java.math.BigInteger.bitLength()方法的使用及代码示例

x33g5p2x  于2022-01-16 转载在 其他  
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本文整理了Java中java.math.BigInteger.bitLength()方法的一些代码示例，展示了BigInteger.bitLength()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。BigInteger.bitLength()方法的具体详情如下：
包路径：java.math.BigInteger
类名称：BigInteger
方法名：bitLength

BigInteger.bitLength介绍

[英]One plus the bitLength of this BigInteger. Zeros means unitialized. (either value is acceptable).
[中]一加上这个大整数的位长度。零表示单位化。（任一值均可接受）。

代码示例

代码示例来源：origin: google/guava

/** Returns {@code true} if {@code x} represents a power of two. */
public static boolean isPowerOfTwo(BigInteger x) {
 checkNotNull(x);
 return x.signum() > 0 && x.getLowestSetBit() == x.bitLength() - 1;
}

代码示例来源：origin: plutext/docx4j

public boolean isBelowMaxRep() {
  int sc = _significand.bitLength() - C_64;
  return _significand.compareTo(BI_MAX_BASE.shiftLeft(sc)) < 0;
}
public boolean isAboveMinRep() {

代码示例来源：origin: plutext/docx4j

private void mulShift(BigInteger multiplicand, int multiplierShift) {
  _significand = _significand.multiply(multiplicand);
  _binaryExponent += multiplierShift;
  // check for too much precision
  int sc = (_significand.bitLength() - MIN_PRECISION) & 0xFFFFFFE0;
  // mask makes multiples of 32 which optimises BigInteger.shiftRight
  if (sc > 0) {
    // no need to round because we have at least 8 bits of extra precision
    _significand = _significand.shiftRight(sc);
    _binaryExponent += sc;
  }
}

代码示例来源：origin: stackoverflow.com

int nlen = n.bitLength();
BigInteger nm1 = n.subtract(BigInteger.ONE);
BigInteger r, s;
do {
  s = new BigInteger(nlen + 100, rnd);
  r = s.mod(n);
} while (s.subtract(r).add(nm1).bitLength() >= nlen + 100);
// result is in 'r'

代码示例来源：origin: org.apache.ant/ant

private static long parseBinaryBigInteger(final byte[] buffer,
                     final int offset,
                     final int length,
                     final boolean negative) {
  final byte[] remainder = new byte[length - 1];
  System.arraycopy(buffer, offset + 1, remainder, 0, length - 1);
  BigInteger val = new BigInteger(remainder);
  if (negative) {
    // 2's complement
    val = val.add(BigInteger.valueOf(-1)).not();
  }
  if (val.bitLength() > 63) {
    throw new IllegalArgumentException(String.format(
        "At offset %d, %d byte binary number exceeds maximum signed long value",
        offset, length));
  }
  return negative ? -val.longValue() : val.longValue();
}

代码示例来源：origin: stackoverflow.com

public BigInteger nextRandomBigInteger(BigInteger n) {
  Random rand = new Random();
  BigInteger result = new BigInteger(n.bitLength(), rand);
  while( result.compareTo(n) >= 0 ) {
    result = new BigInteger(n.bitLength(), rand);
  }
  return result;
}

代码示例来源：origin: stackoverflow.com

public static BigInteger random(Random rand, BigInteger minValue, BigInteger maxValue) {
  BigInteger range = maxValue.subtract(minValue).add(BigInteger.ONE);
  int bits = range.bitLength();
  BigInteger ret;
  do {
    ret = new BigInteger(bits, rand);
  } while(ret.compareTo(range) >= 0);
  return ret.add(minValue);
}

