public final class Preconditions
extends java.lang.Object
if (count <= 0) {
throw new IllegalArgumentException("must be positive: " + count);
}
to be replaced with the more compact
checkArgument(count > 0, "must be positive: %s", count);
Note that the sense of the expression is inverted; with Preconditions you declare what you expect to be true, just as you
do with an
assert or a JUnit assertTrue call.
| Modifier and Type | Method and Description |
|---|---|
static void |
checkArgument(boolean expression,
java.lang.Object errorMessage)
Ensures the truth of an expression involving one or more parameters to the
calling method.
|
static void |
checkArgument(boolean expression,
java.lang.String errorMessageTemplate,
java.lang.Object... errorMessageArgs)
Ensures the truth of an expression involving one or more parameters to the
calling method.
|
static <T> T |
checkNotNull(T reference,
java.lang.Object errorMessage)
Ensures that an object reference passed as a parameter to the calling
method is not null.
|
public static void checkArgument(boolean expression,
java.lang.Object errorMessage)
expression - a boolean expressionerrorMessage - the exception message to use if the check fails; will
be converted to a string using String.valueOf(Object) if
not null (a null will not be converted).java.lang.IllegalArgumentException - if expression is falsepublic static void checkArgument(boolean expression,
java.lang.String errorMessageTemplate,
java.lang.Object... errorMessageArgs)
expression - a boolean expressionerrorMessageTemplate - a template for the exception message should the
check fail. The message is formed using String.format(String, Object...).
if not null (a null will not be converted).errorMessageArgs - the arguments to be substituted into the message
template.java.lang.IllegalArgumentException - if expression is falsepublic static <T> T checkNotNull(T reference,
java.lang.Object errorMessage)
reference - an object referenceerrorMessage - the exception message to use if the check fails; will
be converted to a string using String.valueOf(Object)java.lang.NullPointerException - if reference is null