Guava: Google Core Libraries for Java 32.1.2-jre · com.google.common.math.IntMath

Modifier and Type	Field and Description
pack-priv static int[]	biggestBinomials
private static final int[]	factorials
pack-priv static final int	FLOOR_SQRT_MAX_INT
pack-priv static final int[]	halfPowersOf10
pack-priv static final int	MAX_POWER_OF_SQRT2_UNSIGNED The biggest half power of two that can fit in an unsigned int.
pack-priv static final int	MAX_SIGNED_POWER_OF_TWO
pack-priv static final byte[]	maxLog10ForLeadingZeros
pack-priv static final int[]	powersOf10

Access	Constructor and Description
private	IntMath()

Method Summary

Modifier and Type	Method and Description
public static int	binomial(int n, int k) Returns `n` choose `k`, also known as the binomial coefficient of `n` and `k`, or `Integer#MAX_VALUE` if the result does not fit in an `int`.
public static int	ceilingPowerOfTwo(int x) Returns the smallest power of two greater than or equal to `x`.
public static int	checkedAdd(int a, int b) Returns the sum of `a` and `b`, provided it does not overflow.
public static int	checkedMultiply(int a, int b) Returns the product of `a` and `b`, provided it does not overflow.
public static int	checkedPow(int b, int k) Returns the `b` to the `k`th power, provided it does not overflow.
public static int	checkedSubtract(int a, int b) Returns the difference of `a` and `b`, provided it does not overflow.
public static int	divide(int p, int q, RoundingMode mode) Returns the result of dividing `p` by `q`, rounding using the specified `RoundingMode`.
public static int	factorial(int n) Returns `n!`
public static int	floorPowerOfTwo(int x) Returns the largest power of two less than or equal to `x`.
public static int	gcd(int a, int b) Returns the greatest common divisor of `a, b`.
public static boolean	isPowerOfTwo(int x) Returns `true` if `x` represents a power of two.
public static boolean	isPrime(int n) Returns `true` if `n` is a prime number: an integer greater than one that cannot be factored into a product of smaller positive integers.
pack-priv static int	lessThanBranchFree(int x, int y) Returns 1 if `x < y` as unsigned integers, and 0 otherwise.
public static int	log10(int x, RoundingMode mode) Returns the base-10 logarithm of `x`, rounded according to the specified rounding mode.
private static int	log10Floor(int x)
public static int	log2(int x, RoundingMode mode) Returns the base-2 logarithm of `x`, rounded according to the specified rounding mode.
public static int	mean(int x, int y) Returns the arithmetic mean of `x` and `y`, rounded towards negative infinity.
public static int	mod(int x, int m) Returns `x mod m`, a non-negative value less than `m`.
public static int	pow(int b, int k) Returns `b` to the `k`th power.
public static int	saturatedAdd(int a, int b) Returns the sum of `a` and `b` unless it would overflow or underflow in which case `Integer.MAX_VALUE` or `Integer.MIN_VALUE` is returned, respectively.
public static int	saturatedMultiply(int a, int b) Returns the product of `a` and `b` unless it would overflow or underflow in which case `Integer.MAX_VALUE` or `Integer.MIN_VALUE` is returned, respectively.
public static int	saturatedPow(int b, int k) Returns the `b` to the `k`th power, unless it would overflow or underflow in which case `Integer.MAX_VALUE` or `Integer.MIN_VALUE` is returned, respectively.
public static int	saturatedSubtract(int a, int b) Returns the difference of `a` and `b` unless it would overflow or underflow in which case `Integer.MAX_VALUE` or `Integer.MIN_VALUE` is returned, respectively.
public static int	sqrt(int x, RoundingMode mode) Returns the square root of `x`, rounded with the specified rounding mode.
private static int	sqrtFloor(int x)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

biggestBinomials	back to summary
pack-priv static int[] biggestBinomials Annotations @VisibleForTesting

factorials	back to summary
private static final int[] factorials

FLOOR_SQRT_MAX_INT	back to summary
pack-priv static final int FLOOR_SQRT_MAX_INT Annotations @VisibleForTesting

halfPowersOf10	back to summary
pack-priv static final int[] halfPowersOf10 Annotations @VisibleForTesting

MAX_POWER_OF_SQRT2_UNSIGNED	back to summary
pack-priv static final int MAX_POWER_OF_SQRT2_UNSIGNED The biggest half power of two that can fit in an unsigned int. Annotations @VisibleForTesting

MAX_SIGNED_POWER_OF_TWO	back to summary
pack-priv static final int MAX_SIGNED_POWER_OF_TWO Annotations @VisibleForTesting

maxLog10ForLeadingZeros	back to summary
pack-priv static final byte[] maxLog10ForLeadingZeros Annotations @VisibleForTesting

powersOf10	back to summary
pack-priv static final int[] powersOf10 Annotations @VisibleForTesting

IntMath	back to summary
private IntMath()

Method Detail

binomial back to summary

binomial	back to summary
public static int binomial(int n, int k) Returns `n` choose `k`, also known as the binomial coefficient of `n` and `k`, or `Integer#MAX_VALUE` if the result does not fit in an `int`. Exceptions IllegalArgumentException: if `n < 0`, `k < 0` or `k > n`

public static int binomial(int n, int k)

Returns n choose k, also known as the binomial coefficient of n and k, or Integer#MAX_VALUE if the result does not fit in an int.

