保留小数点位数和格式

JS 中

1. double运算
c = parseFloat(a) + parseFloat(b))

2. 四舍五入，保留两位小数
c = c.toFixed(2);

3. 去掉小数点后面多余的0
c = c.toFixed(2)*100/100;


JAVA中

//四舍五入，保留指定小数位
public static Double roundDouble(Object obj,
int scale){

double d = 0;
try{
d = Double.parseDouble(obj.toString().replaceAll(",",
""));
} catch (Exception e) {
d = 0;
}

//四舍五入，保留两位小数
BigDecimal bd = new BigDecimal(d);
bd = bd.setScale(scale, BigDecimal.ROUND_HALF_UP);
d = bd.doubleValue();

return d;
}


//转成字符串，去掉科学计数法
public static String roundFormat(Object obj){
String str = "0";
try{
Double d = Double.parseDouble(obj.toString().replaceAll(",",
""));

//四舍五入，保留两位小数
BigDecimal bd = new BigDecimal(d);
bd = bd.setScale(2, BigDecimal.ROUND_HALF_UP);
d = bd.doubleValue();

//去除科学计数法
DecimalFormat df = new DecimalFormat("#.##");
str = df.format(d);

} catch (Exception e) {
str = "0";
}


return str;
}


//除法
public static Double divideRound(Double a, Double b){
try {
if (b == 0) {
return 0.0;
} else {
BigDecimal bd = new BigDecimal(a/b);
bd = bd.setScale(2, BigDecimal.ROUND_HALF_UP);
double d = bd.doubleValue();
bd = null;
return d;
}
} catch (Exception e) {
return 0.0;
}
}

//四舍五入，保留指定小数位
public static Double roundDouble(Object obj, int scale){
		
		double d = 0;
	 	try{
			d  = Double.parseDouble(obj.toString().replaceAll(",", ""));
		  } catch (Exception e) {
		  	d = 0;
		  }

		//四舍五入，保留两位小数
		BigDecimal bd = new BigDecimal(d);  
		bd = bd.setScale(scale, BigDecimal.ROUND_HALF_UP);
		d = bd.doubleValue(); 
		  
		return d;
	}


//转成字符串，去掉科学计数法
public static String roundFormat(Object obj){
	 	String str = "0";
	 	try{
			Double d  = Double.parseDouble(obj.toString().replaceAll(",", ""));
			 
			//四舍五入，保留两位小数
			BigDecimal bd = new BigDecimal(d);  
			bd = bd.setScale(2, BigDecimal.ROUND_HALF_UP);
			d = bd.doubleValue(); 
			      
			//去除科学计数法 
			DecimalFormat df = new DecimalFormat("#.##"); 
			str = df.format(d);			
			
		  } catch (Exception e) {
		  		str = "0";
		  }
		  
		  
		return str;
	 }


//除法
public static Double divideRound(Double a, Double b){
		try {
			if (b == 0) {
				return 0.0;
			} else {
				BigDecimal bd = new BigDecimal(a/b);  
		        bd = bd.setScale(2, BigDecimal.ROUND_HALF_UP);  
		        double d = bd.doubleValue();  
		        bd = null;  
		        return d;  
			}
		} catch (Exception e) {
	  		return 0.0;
	  	}
	}