代码示例来源：origin: i2p/i2p.i2p

/** @return 0 to max-1 or -1 for us */
public int getRange(T key) {
  Integer rv;
  synchronized (_distanceCache) {
    rv = _distanceCache.get(key);
    if (rv == null) {
      // easy way when _bValue == 1
      //rv = Integer.valueOf(_bigUs.xor(new BigInteger(1, key.getData())).bitLength() - 1);
      BigInteger xor = _bigUs.xor(new BigInteger(1, key.getData()));
      int range = xor.bitLength() - 1;
      if (_bValue > 1) {
        int toShift = range + 1 - _bValue;
        int highbit = range;
        range <<= _bValue - 1;
        if (toShift >= 0) {
          int extra = xor.clearBit(highbit).shiftRight(toShift).intValue();
          range += extra;
          //Log log = I2PAppContext.getGlobalContext().logManager().getLog(KBucketSet.class);
          //if (log.shouldLog(Log.DEBUG))
          //    log.debug("highbit " + highbit + " toshift " + toShift + " extra " + extra + " new " + range);
        }
      }
      rv = Integer.valueOf(range);
      _distanceCache.put(key, rv);
    }
  }
  return rv.intValue();
}

代码示例来源：origin: plantuml/plantuml

public BigDecimal eval(List<? extends Number> parameters) {
    assertNotNull(parameters.get(0));
    /*
     * From The Java Programmers Guide To numerical Computing (Ronald Mak, 2003)
     */
    BigDecimal x = (BigDecimal) parameters.get(0);
    if (x.compareTo(BigDecimal.ZERO) == 0) {
      return new BigDecimal(0);
    }
    if (x.signum() < 0) {
      throw new ExpressionException("Argument to SQRT() function must not be negative");
    }
    BigInteger n = x.movePointRight(mc.getPrecision() << 1).toBigInteger();
    int bits = (n.bitLength() + 1) >> 1;
    BigInteger ix = n.shiftRight(bits);
    BigInteger ixPrev;
    BigInteger test;
    do {
      ixPrev = ix;
      ix = ix.add(n.divide(ix)).shiftRight(1);
      // Give other threads a chance to work;
      Thread.yield();
      test = ix.subtract(ixPrev).abs();
    } while (test.compareTo(BigInteger.ZERO) != 0 && test.compareTo(BigInteger.ONE) != 0);
    return new BigDecimal(ix, mc.getPrecision());
  }
});

代码示例来源：origin: robovm/robovm

if (this.a.signum() < 0 || this.a.compareTo(p) >= 0) {
  throw new IllegalArgumentException("the a is not in the field");
if (this.b.signum() < 0 || this.b.compareTo(p) >= 0) {
  throw new IllegalArgumentException("the b is not in the field");
if (!(this.a.bitLength() <= fieldSizeInBits)) {
  throw new IllegalArgumentException("the a is not in the field");
if (!(this.b.bitLength() <= fieldSizeInBits)) {
  throw new IllegalArgumentException("the b is not in the field");

代码示例来源：origin: google/guava

int logFloor = x.bitLength() - 1;
switch (mode) {
 case UNNECESSARY:
  if (logFloor < SQRT2_PRECOMPUTE_THRESHOLD) {
   BigInteger halfPower =
     SQRT2_PRECOMPUTED_BITS.shiftRight(SQRT2_PRECOMPUTE_THRESHOLD - logFloor);
   if (x.compareTo(halfPower) <= 0) {
    return logFloor;
   } else {
  int logX2Floor = x2.bitLength() - 1;
  return (logX2Floor < 2 * logFloor + 1) ? logFloor : logFloor + 1;

代码示例来源：origin: pholser/junit-quickcheck

public static BigInteger choose(
  SourceOfRandomness random,
  BigInteger min,
  BigInteger max) {
  BigInteger range = max.subtract(min).add(BigInteger.ONE);
  BigInteger generated;
  do {
    generated = random.nextBigInteger(range.bitLength());
  } while (generated.compareTo(range) >= 0);
  return generated.add(min);
}

代码示例来源：origin: org.apache.commons/commons-lang3

final BigInteger t = isAdd ? uvp.add(upv) : uvp.subtract(upv);
if (w.bitLength() > 31) {
  throw new ArithmeticException("overflow: numerator too large after multiply");

