Java double 加、减、乘、除详解编程语言

import org.junit.Test; 
import java.math.BigDecimal; 
import java.math.MathContext; 
/** 
* @author ceshi 
* @Title: BigDecimalUtil 
* @ProjectName BigDecimalUtil 
* @Description: TODO 
* @date 2018/7/2719:30 
*/ 
public class BigDecimalUtil { 
@Test 
public void test(){ 
System.out.println(add(0.02,0.03)); 
System.out.println(subtraction(0.05,0.03,2)); 
System.out.println(multiplication(0.2,0.3)); 
System.out.println(division(0.02,0.03,2)); 
System.out.println(divisionRounding(0.5,0)); 
} 
/** 
* double加法 
* @param a 
* @param b 
* @return 
*/ 
public double add(double a, double b) { 
BigDecimal b1=new BigDecimal(a); 
BigDecimal b2 = new BigDecimal(b); 
return b1.add(b2).doubleValue(); 
} 
/** 
* double减法 
* @param a 
* @param b 
* @param setPrecision 设置精度 
* @return 
*/ 
public static double subtraction(double a, double b,int setPrecision) { 
BigDecimal b1 = new BigDecimal(a); 
BigDecimal b2 = new BigDecimal(b); 
return b1.subtract(b2,new MathContext(setPrecision)).doubleValue(); 
} 
/** 
* double乘法 结果保留两位小数 
* @param a 
* @param b 
* @return 
*/ 
public static double multiplication(double a, double b) { 
BigDecimal b1 = new BigDecimal(a); 
BigDecimal b2 = new BigDecimal(b); 
return b1.multiply(b2).doubleValue(); 
} 
/** 
* double除法 
* @param a 
* @param b 
* @param accurate 结果保留位数 
* @return 
*/ 
public static double division(double a, double b,int accurate) { 
if (accurate < 0) { 
throw new RuntimeException("精确度必须是正整数或零"); 
} 
BigDecimal b1 = new BigDecimal(a); 
BigDecimal b2 = new BigDecimal(b); 
return b1.divide(b2, accurate, BigDecimal.ROUND_HALF_UP).doubleValue(); 
} 
/** 
* double除法 四舍五入 
* @param a 
* @param scale accurate 小数点后留几位 
* @return 
*/ 
public static double divisionRounding(double a, int scale) { 
if (scale < 0) { 
throw new RuntimeException("精确度必须是正整数或零"); 
} 
BigDecimal b = new BigDecimal(a); 
BigDecimal one = new BigDecimal("1"); 
return b.divide(one, scale, BigDecimal.ROUND_HALF_UP).doubleValue(); 
} 
}