summary
private static final int BITS_PER_WORD

serialPersistentFields	back to summary
private static final ObjectStreamField[] serialPersistentFields Annotations @Serial Serial Fields: bits:long[] The bits in this BitSet. The ith bit is stored in bits[i/64] at bit position i % 64 (where bit position 0 refers to the least significant bit and 63 refers to the most significant bit).

serialVersionUID	back to summary
private static final long serialVersionUID Annotations @Serial

sizeIsSticky	back to summary
private transient boolean sizeIsSticky Whether the size of "words" is user-specified. If so, we assume the user knows what he's doing and try harder to preserve it.

WORD_MASK	back to summary
private static final long WORD_MASK

words	back to summary
private long[] words The internal field corresponding to the serialField "bits".

wordsInUse	back to summary
private transient int wordsInUse The number of words in the logical size of this BitSet.

BitSet	back to summary
public BitSet() Creates a new bit set. All bits are initially `false`.

BitSet	back to summary
public BitSet(int nbits) 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`. Parameters nbits:int the initial size of the bit set Exceptions NegativeArraySizeException: if the specified initial size is negative

BitSet	back to summary
private BitSet(long[] words) Creates a bit set using words as the internal representation. The last word (if there is one) must be non-zero.

Method Detail

and back to summary

and	back to summary
public void and(BitSet set) 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`. Parameters set:BitSet a bit set

public void and(BitSet set)

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.

Parameters

set:BitSet: a bit set

andNot back to summary

andNot	back to summary
public void andNot(BitSet set) Clears all of the bits in this `BitSet` whose corresponding bit is set in the specified `BitSet`. Parameters set:BitSet the `BitSet` with which to mask this `BitSet` Since 1.2

public void andNot(BitSet set)

Clears all of the bits in this BitSet whose corresponding bit is set in the specified BitSet.

Parameters

set:BitSet: the BitSet with which to mask this BitSet

Since

1.2

cardinality back to summary

cardinality	back to summary
public int cardinality() Returns the number of bits set to `true` in this `BitSet`. Returns:int the number of bits set to `true` in this `BitSet` Since 1.4

public int cardinality()

Returns the number of bits set to true in this BitSet.

Returns:int: the number of bits set to true in this BitSet
Since: 1.4

checkInvariants	back to summary
private void checkInvariants() Every public method must preserve these invariants.

checkRange	back to summary
private static void checkRange(int fromIndex, int toIndex) Checks that fromIndex ... toIndex is a valid range of bit indices.

clear back to summary

clear	back to summary
public void clear(int bitIndex) Sets the bit specified by the index to `false`. Parameters bitIndex:int the index of the bit to be cleared Exceptions IndexOutOfBoundsException: if the specified index is negative Since 1.0

public void clear(int bitIndex)

Sets the bit specified by the index to false.

Parameters

bitIndex:int: the index of the bit to be cleared

Exceptions

IndexOutOfBoundsException:: if the specified index is negative

Since

1.0

clear back to summary

clear	back to summary
public void clear(int fromIndex, int toIndex) Sets the bits from the specified `fromIndex` (inclusive) to the specified `toIndex` (exclusive) to `false`. Parameters fromIndex:int index of the first bit to be cleared toIndex:int index after the last bit to be cleared Exceptions IndexOutOfBoundsException: if `fromIndex` is negative, or `toIndex` is negative, or `fromIndex` is larger than `toIndex` Since 1.4

public void clear(int fromIndex, int toIndex)

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

Parameters

fromIndex:int: index of the first bit to be cleared
toIndex:int: index after the last bit to be cleared

Exceptions

IndexOutOfBoundsException:: if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex

Since

1.4

clear back to summary

clear	back to summary
public void clear() Sets all of the bits in this BitSet to `false`. Since 1.4

public void clear()

Sets all of the bits in this BitSet to false.

Since: 1.4

clone back to summary

clone	back to summary
public Object clone() Overrides java.lang.Object.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. Returns:Object a clone of this bit set See Also `size()`

public Object clone()

Overrides java.lang.Object.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.

Returns:Object: a clone of this bit set
See Also: size()

ensureCapacity	back to summary
private void ensureCapacity(int wordsRequired) Ensures that the BitSet can hold enough words. Parameters wordsRequired:int the minimum acceptable number of words.

ensureCapacity

back to summary

private void ensureCapacity(int wordsRequired)

Ensures that the BitSet can hold enough words.