Exceptions

IllegalArgumentException:: if n < 0, k < 0 or k > n

ceilingPowerOfTwo back to summary

ceilingPowerOfTwo	back to summary
public static int ceilingPowerOfTwo(int x) Returns the smallest power of two greater than or equal to `x`. This is equivalent to `checkedPow(2, log2(x, CEILING))`. Exceptions IllegalArgumentException: if `x <= 0` ArithmeticException: of the next-higher power of two is not representable as an `int`, i.e. when `x > 2^30` Since 20.0

public static int ceilingPowerOfTwo(int x)

Returns the smallest power of two greater than or equal to x. This is equivalent to checkedPow(2, log2(x, CEILING)).

Exceptions

IllegalArgumentException:: if x <= 0
ArithmeticException:: of the next-higher power of two is not representable as an int, i.e. when x > 2^30

Since

20.0

checkedAdd back to summary

checkedAdd	back to summary
public static int checkedAdd(int a, int b) Returns the sum of `a` and `b`, provided it does not overflow. Exceptions ArithmeticException: if `a + b` overflows in signed `int` arithmetic

public static int checkedAdd(int a, int b)

Returns the sum of a and b, provided it does not overflow.

Exceptions

ArithmeticException:: if a + b overflows in signed int arithmetic

checkedMultiply back to summary

checkedMultiply	back to summary
public static int checkedMultiply(int a, int b) Returns the product of `a` and `b`, provided it does not overflow. Exceptions ArithmeticException: if `a * b` overflows in signed `int` arithmetic

public static int checkedMultiply(int a, int b)

Returns the product of a and b, provided it does not overflow.

Exceptions

ArithmeticException:: if a * b overflows in signed int arithmetic

checkedPow back to summary

checkedPow	back to summary
public static int checkedPow(int b, int k) Returns the `b` to the `k`th power, provided it does not overflow. `pow` may be faster, but does not check for overflow. Exceptions ArithmeticException: if `b` to the `k`th power overflows in signed `int` arithmetic

public static int checkedPow(int b, int k)

Returns the b to the kth power, provided it does not overflow.

pow may be faster, but does not check for overflow.

Exceptions

ArithmeticException:: if b to the kth power overflows in signed int arithmetic

checkedSubtract back to summary

checkedSubtract	back to summary
public static int checkedSubtract(int a, int b) Returns the difference of `a` and `b`, provided it does not overflow. Exceptions ArithmeticException: if `a - b` overflows in signed `int` arithmetic

public static int checkedSubtract(int a, int b)

Returns the difference of a and b, provided it does not overflow.

Exceptions

ArithmeticException:: if a - b overflows in signed int arithmetic

divide back to summary

divide	back to summary
public static int divide(int p, int q, RoundingMode mode) Returns the result of dividing `p` by `q`, rounding using the specified `RoundingMode`. Annotations @SuppressWarnings:fallthrough Exceptions ArithmeticException: if `q == 0`, or if `mode == UNNECESSARY` and `a` is not an integer multiple of `b`

public static int divide(int p, int q, RoundingMode mode)

Returns the result of dividing p by q, rounding using the specified RoundingMode.

Annotations

@SuppressWarnings:fallthrough

Exceptions

ArithmeticException:: if q == 0, or if mode == UNNECESSARY and a is not an integer multiple of b

factorial back to summary

factorial	back to summary
public static int factorial(int n) Returns `n!`, that is, the product of the first `n` positive integers, `1` if `n == 0`, or `Integer#MAX_VALUE` if the result does not fit in a `int`. Exceptions IllegalArgumentException: if `n < 0`

public static int factorial(int n)

Returns n!, that is, the product of the first n positive integers, 1 if n == 0, or Integer#MAX_VALUE if the result does not fit in a int.

