JAVA biginteger类bigdecimal类的使用示例学习

package com.fenxiangbe.regex;
import java.math.BigInteger;
public class Demo_BigInteger {
	
	public static void main(String[] args) {
		BigInteger bi1 = new BigInteger("100");
		BigInteger bi2 = new BigInteger("2");
		System.out.println(bi1.add(bi2));//bi1+bi2=102
		System.out.println(bi1.subtract(bi2));//bi1-bi2=98
		System.out.println(bi1.multiply(bi2));//bi1*bi2=200
		System.out.println(bi1.divide(bi2));//bi1/bi2=50
		BigInteger[] arr = bi1.divideAndRemainder(bi2);// bi1/bi2=50....0
		for (int i = 0; i < arr.length; i++) {
			System.out.println(arr[i]);
		}
	}
}

package com.fenxiangbe.regex;
import java.math.BigDecimal;
public class Demo_BigDecimal {
	
	public static void main(String[] args) {
		BigDecimal bd1 = new BigDecimal(2.0);
		BigDecimal bd2 = new BigDecimal(1.1);
		System.out.println(bd1.subtract(bd2));//不推荐 不够精确，2.0-1.1=0.9，但是运行结果却是0.899999999999999911182158029987476766109466552734375
		BigDecimal bd3 = new BigDecimal("2.0");
		BigDecimal bd4 = new BigDecimal("1.1");
		System.err.println(bd3.subtract(bd4));//推荐，转换成字符串进行运算 就能精确算出值2.0-1.1=0.9
		//通过value of方法也可以运算
		BigDecimal bd5 = BigDecimal.valueOf(2.0);
		BigDecimal bd6 = BigDecimal.valueOf(1.1);
		System.out.println(bd5.subtract(bd6));//推荐 ，用这两种方法都可以
	}
}