BigDecimal bignum1 = new BigDecimal("10"); 
BigDecimal bignum2 = new BigDecimal("5"); 
BigDecimal bignum3 = null; 
 
//加法 
bignum3 = bignum1.add(bignum2); 
System.out.println("和 是：" + bignum3); 
 
//减法 
bignum3 = bignum1.subtract(bignum2); 
System.out.println("差 是：" + bignum3); 
 
//乘法 
bignum3 = bignum1.multiply(bignum2); 
System.out.println("积 是：" + bignum3); 
 
//除法 
bignum3 = bignum1.divide(bignum2); 
System.out.println("商 是：" + bignum3); 

BigDecimal num1 = new BigDecimal("0"); 
BigDecimal num2 = new BigDecimal("1"); 
BigDecimal num3 = new BigDecimal("2"); 
 
BigDecimal num = new BigDecimal("1"); //用做比较的值 
 
System.out.println(num1.compareTo(num)); //小于 时，返回 -1 
System.out.println(num2.compareTo(num)); //等于 时，返回 0 
System.out.println(num3.compareTo(num)); //大于 时，返回 1 

for (BigDecimal i = new BigDecimal("0"); i.compareTo(new BigDecimal("10")) != 1; i = i.add(new BigDecimal("1"))) { 
 System.out.print(i + "\t"); 
} 

 amount.add( thisAmount );

 amount = amount.add( thisAmount );

 BigDecimal a = new BigDecimal("2.00");
 BigDecimal b = new BigDecimal("2.0");
 print(a.equals(b)); // false

 a.compareTo(b); // returns (-1 if a < b), (0 if a == b), (1 if a > b)
 a.signum(); // returns (-1 if a < 0), (0 if a == 0), (1 if a > 0)

System.out.println("=================="); 
for(int i = 0; i < 10; i ++) { 
 StringBuffer sb = new StringBuffer(); 
 sb.append("0."); 
 sb.append(i); 
 sb.append("5"); 
 BigDecimal bdx = new BigDecimal(sb.toString()); 
 System.out.println(sb + " " +bdx.setScale(1, RoundingMode.HALF_EVEN)); 
} 
 
System.out.println("=================="); 
for(int i = 0; i < 10; i ++) { 
 StringBuffer sb = new StringBuffer(); 
 sb.append("0."); 
 sb.append(i); 
 sb.append("5"); 
 BigDecimal bdx = new BigDecimal(Double.valueOf(sb.toString())); 
 System.out.println(sb + " " +bdx.setScale(1, RoundingMode.HALF_EVEN)); 
} 

==================
0.05 0.0
0.15 0.2
0.25 0.2
0.35 0.4
0.45 0.4
0.55 0.6
0.65 0.6
0.75 0.8
0.85 0.8
0.95 1.0
==================
0.05 0.1
0.15 0.1
0.25 0.2
0.35 0.3
0.45 0.5
0.55 0.6
0.65 0.7
0.75 0.8
0.85 0.8
0.95 0.9