Package org.apache.flink.util

Class Preconditions

java.lang.Object

org.apache.flink.util.Preconditions

@Internal
public final class Preconditions
extends Object

A collection of static utility methods to validate input.

This class is modelled after Google Guava's Preconditions class, and partly takes code from that class. We add this code to the Flink code base in order to reduce external dependencies.

Method Summary

Modifier and Type	Method	Description
static void	checkArgument(boolean condition)	Checks the given boolean condition, and throws an IllegalArgumentException if the condition is not met (evaluates to false).
static void	checkArgument(boolean condition, Object errorMessage)	Checks the given boolean condition, and throws an IllegalArgumentException if the condition is not met (evaluates to false).
static void	checkArgument(boolean condition, String errorMessageTemplate, Object... errorMessageArgs)	Checks the given boolean condition, and throws an IllegalArgumentException if the condition is not met (evaluates to false).
static void	checkCompletedNormally(CompletableFuture<?> future)	Ensures that future has completed normally.
static void	checkElementIndex(int index, int size)	Ensures that the given index is valid for an array, list or string of the given size.
static void	checkElementIndex(int index, int size, String errorMessage)	Ensures that the given index is valid for an array, list or string of the given size.
static <T> T	checkNotNull(T reference)	Ensures that the given object reference is not null.
static <T> T	checkNotNull(T reference, String errorMessage)	Ensures that the given object reference is not null.
static <T> T	checkNotNull(T reference, String errorMessageTemplate, Object... errorMessageArgs)	Ensures that the given object reference is not null.
static void	checkState(boolean condition)	Checks the given boolean condition, and throws an IllegalStateException if the condition is not met (evaluates to false).
static void	checkState(boolean condition, Object errorMessage)	Checks the given boolean condition, and throws an IllegalStateException if the condition is not met (evaluates to false).
static void	checkState(boolean condition, String errorMessageTemplate, Object... errorMessageArgs)	Checks the given boolean condition, and throws an IllegalStateException if the condition is not met (evaluates to false).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

checkNotNull

public static <T> T checkNotNull(@Nullable
                                 T reference)

Ensures that the given object reference is not null. Upon violation, a NullPointerException with no message is thrown.

Parameters:

reference - The object reference

Returns:

The object reference itself (generically typed).

Throws:

NullPointerException - Thrown, if the passed reference was null.

checkNotNull

public static <T> T checkNotNull(@Nullable
                                 T reference,
                                 @Nullable
                                 String errorMessage)

Ensures that the given object reference is not null. Upon violation, a NullPointerException with the given message is thrown.

Parameters:

reference - The object reference

errorMessage - The message for the NullPointerException that is thrown if the check fails.

Returns:

The object reference itself (generically typed).

Throws:

NullPointerException - Thrown, if the passed reference was null.

checkNotNull

public static <T> T checkNotNull(T reference,
                                 @Nullable
                                 String errorMessageTemplate,
                                 @Nullable
                                 Object... errorMessageArgs)

Ensures that the given object reference is not null. Upon violation, a NullPointerException with the given message is thrown.

The error message is constructed from a template and an arguments array, after a similar fashion as String.format(String, Object...), but supporting only %s as a placeholder.

Parameters:

reference - The object reference

errorMessageTemplate - The message template for the NullPointerException that is thrown if the check fails. The template substitutes its %s placeholders with the error message arguments.

errorMessageArgs - The arguments for the error message, to be inserted into the message template for the %s placeholders.

Returns:

The object reference itself (generically typed).

Throws:

NullPointerException - Thrown, if the passed reference was null.

checkArgument

public static void checkArgument(boolean condition)

Checks the given boolean condition, and throws an IllegalArgumentException if the condition is not met (evaluates to false).

Parameters:

condition - The condition to check

Throws:

IllegalArgumentException - Thrown, if the condition is violated.

checkArgument

public static void checkArgument(boolean condition,
                                 @Nullable
                                 Object errorMessage)

Checks the given boolean condition, and throws an IllegalArgumentException if the condition is not met (evaluates to false). The exception will have the given error message.

Parameters:

condition - The condition to check

errorMessage - The message for the IllegalArgumentException that is thrown if the check fails.

Throws:

IllegalArgumentException - Thrown, if the condition is violated.

checkArgument

public static void checkArgument(boolean condition,
                                 @Nullable
                                 String errorMessageTemplate,
                                 @Nullable
                                 Object... errorMessageArgs)

Checks the given boolean condition, and throws an IllegalArgumentException if the condition is not met (evaluates to false).

Parameters:

condition - The condition to check

errorMessageTemplate - The message template for the IllegalArgumentException that is thrown if the check fails. The template substitutes its %s placeholders with the error message arguments.

errorMessageArgs - The arguments for the error message, to be inserted into the message template for the %s placeholders.

Throws:

IllegalArgumentException - Thrown, if the condition is violated.

checkState

public static void checkState(boolean condition)

Checks the given boolean condition, and throws an IllegalStateException if the condition is not met (evaluates to false).

Parameters:

condition - The condition to check

Throws:

IllegalStateException - Thrown, if the condition is violated.

checkState

public static void checkState(boolean condition,
                              @Nullable
                              Object errorMessage)

Checks the given boolean condition, and throws an IllegalStateException if the condition is not met (evaluates to false). The exception will have the given error message.

Parameters:

condition - The condition to check

errorMessage - The message for the IllegalStateException that is thrown if the check fails.

Throws:

IllegalStateException - Thrown, if the condition is violated.

checkState

public static void checkState(boolean condition,
                              @Nullable
                              String errorMessageTemplate,
                              @Nullable
                              Object... errorMessageArgs)

Checks the given boolean condition, and throws an IllegalStateException if the condition is not met (evaluates to false).

Parameters:

condition - The condition to check

errorMessageTemplate - The message template for the IllegalStateException that is thrown if the check fails. The template substitutes its %s placeholders with the error message arguments.

errorMessageArgs - The arguments for the error message, to be inserted into the message template for the %s placeholders.

Throws:

IllegalStateException - Thrown, if the condition is violated.

checkElementIndex

public static void checkElementIndex(int index,
                                     int size)

Ensures that the given index is valid for an array, list or string of the given size.

Parameters:

index - index to check

size - size of the array, list or string

Throws:

IllegalArgumentException - Thrown, if size is negative.

IndexOutOfBoundsException - Thrown, if the index negative or greater than or equal to size

checkElementIndex

public static void checkElementIndex(int index,
                                     int size,
                                     @Nullable
                                     String errorMessage)

Ensures that the given index is valid for an array, list or string of the given size.

Parameters:

index - index to check

size - size of the array, list or string

errorMessage - The message for the IndexOutOfBoundsException that is thrown if the check fails.

Throws:

IllegalArgumentException - Thrown, if size is negative.

IndexOutOfBoundsException - Thrown, if the index negative or greater than or equal to size

checkCompletedNormally

public static void checkCompletedNormally(CompletableFuture<?> future)

Ensures that future has completed normally.

Throws:

IllegalStateException - Thrown, if future has not completed or it has completed exceptionally.