Parameters

wordsRequired:int: the minimum acceptable number of words.

equals back to summary

equals	back to summary
public boolean equals(Object obj) Overrides java.lang.Object.equals. Compares this bit set 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`, ((BitSet)obj).get(k) == this.get(k) must be true. The current sizes of the two bit sets are not compared. Parameters obj:Object the object to compare with Returns:boolean `true` if the objects are the same; `false` otherwise Annotations @Override See Also `size()`

public boolean equals(Object obj)

Overrides java.lang.Object.equals.

Compares this bit set 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,

((BitSet)obj).get(k) == this.get(k)

must be true. The current sizes of the two bit sets are not compared.

Parameters

obj:Object: the object to compare with

Returns:boolean

true if the objects are the same; false otherwise

Annotations

@Override

See Also

size()

expandTo	back to summary
private void expandTo(int wordIndex) Ensures that the BitSet can accommodate a given wordIndex, temporarily violating the invariants. The caller must restore the invariants before returning to the user, possibly using recalculateWordsInUse(). Parameters wordIndex:int the index to be accommodated.

expandTo

back to summary

private void expandTo(int wordIndex)

Ensures that the BitSet can accommodate a given wordIndex, temporarily violating the invariants. The caller must restore the invariants before returning to the user, possibly using recalculateWordsInUse().

Parameters

wordIndex:int: the index to be accommodated.

flip	back to summary
public void flip(int bitIndex) Sets the bit at the specified index to the complement of its current value. Parameters bitIndex:int the index of the bit to flip Exceptions IndexOutOfBoundsException: if the specified index is negative Since 1.4

flip

back to summary

public void flip(int bitIndex)

Sets the bit at the specified index to the complement of its current value.

Parameters

bitIndex:int: the index of the bit to flip

Exceptions

IndexOutOfBoundsException:: if the specified index is negative

Since

1.4

flip back to summary

flip	back to summary
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. Parameters fromIndex:int index of the first bit to flip toIndex:int index after the last bit to flip Exceptions IndexOutOfBoundsException: if `fromIndex` is negative, or `toIndex` is negative, or `fromIndex` is larger than `toIndex` Since 1.4

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.

Parameters

fromIndex:int: index of the first bit to flip
toIndex:int: index after the last bit to flip

Exceptions

IndexOutOfBoundsException:: if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex

Since

1.4

get back to summary

get	back to summary
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`. Parameters bitIndex:int the bit index Returns:boolean the value of the bit with the specified index Exceptions IndexOutOfBoundsException: if the specified index is negative

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.

Parameters

bitIndex:int: the bit index

Returns:boolean

the value of the bit with the specified index

Exceptions

IndexOutOfBoundsException:: if the specified index is negative

get back to summary

get	back to summary
public BitSet get(int fromIndex, int toIndex) Returns a new `BitSet` composed of bits from this `BitSet` from `fromIndex` (inclusive) to `toIndex` (exclusive). Parameters fromIndex:int index of the first bit to include toIndex:int index after the last bit to include Returns:BitSet a new `BitSet` from a range of this `BitSet` Exceptions IndexOutOfBoundsException: if `fromIndex` is negative, or `toIndex` is negative, or `fromIndex` is larger than `toIndex` Since 1.4

public BitSet get(int fromIndex, int toIndex)

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

Parameters

fromIndex:int: index of the first bit to include
toIndex:int: index after the last bit to include

Returns:BitSet

a new BitSet from a range of this BitSet

Exceptions

IndexOutOfBoundsException:: if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex

Since

1.4

hashCode back to summary

hashCode	back to summary
public int hashCode() Overrides java.lang.Object.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); }` Note that the hash code changes if the set of bits is altered. Returns:int the hash code value for this bit set Annotations @Override

public int hashCode()

Overrides java.lang.Object.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);
}

Note that the hash code changes if the set of bits is altered.

Returns:int

the hash code value for this bit set

Annotations

@Override

initWords	back to summary
private void initWords(int nbits)

intersects back to summary

intersects	back to summary
public boolean intersects(BitSet set) Returns true if the specified `BitSet` has any bits set to `true` that are also set to `true` in this `BitSet`. Parameters set:BitSet `BitSet` to intersect with Returns:boolean boolean indicating whether this `BitSet` intersects the specified `BitSet` Since 1.4

public boolean intersects(BitSet set)

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

Parameters

set:BitSet: BitSet to intersect with

Returns:boolean

boolean indicating whether this BitSet intersects the specified BitSet

Since

1.4

isEmpty back to summary

isEmpty	back to summary
public boolean isEmpty() Returns true if this `BitSet` contains no bits that are set to `true`. Returns:boolean boolean indicating whether this `BitSet` is empty Since 1.4

public boolean isEmpty()

Returns true if this BitSet contains no bits that are set to true.