Exceptions

IllegalArgumentException:: if n < 0

floorPowerOfTwo back to summary

floorPowerOfTwo	back to summary
public static int floorPowerOfTwo(int x) Returns the largest power of two less than or equal to `x`. This is equivalent to `checkedPow(2, log2(x, FLOOR))`. Exceptions IllegalArgumentException: if `x <= 0` Since 20.0

public static int floorPowerOfTwo(int x)

Returns the largest power of two less than or equal to x. This is equivalent to checkedPow(2, log2(x, FLOOR)).

Exceptions

IllegalArgumentException:: if x <= 0

Since

20.0

gcd back to summary

gcd	back to summary
public static int gcd(int a, int b) Returns the greatest common divisor of `a, b`. Returns `0` if `a == 0 && b == 0`. Exceptions IllegalArgumentException: if `a < 0` or `b < 0`

public static int gcd(int a, int b)

Returns the greatest common divisor of a, b. Returns 0 if a == 0 && b == 0.

Exceptions

IllegalArgumentException:: if a < 0 or b < 0

isPowerOfTwo back to summary

isPowerOfTwo	back to summary
public static boolean isPowerOfTwo(int x) Returns `true` if `x` represents a power of two. This differs from `Integer.bitCount(x) == 1`, because `Integer.bitCount(Integer.MIN_VALUE) == 1`, but `Integer#MIN_VALUE` is not a power of two.

public static boolean isPowerOfTwo(int x)

Returns true if x represents a power of two.

This differs from Integer.bitCount(x) == 1, because Integer.bitCount(Integer.MIN_VALUE) == 1, but Integer#MIN_VALUE is not a power of two.

isPrime back to summary

isPrime	back to summary
public static boolean isPrime(int n) Returns `true` if `n` is a prime number: an integer greater than one that cannot be factored into a product of smaller positive integers. Returns `false` if `n` is zero, one, or a composite number (one which can be factored into smaller positive integers). To test larger numbers, use `LongMath#isPrime` or `BigInteger#isProbablePrime`. Annotations @J2ktIncompatible @GwtIncompatible Exceptions IllegalArgumentException: if `n` is negative Since 20.0

public static boolean isPrime(int n)

Returns true if n is a prime number: an integer greater than one that cannot be factored into a product of smaller positive integers. Returns false if n is zero, one, or a composite number (one which can be factored into smaller positive integers).

To test larger numbers, use LongMath#isPrime or BigInteger#isProbablePrime.

Annotations

@J2ktIncompatible
@GwtIncompatible

Exceptions

IllegalArgumentException:: if n is negative

Since

20.0

lessThanBranchFree back to summary

lessThanBranchFree	back to summary
pack-priv static int lessThanBranchFree(int x, int y) Returns 1 if `x < y` as unsigned integers, and 0 otherwise. Assumes that x - y fits into a signed int. The implementation is branch-free, and benchmarks suggest it is measurably (if narrowly) faster than the straightforward ternary expression. Annotations @VisibleForTesting

pack-priv static int lessThanBranchFree(int x, int y)

Returns 1 if x < y as unsigned integers, and 0 otherwise. Assumes that x - y fits into a signed int. The implementation is branch-free, and benchmarks suggest it is measurably (if narrowly) faster than the straightforward ternary expression.

Annotations

@VisibleForTesting

log10 back to summary

log10	back to summary
public static int log10(int x, RoundingMode mode) Returns the base-10 logarithm of `x`, rounded according to the specified rounding mode. Annotations @J2ktIncompatible @GwtIncompatible @SuppressWarnings:fallthrough Exceptions IllegalArgumentException: if `x <= 0` ArithmeticException: if `mode` is `RoundingMode#UNNECESSARY` and `x` is not a power of ten

public static int log10(int x, RoundingMode mode)

Returns the base-10 logarithm of x, rounded according to the specified rounding mode.

Annotations

@J2ktIncompatible
@GwtIncompatible
@SuppressWarnings:fallthrough

Exceptions

IllegalArgumentException:: if x <= 0
ArithmeticException:: if mode is RoundingMode#UNNECESSARY and x is not a power of ten

log10Floor	back to summary
private static int log10Floor(int x)

log2 back to summary

log2	back to summary
public static int log2(int x, RoundingMode mode) Returns the base-2 logarithm of `x`, rounded according to the specified rounding mode. Annotations @SuppressWarnings:fallthrough Exceptions IllegalArgumentException: if `x <= 0` ArithmeticException: if `mode` is `RoundingMode#UNNECESSARY` and `x` is not a power of two

public static int log2(int x, RoundingMode mode)

Returns the base-2 logarithm of x, rounded according to the specified rounding mode.

Annotations

@SuppressWarnings:fallthrough

Exceptions

IllegalArgumentException:: if x <= 0
ArithmeticException:: if mode is RoundingMode#UNNECESSARY and x is not a power of two

mean back to summary

mean	back to summary
public static int mean(int x, int y) Returns the arithmetic mean of `x` and `y`, rounded towards negative infinity. This method is overflow resilient. Since 14.0

public static int mean(int x, int y)

Returns the arithmetic mean of x and y, rounded towards negative infinity. This method is overflow resilient.

