除法
public static double div(double v1, double v2, int scale) {if (scale < 0) {throw new IllegalArgumentException("The scale must be a positive integer or zero");}BigDecimal b1 = new BigDecimal(Double.toString(v1));BigDecimal b2 = new BigDecimal(Double.toString(v2));return b1.divide(b2, scale, BigDecimal.ROUND_HALF_UP).doubleValue();
}
String转float并且保留两位小数
float allje =0;
for (int c = 0;c<alllist.size();c++){allje = allje +(Float.parseFloat(alllist.get(c).price)*alllist.get(c).buynum);
}
DecimalFormat fnum = new DecimalFormat("##0.00");
String dd = fnum.format(allje);
/** *Math.sqrt()//计算平方根*Math.cbrt()//计算立方根*Math.pow(a, b)//计算a的b次方*Math.max( , );//计算最大值*Math.min( , );//计算最小值*/ System.out.println(Math.sqrt(16)); //4.0 System.out.println(Math.cbrt(8)); //2.0System.out.println(Math.pow(3,2)); //9.0System.out.println(Math.max(2.3,4.5));//4.5System.out.println(Math.min(2.3,4.5));//2.3 /** * abs求绝对值 */ System.out.println(Math.abs(-10.4)); //10.4 System.out.println(Math.abs(10.1)); //10.1 /** * ceil天花板的意思，就是返回大的值。小数不为0，整数 加 1*/ System.out.println(Math.ceil(0.00)); //0.0
System.out.println(Math.ceil(10.001)); //11
/** * floor地板的意思，就是返回小的值 。小数不为0，整数 减 1*/ System.out.println(Math.floor(-0.7)); //-1.0
System.out.println(Math.floor(0.0)); //0.0
System.out.println(Math.random()); //小于1大于0的double类型的数
0.5041101701502628
四舍五入
System.out.println(Math.round(10.1)); //10
System.out.println(Math.round(10.7)); //11
