java取整和java四舍五入方法

来源：互联网发布：人工智能股票代码编辑：程序博客网时间：2024/05/01 14:04
转自http://blog.csdn.net/kankan_summer/article/details/5744576
文章出自http://www.cujava.com
import java.math.BigDecimal;  import java.text.DecimalFormat;  public class TestGetInt{    public static void main(String[] args){      double i=2, j=2.1, k=2.5, m=2.9;      System.out.println("舍掉小数取整:Math.floor(2)=" + (int)Math.floor(i));      System.out.println("舍掉小数取整:Math.floor(2.1)=" + (int)Math.floor(j));      System.out.println("舍掉小数取整:Math.floor(2.5)=" + (int)Math.floor(k));      System.out.println("舍掉小数取整:Math.floor(2.9)=" + (int)Math.floor(m));                                                                                       /* 这段被注释的代码不能正确的实现四舍五入取整     System.out.println("四舍五入取整:Math.rint(2)=" + (int)Math.rint(i));     System.out.println("四舍五入取整:Math.rint(2.1)=" + (int)Math.rint(j));     System.out.println("四舍五入取整:Math.rint(2.5)=" + (int)Math.rint(k));     System.out.println("四舍五入取整:Math.rint(2.9)=" + (int)Math.rint(m));         System.out.println("四舍五入取整:(2)=" + new DecimalFormat("0").format(i));     System.out.println("四舍五入取整:(2.1)=" + new DecimalFormat("0").format(i));     System.out.println("四舍五入取整:(2.5)=" + new DecimalFormat("0").format(i));     System.out.println("四舍五入取整:(2.9)=" + new DecimalFormat("0").format(i));     */           System.out.println("四舍五入取整:(2)=" + new BigDecimal("2").setScale(0, BigDecimal.ROUND_HALF_UP));      System.out.println("四舍五入取整:(2.1)=" + new BigDecimal("2.1").setScale(0, BigDecimal.ROUND_HALF_UP));      System.out.println("四舍五入取整:(2.5)=" + new BigDecimal("2.5").setScale(0, BigDecimal.ROUND_HALF_UP));      System.out.println("四舍五入取整:(2.9)=" + new BigDecimal("2.9").setScale(0, BigDecimal.ROUND_HALF_UP));      System.out.println("凑整:Math.ceil(2)=" + (int)Math.ceil(i));      System.out.println("凑整:Math.ceil(2.1)=" + (int)Math.ceil(j));      System.out.println("凑整:Math.ceil(2.5)=" + (int)Math.ceil(k));      System.out.println("凑整:Math.ceil(2.9)=" + (int)Math.ceil(m));      System.out.println("舍掉小数取整:Math.floor(-2)=" + (int)Math.floor(-i));      System.out.println("舍掉小数取整:Math.floor(-2.1)=" + (int)Math.floor(-j));      System.out.println("舍掉小数取整:Math.floor(-2.5)=" + (int)Math.floor(-k));      System.out.println("舍掉小数取整:Math.floor(-2.9)=" + (int)Math.floor(-m));           System.out.println("四舍五入取整:(-2)=" + new BigDecimal("-2").setScale(0, BigDecimal.ROUND_HALF_UP));      System.out.println("四舍五入取整:(-2.1)=" + new BigDecimal("-2.1").setScale(0, BigDecimal.ROUND_HALF_UP));      System.out.println("四舍五入取整:(-2.5)=" + new BigDecimal("-2.5").setScale(0, BigDecimal.ROUND_HALF_UP));      System.out.println("四舍五入取整:(-2.9)=" + new BigDecimal("-2.9").setScale(0, BigDecimal.ROUND_HALF_UP));      System.out.println("凑整:Math.ceil(-2)=" + (int)Math.ceil(-i));      System.out.println("凑整:Math.ceil(-2.1)=" + (int)Math.ceil(-j));      System.out.println("凑整:Math.ceil(-2.5)=" + (int)Math.ceil(-k));      System.out.println("凑整:Math.ceil(-2.9)=" + (int)Math.ceil(-m));      }  }    /* Output: 舍掉小数取整:Math.floor(2)=2 舍掉小数取整:Math.floor(2.1)=2 舍掉小数取整:Math.floor(2.5)=2 舍掉小数取整:Math.floor(2.9)=2 四舍五入取整:(2)=2 四舍五入取整:(2.1)=2 四舍五入取整:(2.5)=3 四舍五入取整:(2.9)=3 凑整:Math.ceil(2)=2 凑整:Math.ceil(2.1)=3 凑整:Math.ceil(2.5)=3 凑整:Math.ceil(2.9)=3 舍掉小数取整:Math.floor(-2)=-2 舍掉小数取整:Math.floor(-2.1)=-3 舍掉小数取整:Math.floor(-2.5)=-3 舍掉小数取整:Math.floor(-2.9)=-3 四舍五入取整:(-2)=-2 四舍五入取整:(-2.1)=-2 四舍五入取整:(-2.5)=-3 四舍五入取整:(-2.9)=-3 凑整:Math.ceil(-2)=-2 凑整:Math.ceil(-2.1)=-2 凑整:Math.ceil(-2.5)=-2 凑整:Math.ceil(-2.9)=-2 *///:~
0 0