百分比

public static void main(String [] args){ 
	double a = 2 ; 
	double b = 345 ; 
	double result = 0 ; 
	
	BigDecimal b1 = new BigDecimal(a); 
	BigDecimal b3 = new BigDecimal(b); 
	// b1除以 b3
	result = b1.divide(b3, 7, BigDecimal.ROUND_HALF_UP).doubleValue();  // * 100.0
	
	//discount = String.valueOf(result) + "%";  
	System.out.println(result);
	DecimalFormat df = new DecimalFormat("#0.00");
	System.out.println(df.format(result * 100 ));
	/**
	0.0057971
	0.58
	 */
 
}