Returns:boolean: boolean indicating whether this BitSet is empty
Since: 1.4

length back to summary

length	back to summary
public int 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. Returns:int the logical size of this `BitSet` Since 1.2

public int 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.

Returns:int: the logical size of this BitSet
Since: 1.2

nextClearBit back to summary

nextClearBit	back to summary
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. Parameters fromIndex:int the index to start checking from (inclusive) Returns:int the index of the next clear bit Exceptions IndexOutOfBoundsException: if the specified index is negative Since 1.4

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.

Parameters

fromIndex:int: the index to start checking from (inclusive)

Returns:int

the index of the next clear bit

Exceptions

IndexOutOfBoundsException:: if the specified index is negative

Since

1.4

nextSetBit back to summary

nextSetBit	back to summary
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 } }` Parameters fromIndex:int the index to start checking from (inclusive) Returns:int the index of the next set bit, or `-1` if there is no such bit Exceptions IndexOutOfBoundsException: if the specified index is negative Since 1.4

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
    }
}

Parameters

fromIndex:int: the index to start checking from (inclusive)

Returns:int

the index of the next set bit, or -1 if there is no such bit

Exceptions

IndexOutOfBoundsException:: if the specified index is negative

Since

1.4

nextSetBit back to summary

nextSetBit	back to summary
private int nextSetBit(int fromIndex, int toWordIndex) Returns the index of the first bit that is set to `true` that occurs on or after the specified starting index and up to and including the specified word index If no such bit exists then `-1` is returned. Parameters fromIndex:int the index to start checking from (inclusive) toWordIndex:int the last word index to check (inclusive) Returns:int the index of the next set bit, or `-1` if there is no such bit

private int nextSetBit(int fromIndex, int toWordIndex)

Returns the index of the first bit that is set to true that occurs on or after the specified starting index and up to and including the specified word index If no such bit exists then -1 is returned.

Parameters

fromIndex:int: the index to start checking from (inclusive)
toWordIndex:int: the last word index to check (inclusive)

Returns:int

the index of the next set bit, or -1 if there is no such bit

or back to summary

or	back to summary
public void or(BitSet set) 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`. Parameters set:BitSet a bit set

public void or(BitSet set)

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.

Parameters

set:BitSet: a bit set

previousClearBit back to summary

previousClearBit	back to summary
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. Parameters fromIndex:int the index to start checking from (inclusive) Returns:int the index of the previous clear bit, or `-1` if there is no such bit Exceptions IndexOutOfBoundsException: if the specified index is less than `-1` Since 1.7

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.

Parameters

fromIndex:int: the index to start checking from (inclusive)

Returns:int

the index of the previous clear bit, or -1 if there is no such bit

Exceptions

IndexOutOfBoundsException:: if the specified index is less than -1

Since

1.7

previousSetBit back to summary

previousSetBit	back to summary
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 }` Parameters fromIndex:int the index to start checking from (inclusive) Returns:int the index of the previous set bit, or `-1` if there is no such bit Exceptions IndexOutOfBoundsException: if the specified index is less than `-1` Since 1.7

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
}

Parameters

fromIndex:int: the index to start checking from (inclusive)

Returns:int

the index of the previous set bit, or -1 if there is no such bit

Exceptions

IndexOutOfBoundsException:: if the specified index is less than -1

Since

1.7

readObject back to summary

readObject	back to summary
private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException Reconstitute the `BitSet` instance from a stream (i.e., deserialize it). Annotations @Serial

private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException

Reconstitute the BitSet instance from a stream (i.e., deserialize it).

Annotations

@Serial

recalculateWordsInUse	back to summary
private void recalculateWordsInUse() Sets the field wordsInUse to the logical size in words of the bit set. Warning This method assumes that the number of words actually in use is less than or equal to the current value of wordsInUse!

set back to summary

set	back to summary
public void set(int bitIndex) Sets the bit at the specified index to `true`. Parameters bitIndex:int a bit index Exceptions IndexOutOfBoundsException: if the specified index is negative Since 1.0

public void set(int bitIndex)

Sets the bit at the specified index to true.