Since: 14.0

mod back to summary

mod	back to summary
public static int mod(int x, int m) Returns `x mod m`, a non-negative value less than `m`. This differs from `x % m`, which might be negative. For example: `mod(7, 4) == 3 mod(-7, 4) == 1 mod(-1, 4) == 3 mod(-8, 4) == 0 mod(8, 4) == 0` Exceptions ArithmeticException: if `m <= 0` See Also Remainder Operator

public static int mod(int x, int m)

Returns x mod m, a non-negative value less than m. This differs from x % m, which might be negative.

For example:

mod(7, 4) == 3
mod(-7, 4) == 1
mod(-1, 4) == 3
mod(-8, 4) == 0
mod(8, 4) == 0

Exceptions

ArithmeticException:: if m <= 0

See Also

Remainder Operator

pow back to summary

pow	back to summary
public static int pow(int b, int k) Returns `b` to the `k`th power. Even if the result overflows, it will be equal to `BigInteger.valueOf(b).pow(k).intValue()`. This implementation runs in `O(log k)` time. Compare `checkedPow`, which throws an `ArithmeticException` upon overflow. Annotations @J2ktIncompatible @GwtIncompatible Exceptions IllegalArgumentException: if `k < 0`

public static int pow(int b, int k)

Returns b to the kth power. Even if the result overflows, it will be equal to BigInteger.valueOf(b).pow(k).intValue(). This implementation runs in O(log k) time.

Compare checkedPow, which throws an ArithmeticException upon overflow.

Annotations

@J2ktIncompatible
@GwtIncompatible

Exceptions

IllegalArgumentException:: if k < 0

saturatedAdd back to summary

saturatedAdd	back to summary
public static int saturatedAdd(int a, int b) Returns the sum of `a` and `b` unless it would overflow or underflow in which case `Integer.MAX_VALUE` or `Integer.MIN_VALUE` is returned, respectively. Since 20.0

public static int saturatedAdd(int a, int b)

Returns the sum of a and b unless it would overflow or underflow in which case Integer.MAX_VALUE or Integer.MIN_VALUE is returned, respectively.

Since: 20.0

saturatedMultiply back to summary

saturatedMultiply	back to summary
public static int saturatedMultiply(int a, int b) Returns the product of `a` and `b` unless it would overflow or underflow in which case `Integer.MAX_VALUE` or `Integer.MIN_VALUE` is returned, respectively. Since 20.0

public static int saturatedMultiply(int a, int b)

Returns the product of a and b unless it would overflow or underflow in which case Integer.MAX_VALUE or Integer.MIN_VALUE is returned, respectively.

Since: 20.0

saturatedPow back to summary

saturatedPow	back to summary
public static int saturatedPow(int b, int k) Returns the `b` to the `k`th power, unless it would overflow or underflow in which case `Integer.MAX_VALUE` or `Integer.MIN_VALUE` is returned, respectively. Since 20.0

public static int saturatedPow(int b, int k)

Returns the b to the kth power, unless it would overflow or underflow in which case Integer.MAX_VALUE or Integer.MIN_VALUE is returned, respectively.

Since: 20.0

saturatedSubtract back to summary

saturatedSubtract	back to summary
public static int saturatedSubtract(int a, int b) Returns the difference of `a` and `b` unless it would overflow or underflow in which case `Integer.MAX_VALUE` or `Integer.MIN_VALUE` is returned, respectively. Since 20.0

public static int saturatedSubtract(int a, int b)

Returns the difference of a and b unless it would overflow or underflow in which case Integer.MAX_VALUE or Integer.MIN_VALUE is returned, respectively.

Since: 20.0

sqrt back to summary

sqrt	back to summary
public static int sqrt(int x, RoundingMode mode) Returns the square root of `x`, rounded with the specified rounding mode. Annotations @GwtIncompatible @SuppressWarnings:fallthrough Exceptions IllegalArgumentException: if `x < 0` ArithmeticException: if `mode` is `RoundingMode#UNNECESSARY` and `sqrt(x)` is not an integer

public static int sqrt(int x, RoundingMode mode)

Returns the square root of x, rounded with the specified rounding mode.

Annotations

@GwtIncompatible
@SuppressWarnings:fallthrough

Exceptions

IllegalArgumentException:: if x < 0
ArithmeticException:: if mode is RoundingMode#UNNECESSARY and sqrt(x) is not an integer

sqrtFloor	back to summary
private static int sqrtFloor(int x)

public final Class IntMath

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