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2017-03-07
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BigInteger

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Introduction

The BigInteger class is used for mathematical operations involving large integers with magnitudes too large for primitive data types. For example 100-factorial is 158 digits - much larger than a long can represent. BigInteger provides analogues to all of Java's primitive integer operators, and all relevant methods from java.lang.Math as well as few other operations.

Syntax

  • BigInteger variable_name = new BigInteger("12345678901234567890"); // a decimal integer as a string
  • BigInteger variable_name = new BigInteger("1010101101010100101010011000110011101011000111110000101011010010", 2) // a binary integer as a string
  • BigInteger variable_name = new BigInteger("ab54a98ceb1f0800", 16) // a hexadecimal integer as a string
  • BigInteger variable_name = new BigInteger(64, new Random()); // a pseudorandom number generator supplying 64 bits to construct an integer
  • BigInteger variable_name = new BigInteger(new byte[]{0, -85, 84, -87, -116, -21, 31, 10, -46}); // signed two's complement representation of an integer (big endian)
  • BigInteger variable_name = new BigInteger(1, new byte[]{-85, 84, -87, -116, -21, 31, 10, -46}); // unsigned two's complement representation of a positive integer (big endian)

Remarks

BigInteger is immutable. Therefore you can't change its state. For example, the following won't work as sum won't be updated due to immutability.

BigInteger sum = BigInteger.ZERO;
for(int i = 1; i < 5000; i++) {
   sum.add(BigInteger.valueOf(i));  
}

Assign the result to the sum variable to make it work.

sum = sum.add(BigInteger.valueOf(i));

Java SE 8

The official documentation of BigInteger states that BigInteger implementations should support all integers between -22147483647 and 22147483647 (exclusive). This means BigIntegers can have more than 2 billion bits!

Related Examples