java获取小数位数 java获取小数的整数部分

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));

                                                                                 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)); 


    } 


}