package com.atguigu.test12;import java.math.BigDecimal;import java.math.BigInteger;import org.junit.Test;/* * 数学相关的常用类: * 1、java.lang.Math类 * * 2、java.math包 * BigInteger * BigDecimal * * * 面试题:int ,Integer, BigInteger什么区别?
*/public class TestMath { @Test public void test4(){ BigDecimal big1 = new BigDecimal("72.345678912345678912345678"); BigDecimal big2 = new BigDecimal("4.2345678912345678912345678"); System.out.println("和:" + big1.add(big2)); System.out.println("减:" + big1.subtract(big2)); System.out.println("乘:" + big1.multiply(big2));// System.out.println("除:" + big1.divide(big2));//如果除不尽,会报异常 //divide(BigDecimal divisor, int scale, int roundingMode) System.out.println("除:" + big1.divide(big2, 10, BigDecimal.ROUND_CEILING)); System.out.println("余:" + big1.remainder(big2)); } @Test public void test3(){// long big = 12345678912345678912345678L; BigInteger big1 = new BigInteger("72345678912345678912345678"); BigInteger big2 = new BigInteger("42345678912345678912345678"); System.out.println("和:" + big1.add(big2)); System.out.println("减:" + big1.subtract(big2)); System.out.println("乘:" + big1.multiply(big2)); System.out.println("除:" + big1.divide(big2)); System.out.println("余:" + big1.remainder(big2)); } @Test public void test2(){ System.out.println(Math.ceil(2.1));//进一法 System.out.println(Math.floor(2.1));//退一法 System.out.println(Math.round(2.1));//四舍五入 System.out.println(); System.out.println(Math.ceil(2.6));//进一法 System.out.println(Math.floor(2.6));//退一法 System.out.println(Math.round(2.6));//四舍五入 System.out.println(); System.out.println(Math.ceil(-2.1));//进一法 System.out.println(Math.floor(-2.1));//退一法 System.out.println(Math.round(-2.1));//四舍五入 System.out.println(); System.out.println(Math.ceil(-2.6));//进一法 System.out.println(Math.floor(-2.6));//退一法 System.out.println(Math.round(-2.6));//四舍五入 System.out.println(); } @Test public void test1(){ System.out.println(Math.PI); System.out.println(Math.sqrt(9)); System.out.println(Math.pow(2, 8));//2的8次方 System.out.println(Math.max(5, 9)); System.out.println(Math.min(3, 9)); }}