Parameters

bitIndex:int: a bit index

Exceptions

IndexOutOfBoundsException:: if the specified index is negative

Since

1.0

set	back to summary
public void set(int bitIndex, boolean value) Sets the bit at the specified index to the specified value. Parameters bitIndex:int a bit index value:boolean a boolean value to set Exceptions IndexOutOfBoundsException: if the specified index is negative Since 1.4

set

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public void set(int bitIndex, boolean value)

Sets the bit at the specified index to the specified value.

Parameters

bitIndex:int: a bit index
value:boolean: a boolean value to set

Exceptions

IndexOutOfBoundsException:: if the specified index is negative

Since

1.4

set back to summary

set	back to summary
public void set(int fromIndex, int toIndex) Sets the bits from the specified `fromIndex` (inclusive) to the specified `toIndex` (exclusive) to `true`. Parameters fromIndex:int index of the first bit to be set toIndex:int index after the last bit to be set Exceptions IndexOutOfBoundsException: if `fromIndex` is negative, or `toIndex` is negative, or `fromIndex` is larger than `toIndex` Since 1.4

public void set(int fromIndex, int toIndex)

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

Parameters

fromIndex:int: index of the first bit to be set
toIndex:int: index after the last bit to be set

Exceptions

IndexOutOfBoundsException:: if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex

Since

1.4

set back to summary

set	back to summary
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. Parameters fromIndex:int index of the first bit to be set toIndex:int index after the last bit to be set value:boolean value to set the selected bits to Exceptions IndexOutOfBoundsException: if `fromIndex` is negative, or `toIndex` is negative, or `fromIndex` is larger than `toIndex` Since 1.4

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.

Parameters

fromIndex:int: index of the first bit to be set
toIndex:int: index after the last bit to be set
value:boolean: value to set the selected bits to

Exceptions

IndexOutOfBoundsException:: if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex

Since

1.4

size back to summary

size	back to summary
public int 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. Returns:int the number of bits currently in this bit set

public int 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.

Returns:int: the number of bits currently in this bit set

stream back to summary

stream	back to summary
public IntStream 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. Returns:IntStream a stream of integers representing set indices Since 1.8

public IntStream 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.

Returns:IntStream: a stream of integers representing set indices
Since: 1.8

toByteArray back to summary

public byte[] 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.

Returns:byte[]: a byte array containing a little-endian representation of all the bits in this bit set
Since: 1.7

toLongArray back to summary

public long[] 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.

Returns:long[]: a long array containing a little-endian representation of all the bits in this bit set
Since: 1.7

toString back to summary

public String toString()

Overrides java.lang.Object.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();

Now drPepper.toString() returns "{}".

drPepper.set(2);

Now drPepper.toString() returns "{2}".

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

Now drPepper.toString() returns "{2, 4, 10}".

Returns:String: a string representation of this bit set

trimToSize	back to summary
private void trimToSize() Attempts to reduce internal storage used for the bits in this bit set. Calling this method may, but is not required to, affect the value returned by a subsequent call to the `size()` method.

valueOf back to summary

public static BitSet valueOf(long[] longs)

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)).

Parameters

longs:long[]: a long array containing a little-endian representation of a sequence of bits to be used as the initial bits of the new bit set

Returns:BitSet

a BitSet containing all the bits in the long array

Since

1.7

valueOf back to summary

public static BitSet valueOf(LongBuffer lb)

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.

Parameters

lb:LongBuffer: a long buffer containing a little-endian representation of a sequence of bits between its position and limit, to be used as the initial bits of the new bit set

Returns:BitSet

a BitSet containing all the bits in the buffer in the specified range

Since

1.7

valueOf back to summary

public static BitSet valueOf(byte[] bytes)

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)).

Parameters

bytes:byte[]: a byte array containing a little-endian representation of a sequence of bits to be used as the initial bits of the new bit set

Returns:BitSet

a BitSet containing all the bits in the byte array

Since

1.7

valueOf back to summary

public static BitSet valueOf(ByteBuffer bb)

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.

Parameters

bb:ByteBuffer: a byte buffer containing a little-endian representation of a sequence of bits between its position and limit, to be used as the initial bits of the new bit set

Returns:BitSet

a BitSet containing all the bits in the buffer in the specified range

Since

1.7

wordIndex	back to summary
private static int wordIndex(int bitIndex) Given a bit index, return word index containing it.

writeObject back to summary

private void writeObject(ObjectOutputStream s) throws IOException

Save the state of the BitSet instance to a stream (i.e., serialize it).

Annotations

@Serial

xor back to summary

public void xor(BitSet set)

Performs a logical XOR 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 one of the following statements holds:

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.

Parameters

set:BitSet: a bit set

public Class BitSet

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