Why do bean validation Min/Max constraints not support the double type?

It is because of rounding. But not because of the problem that a double is may not correct enough to express the number you want. It is more that the annotation value (of Min and Max) is of type long, so it can not express any number with decimal places. On the other hand you can not use a double to express exact all numbers that a long can express.

So the API designers had to decide for one of the two ways (long or double)

Use the @DecimalMin annotation. You will need to pass a literal String value, because the attrubute value must be constant (String.valueOf(- Math.PI)) doesn't work. It works to validate Double attributes.

@DecimalMin(value = "0.01", message = "Your message...")
private Double longitude;