数字的舍入

package com.jdk7.chapter3;

import java.math.BigDecimal;

public class Round {
    //调用java.util.Math进行四舍五入取整
    public static long getRoundMath(double dou){
        return Math.round(dou);
    }
    
    //调用java.math.BigDecimal进行不同类别的舍入
    public static BigDecimal getRoundBigDecimal(double dou, int point, int type){
        BigDecimal bd = new BigDecimal(dou);
        return bd.setScale(point, type);
    }
    
    /**
     * 在BigDecimal类中定义了不同舍入方式的值如下：
     * public final static int ROUND_UP =           0;        //远离0的舍入
     * public final static int ROUND_DOWN =         1;        //接近0的舍入
     * public final static int ROUND_CEILING =      2;        //接近正无穷大的舍入
     * public final static int ROUND_FLOOR =        3;        //接近负无穷大的舍入
     * public final static int ROUND_HALF_UP =      4;        //四舍五入
     * public final static int ROUND_HALF_DOWN =    5;        //向最接近的数字舍入，如果与两个相邻的数字相等，则为ROUND_DOWN模式
     * public final static int ROUND_HALF_EVEN =    6;        //向最接近的数字舍入，如果与两个相邻的数字相等，则向相邻的偶数舍入
     * public final static int ROUND_UNNECESSARY =  7;
     * 
     * @param args
     */
    public static void main(String[] args) {
        double dou = 345.987;
        System.out.println(getRoundMath(dou));
        System.out.println(getRoundBigDecimal(dou,0,0));
        System.out.println(getRoundBigDecimal(dou,0,1));
        System.out.println(getRoundBigDecimal(dou,0,2));
        System.out.println(getRoundBigDecimal(dou,0,3));
        System.out.println(getRoundBigDecimal(dou,0,4));
        System.out.println(getRoundBigDecimal(dou,0,5));
        System.out.println(getRoundBigDecimal(dou,0,6));
    }
}

执行结果：
346
346
345
346
345
346
346
346