/** * 提供了(相對)精確的除法運算,當發生除不儘的情況時,由scale參數指定 * 精度,以後的數字四捨五入 * @param args */ 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(); }
/** * 提供了精確的小數位四捨五入處理 * @param args */
public static double round(double v, int scale) { if (scale<0) { throw new IllegalArgumentException("The scale must be a positive integer or zero"); } BigDecimal b = new BigDecimal(Double.toString(v)); BigDecimal one = new BigDecimal("1"); return b.divide(one, scale, BigDecimal.ROUND_HALF_DOWN).doubleValue(); } public static void main(String[] args) { System.out.println(add(1.2321231, 3.7865765)); System.out.println(sub(6.4523423, 1.2321231)); System.out.println(mul(6.4523423, 3.7865765)); System.out.println(div(6.4523423, 3.7865765, 5)); System.out.println(round(3.7865765, 5)); } }
import java.text.*; class Test2 { public Test2() { double a=10000;//要用double型,要不a/b永远得0; double b=20000; NumberFormat nbf=NumberFormat.getInstance();//新建一个格式化器对象 nbf.setMinimumFractionDigits(2);//设置最小保留两位小数 nbf.setMaximumFractionDigits(2);//设置最大保留两位小数 String c = nbf.format(a/b);//将a/b格式化后的值赋给c,注意是String型 System.out.println(c); }
public static void main(String[] args) { Test2 test2 = new Test2(); } }
class Test2
{
public Test2()
{
double a=10000;//要用double型,要不a/b永远得0;
double b=20000;
NumberFormat nbf=NumberFormat.getInstance();
nbf.setMinimumFractionDigits(2);
String c = nbf.format(a/b);
System.out.println(c);
}
public static void main(String[] args)
{
Test2 test2 = new Test2();
}
}
* 提供精確的加法運算
* @param args
*/
public static double add(double v1, double v2) {
BigDecimal b1 = new BigDecimal(Double.toString(v1));
BigDecimal b2 = new BigDecimal(Double.toString(v2));
return b1.add(b2).doubleValue();
} /**
* 提供了精確的減法運算
*
* @param args
*/
public static double sub(double v1, double v2) {
BigDecimal b1 = new BigDecimal(Double.toString(v1));
BigDecimal b2 = new BigDecimal(Double.toString(v2));
return b1.subtract(b2).doubleValue();
}
/**
* 提供了精確的乘法運算
* @param args
*/
public static double mul(double v1, double v2) {
BigDecimal b1 = new BigDecimal(Double.toString(v1));
BigDecimal b2 = new BigDecimal(Double.toString(v2));
return b1.multiply(b2).doubleValue();
}
/**
* 提供了(相對)精確的除法運算,當發生除不儘的情況時,精確到
* 小數點以後110位
* @param args
*/
public static double div(double v1, double v2) {
return div(v1, v2, DEF_DIV_SCALE);
}
/**
* 提供了(相對)精確的除法運算,當發生除不儘的情況時,由scale參數指定
* 精度,以後的數字四捨五入
* @param args
*/
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();
}
/**
* 提供了精確的小數位四捨五入處理
* @param args
*/
public static double round(double v, int scale) {
if (scale<0) {
throw new IllegalArgumentException("The scale must be a positive integer or zero");
}
BigDecimal b = new BigDecimal(Double.toString(v));
BigDecimal one = new BigDecimal("1");
return b.divide(one, scale, BigDecimal.ROUND_HALF_DOWN).doubleValue();
} public static void main(String[] args) {
System.out.println(add(1.2321231, 3.7865765));
System.out.println(sub(6.4523423, 1.2321231));
System.out.println(mul(6.4523423, 3.7865765));
System.out.println(div(6.4523423, 3.7865765, 5));
System.out.println(round(3.7865765, 5));
}
}
class Test2
{
public Test2()
{
double a=10000;//要用double型,要不a/b永远得0;
double b=20000;
NumberFormat nbf=NumberFormat.getInstance();//新建一个格式化器对象
nbf.setMinimumFractionDigits(2);//设置最小保留两位小数
nbf.setMaximumFractionDigits(2);//设置最大保留两位小数
String c = nbf.format(a/b);//将a/b格式化后的值赋给c,注意是String型
System.out.println(c);
}
public static void main(String[] args)
{
Test2 test2 = new Test2();
}
}