com.google.appengine.api.search.checkers
Class Preconditions
- java.lang.Object
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- com.google.appengine.api.search.checkers.Preconditions
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public final class Preconditions extends java.lang.Object
Simple static methods to be called at the start of your own methods to verify correct arguments and state. This allows constructs such as
to be replaced with the more compactif (count <= 0) { throw new IllegalArgumentException("must be positive: " + count); }
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 anassert
or a JUnitassertTrue
call.Note:This class is a copy of a very old version of Guava's Preconditions. Please use the current Guava version instead.
- See Also:
- "https://google.github.io/guava/releases/21.0/api/docs/com/google/common/base/Preconditions.html"
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Method Summary
All Methods Static Methods Concrete Methods 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.static void
checkState(boolean expression, java.lang.String errorMessage)
Ensures the truth of an expression involving the state of the calling instance.static void
checkState(boolean expression, java.lang.String errorMessageTemplate, java.lang.Object... errorMessageArgs)
Ensures the truth of an expression involving the state of the calling instance.
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Method Detail
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checkArgument
public static void checkArgument(boolean expression, java.lang.Object errorMessage)
Ensures the truth of an expression involving one or more parameters to the calling method.- Parameters:
expression
- a boolean expressionerrorMessage
- the exception message to use if the check fails; will be converted to a string usingString.valueOf(Object)
if not null (a null will not be converted).- Throws:
java.lang.IllegalArgumentException
- ifexpression
is false
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checkArgument
public 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.- Parameters:
expression
- a boolean expressionerrorMessageTemplate
- a template for the exception message should the check fail. The message is formed usingString.format(String, Object...)
. if not null (a null will not be converted).errorMessageArgs
- the arguments to be substituted into the message template.- Throws:
java.lang.IllegalArgumentException
- ifexpression
is false
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checkNotNull
public 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.- Parameters:
reference
- an object referenceerrorMessage
- the exception message to use if the check fails; will be converted to a string usingString.valueOf(Object)
- Returns:
- the non-null reference that was validated
- Throws:
java.lang.NullPointerException
- ifreference
is null
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checkState
public static void checkState(boolean expression, java.lang.String errorMessageTemplate, java.lang.Object... errorMessageArgs)
Ensures the truth of an expression involving the state of the calling instance.- Parameters:
expression
- a boolean expressionerrorMessageTemplate
- a template for the exception message should the check fail. The message is formed usingString.format(String, Object...)
. if not null (a null will not be converted).errorMessageArgs
- the arguments to be substituted into the message template.- Throws:
java.lang.IllegalStateException
- ifexpression
is false
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checkState
public static void checkState(boolean expression, java.lang.String errorMessage)
Ensures the truth of an expression involving the state of the calling instance.- Parameters:
expression
- a boolean expressionerrorMessage
- the exception message to use if the check fails; will be converted to a string usingString.valueOf(Object)
if not null (a null will not be converted).- Throws:
java.lang.IllegalStateException
- ifexpression
is false
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