Use setRoundingMode
, set the RoundingMode
explicitly to handle your issue with the half-even round, then use the format pattern for your required output.
Example:
DecimalFormat df = new DecimalFormat("#.####");
df.setRoundingMode(RoundingMode.CEILING);
for (Number n : Arrays.asList(12, 123.12345, 0.23, 0.1, 2341234.212431324)) {
Double d = n.doubleValue();
System.out.println(df.format(d));
}
gives the output:
12
123.1235
0.23
0.1
2341234.2125
EDIT: The original answer does not address the accuracy of the double values. That is fine if you don't care much whether it rounds up or down. But if you want accurate rounding, then you need to take the expected accuracy of the values into account. Floating point values have a binary representation internally. That means that a value like 2.7735 does not actually have that exact value internally. It can be slightly larger or slightly smaller. If the internal value is slightly smaller, then it will not round up to 2.7740. To remedy that situation, you need to be aware of the accuracy of the values that you are working with, and add or subtract that value before rounding. For example, when you know that your values are accurate up to 6 digits, then to round half-way values up, add that accuracy to the value:
Double d = n.doubleValue() + 1e-6;
To round down, subtract the accuracy.
The docs for java.io.Serializable
are probably about as good an explanation as you'll get:
The serialization runtime associates with each serializable class a version number, called a serialVersionUID
, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization. If the receiver has loaded a class for the object that has a different serialVersionUID
than that of the corresponding sender's class, then deserialization will result in an
InvalidClassException
. A serializable class can declare its own serialVersionUID
explicitly by declaring a field named serialVersionUID
that must be static, final, and of type long
:
ANY-ACCESS-MODIFIER static final long serialVersionUID = 42L;
If a serializable class does not explicitly declare a serialVersionUID
, then the serialization runtime will calculate a default serialVersionUID
value for that class based on various aspects of the class, as described in the Java(TM) Object Serialization Specification. However, it is strongly recommended that all serializable classes explicitly declare serialVersionUID
values, since the default serialVersionUID
computation is highly sensitive to class details that may vary depending on compiler implementations, and can thus result in unexpected InvalidClassExceptions
during deserialization. Therefore, to guarantee a consistent serialVersionUID
value across different java compiler implementations, a serializable class must declare an explicit serialVersionUID
value. It is also strongly advised that explicit serialVersionUID
declarations use the private modifier where possible, since such declarations apply only to the immediately declaring class — serialVersionUID
fields are not useful as inherited members.
Best Answer
The
@EJB
is used to inject EJB's only and is available for quite some time now.@Inject
can inject any managed bean and is a part of the new CDI specification (since Java EE 6).In simple cases you can simply change
@EJB
to@Inject
. In more advanced cases (e.g. when you heavily depend on@EJB
's attributes likebeanName
,lookup
orbeanInterface
) than in order to use@Inject
you would need to define a@Producer
field or method.These resources might be helpful to understand the differences between
@EJB
and@Produces
and how to get the best of them:Antonio Goncalves' blog:
CDI Part I
CDI Part II
CDI Part III
JBoss Weld documentation:
CDI and the Java EE ecosystem
StackOverflow:
Inject @EJB bean based on conditions