代码示例来源：origin: google/guava

static double bigToDouble(BigInteger x) {
 int exponent = absX.bitLength() - 1;
  return x.signum() * POSITIVE_INFINITY;
 long twiceSignifFloor = absX.shiftRight(shift).longValue();
 long signifFloor = twiceSignifFloor >> 1;
 bits |= x.signum() & SIGN_MASK;
 return longBitsToDouble(bits);

代码示例来源：origin: pholser/junit-quickcheck

@Override protected void primeSourceOfRandomness() {
  numberOfBits = max.movePointRight(3).subtract(min.movePointRight(3)).toBigInteger().bitLength();
  when(randomForParameterGenerator.nextBigInteger(numberOfBits))
    .thenReturn(new BigInteger("2").pow(numberOfBits).subtract(ONE))
    .thenReturn(ONE)
    .thenReturn(TEN)
    .thenReturn(ZERO)
    .thenReturn(new BigInteger("234234234234"));
}

代码示例来源：origin: org.apache.commons/commons-compress

private static long parseBinaryBigInteger(final byte[] buffer,
                     final int offset,
                     final int length,
                     final boolean negative) {
  final byte[] remainder = new byte[length - 1];
  System.arraycopy(buffer, offset + 1, remainder, 0, length - 1);
  BigInteger val = new BigInteger(remainder);
  if (negative) {
    // 2's complement
    val = val.add(BigInteger.valueOf(-1)).not();
  }
  if (val.bitLength() > 63) {
    throw new IllegalArgumentException("At offset " + offset + ", "
                      + length + " byte binary number"
                      + " exceeds maximum signed long"
                      + " value");
  }
  return negative ? -val.longValue() : val.longValue();
}

代码示例来源：origin: stackoverflow.com

X9ECParameters x9 = NISTNamedCurves.getByName("P-224"); // or whatever curve you want to use
ECPoint g = x9.getG();
BigInteger n = x9.getN();
int nBitLength = n.bitLength();
BigInteger x;
do
{
  x = new BigInteger(nBitLength, random);
}
while (x.equals(ZERO)  || (x.compareTo(n) >= 0));
ECPoint randomPoint = g.multiply(x);

代码示例来源：origin: stackoverflow.com

public static int myRandom(int min, int max, Random r){
  if (max <= min)
    throw new RuntimeException("max value must be greater than min value: max="+max +", min="+min);

  BigInteger maxB = BigInteger.valueOf(max);
  BigInteger minB = BigInteger.valueOf(min);

  BigInteger range = maxB.subtract(minB);
  do{
    BigInteger result = new BigInteger(range.bitLength(), r);
    if (result.compareTo(range)<=0)
      return result.add(minB).intValueExact();
  }while(true);
}

代码示例来源：origin: com.madgag.spongycastle/core

private BigInteger bitsToInt(byte[] t)
  {
    BigInteger v = new BigInteger(1, t);

    if (t.length * 8 > n.bitLength())
    {
      v = v.shiftRight(t.length * 8 - n.bitLength());
    }

    return v;
  }
}

代码示例来源：origin: prestodb/presto

private static void writeBigInteger(OutputStream output, BigInteger value)
      throws IOException
  {
    // encode the signed number as a positive integer
    value = value.shiftLeft(1);
    int sign = value.signum();
    if (sign < 0) {
      value = value.negate();
      value = value.subtract(ONE);
    }
    int length = value.bitLength();
    while (true) {
      long lowBits = value.longValue() & 0x7fffffffffffffffL;
      length -= 63;
      // write out the next 63 bits worth of data
      for (int i = 0; i < 9; ++i) {
        // if this is the last byte, leave the high bit off
        if (length <= 0 && (lowBits & ~0x7f) == 0) {
          output.write((byte) lowBits);
          return;
        }
        else {
          output.write((byte) (0x80 | (lowBits & 0x7f)));
          lowBits >>>= 7;
        }
      }
      value = value.shiftRight(63);
    }
  }
}

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