Question

I have some constants f.e.:

BigDecimal ceiling1 = new BigDecimal(5);
BigDecimal ceiling2 = new BigDecimal(10);
BigDecimal ceiling3 = new BigDecimal(20);

BigDecimal rate1 = new BigDecimal(0.01);
BigDecimal rate2 = new BigDecimal(0.02);
BigDecimal rate3 = new BigDecimal(0.04);
BigDecimal rate4 = new BigDecimal(0.09);

Now based on a parameter f.e.:

BigDecimal arg = new BigDecimal(6);

I want to retrieve the right rate which is based on this if structure (simplified):

if(arg <= ceiling1) {
   rate = rate1;
}else if(arg <= ceiling2) {
   rate = rate2;
} else if (arg <= ceiling3) {
   rate = rate3;
}else rate = rate4;

So in my example rate should be rate2

But I’m wondering if someone knows a better way to implement this, instead of a bunch of ifs.

Any pointers are welcome!

PS: I know my code isn’t 100% right, just wanted to show the idea

Answer 1

You can store your ceilings as keys in a TreeMap and your rates as values. Then use floorEntry and see also here.

final TreeMap<BigDecimal, BigDecimal> rates = new TreeMap<BigDecimal, BigDecimal>();
rates.put(new BigDecimal(0), new BigDecimal(0.01));
rates.put(new BigDecimal(5), new BigDecimal(0.02));
rates.put(new BigDecimal(10), new BigDecimal(0.04));
rates.put(new BigDecimal(20), new BigDecimal(0.09));

System.out.println(rates.floorEntry(new BigDecimal(0)).getValue());
System.out.println(rates.floorEntry(new BigDecimal(6)).getValue());
System.out.println(rates.floorEntry(new BigDecimal(10)).getValue());
System.out.println(rates.floorEntry(new BigDecimal(100)).getValue());

Test: http://ideone.com/VrucK. You may want to use a different representation as you can see in the test it looks ugly(Like Integers for the ceiling). Btw the ugly output comes from the fact that 0.01 is a double which does funny things with decimal representations.

Edit: Suggested cleanup.