BigInteger和BigDecimal常用方法详解

BigInteger

add

实现两个BigInteger相加，返回相加后的结果，不影响原来的数据

public BigInteger add(BigInteger val)

BigInteger num1 = new BigInteger("1");
BigInteger num2 = new BigInteger("2");
// num3 = num1 + num2
BigInteger num3 = num1.add(num2);
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num3 = " + num3);
// 输出结果：
// num1 = 1
// num2 = 2
// num3 = 3

subtract

实现两个BigInteger相减，返回相减后的结果，不影响原来的数据

public BigInteger subtract(BigInteger val)

BigInteger num1 = new BigInteger("1");
BigInteger num2 = new BigInteger("2");
// num3 = num1 - num2
BigInteger num3 = num1.subtract(num2);
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num3 = " + num3);
// 输出结果：
// num1 = 1
// num2 = 2
// num3 = -1

multiply

实现两个BigInteger相乘，返回相乘后的结果，不影响原来的数据

public BigInteger multiply(BigInteger val)

BigInteger num1 = new BigInteger("1");
BigInteger num2 = new BigInteger("2");
// num3 = num1 * num2
BigInteger num3 = num1.multiply(num2);
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num3 = " + num3);
// 输出结果：
// num1 = 1
// num2 = 2
// num3 = 2

divide

实现两个BigInteger相除，返回相除后的结果，不影响原来的数据

public BigInteger divide(BigInteger val)

BigInteger num1 = new BigInteger("4");
BigInteger num2 = new BigInteger("2");
// num3 = num1 / num2
BigInteger num3 = num1.divide(num2);
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num3 = " + num3);
// 输出结果：
// num1 = 4
// num2 = 2
// num3 = 2

mod

实现实现两个BigInteger取模，返回取模后的结果，不影响原来的数据

public BigInteger mod(BigInteger m)

BigInteger num1 = new BigInteger("4");
BigInteger num2 = new BigInteger("2");
// num3 = num1 % num2
BigInteger num3 = num1.mod(num2);
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num3 = " + num3);
// 输出结果：
// num1 = 4
// num2 = 2
// num3 = 0

gcd

求两个BigInteger的最小公因数，不影响原来的数据

public BigInteger gcd(BigInteger val)

BigInteger num1 = new BigInteger("4");
BigInteger num2 = new BigInteger("2");
// num3 = gcd(num1, num2)
BigInteger num3 = num1.gcd(num2);
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num3 = " + num3);
// 输出结果：
// num1 = 4
// num2 = 2
// num3 = 2

abs

求出BigInteger的绝对值，不影响原来的数据

public BigInteger abs()

BigInteger num1 = new BigInteger("-4");
// 求绝对值
BigInteger num2 = num1.abs();
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
// 输出结果：
// num1 = -4
// num2 = 4

negate

求出BigInteger的相反数，不影响原来的数据

public BigInteger negate()

BigInteger num1 = new BigInteger("-4");
// 求相反数
BigInteger num2 = num1.negate();
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
// 输出结果：
// num1 = -4
// num2 = 4

max

求出两个BigInteger中的较大者

public BigInteger max(BigInteger val)

BigInteger num1 = new BigInteger("-4");
BigInteger num2 = new BigInteger("2");
// 求较大值
BigInteger num3 = num1.max(num2);
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num3 = " + num3);
// 输出：
// num1 = -4
// num2 = 2
// num3 = 2

min

求出两个BigInteger中的较小者

public BigInteger min(BigInteger val)

BigInteger num1 = new BigInteger("-4");
BigInteger num2 = new BigInteger("2");
// 求较小值
BigInteger num3 = num1.min(num2);
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
System.out.println("num3 = " + num3);
// 输出：
// num1 = -4
// num2 = 2
// num3 = -4

pow

快速幂

public BigInteger pow(int exponent)

BigInteger num1 = new BigInteger("2");
// 求2的64次方
BigInteger num2 = num1.pow(64);
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
// 输出结果：
// num1 = 2
// num2 = 18446744073709551616

modPow

快速幂求模

public BigInteger modPow(BigInteger exponent, BigInteger m)

exponent为幂，m为模

// 求2的64次方，模1000
BigInteger num1 = new BigInteger("2");
BigInteger num2 = num1.modPow(new BigInteger("64"), new BigInteger("1000"));
System.out.println("num1 = " + num1);
System.out.println("num2 = " + num2);
// 结果：
// num1 = 2
// num2 = 616