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java.lang.Objectcom.google.appengine.api.search.checkers.Preconditions
public final class Preconditions
Simple static methods to be called at the start of your own methods to verify correct arguments and state. This allows constructs such as
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.
| Method Summary | ||
|---|---|---|
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
|
checkNotNull(T reference,
java.lang.Object errorMessage)
Ensures that an object reference passed as a parameter to the calling method is not null. |
|
| Methods inherited from class java.lang.Object |
|---|
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Method Detail |
|---|
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 false
public 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 false
public 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
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