Package com.android.internal.util

Class Preconditions

java.lang.Object

com.android.internal.util.Preconditions

public class Preconditions
extends Object

Simple static methods to be called at the start of your own methods to verify correct arguments and state.

Constructor Summary

Constructors

Constructor	Description
Preconditions()

Method Summary

Modifier and Type	Method	Description
static void	checkArgument(boolean expression)
static float	checkArgumentFinite(float value, String valueName)	Ensures that the argument floating point value is a finite number.
static float	checkArgumentInRange(float value, float lower, float upper, String valueName)	Ensures that the argument floating point value is within the inclusive range.
static int	checkArgumentInRange(int value, int lower, int upper, String valueName)	Ensures that the argument int value is within the inclusive range.
static int	checkArgumentNonnegative(int value, String errorMessage)	Ensures that that the argument numeric value is non-negative.
static long	checkArgumentNonnegative(long value, String errorMessage)	Ensures that that the argument numeric value is non-negative.
static int	checkArgumentPositive(int value, String errorMessage)	Ensures that that the argument numeric value is positive.
static float[]	checkArrayElementsInRange(float[] value, float lower, float upper, String valueName)	Ensures that all elements in the argument floating point array are within the inclusive range
static <T> T[]	checkArrayElementsNotNull(T[] value, String valueName)	Ensures that the array is not null, and none of its elements are null.
static <T> Collection<T>	checkCollectionElementsNotNull(Collection<T> value, String valueName)	Ensures that the Collection is not null, and none of its elements are null.
static <T> Collection<T>	checkCollectionNotEmpty(Collection<T> value, String valueName)	Ensures that the Collection is not null, and contains at least one element.
static void	checkFlagsArgument(int requestedFlags, int allowedFlags)	Check the requested flags, throwing if any requested flags are outside the allowed set.
static <T> T	checkNotNull(T reference)	Ensures that an object reference passed as a parameter to the calling method is not null.
static <T> T	checkNotNull(T reference, Object errorMessage)	Ensures that an object reference passed as a parameter to the calling method is not null.
static void	checkState(boolean expression)	Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters to the calling method.

Methods inherited from class java.lang.Object

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

Constructor Detail

Preconditions

public Preconditions()

Method Detail

checkArgument

public static void checkArgument(boolean expression)

checkNotNull

public static <T> T checkNotNull(T reference)

Ensures that an object reference passed as a parameter to the calling method is not null.

Parameters:

reference - an object reference

Returns:

the non-null reference that was validated

Throws:

NullPointerException - if reference is null

checkNotNull

public static <T> T checkNotNull(T reference,
                                 Object errorMessage)

Ensures that an object reference passed as a parameter to the calling method is not null.

Parameters:

reference - an object reference

errorMessage - the exception message to use if the check fails; will be converted to a string using String.valueOf(Object)

Returns:

the non-null reference that was validated

Throws:

NullPointerException - if reference is null

checkState

public static void checkState(boolean expression)

Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters to the calling method.

Parameters:

expression - a boolean expression

Throws:

IllegalStateException - if expression is false

checkFlagsArgument

public static void checkFlagsArgument(int requestedFlags,
                                      int allowedFlags)

Check the requested flags, throwing if any requested flags are outside the allowed set.

checkArgumentNonnegative

public static int checkArgumentNonnegative(int value,
                                           String errorMessage)

Ensures that that the argument numeric value is non-negative.

Parameters:

value - a numeric int value

errorMessage - the exception message to use if the check fails

Returns:

the validated numeric value

Throws:

IllegalArgumentException - if value was negative

checkArgumentNonnegative

public static long checkArgumentNonnegative(long value,
                                            String errorMessage)

Ensures that that the argument numeric value is non-negative.

Parameters:

value - a numeric long value

errorMessage - the exception message to use if the check fails

Returns:

the validated numeric value

Throws:

IllegalArgumentException - if value was negative

checkArgumentPositive

public static int checkArgumentPositive(int value,
                                        String errorMessage)

Ensures that that the argument numeric value is positive.

Parameters:

value - a numeric int value

errorMessage - the exception message to use if the check fails

Returns:

the validated numeric value

Throws:

IllegalArgumentException - if value was not positive

checkArgumentFinite

public static float checkArgumentFinite(float value,
                                        String valueName)

Ensures that the argument floating point value is a finite number.

A finite number is defined to be both representable (that is, not NaN) and not infinite (that is neither positive or negative infinity).

Parameters:

value - a floating point value

valueName - the name of the argument to use if the check fails

Returns:

the validated floating point value

Throws:

IllegalArgumentException - if value was not finite

checkArgumentInRange

public static float checkArgumentInRange(float value,
                                         float lower,
                                         float upper,
                                         String valueName)

Ensures that the argument floating point value is within the inclusive range.

While this can be used to range check against +/- infinity, note that all NaN numbers will always be out of range.

Parameters:

value - a floating point value

lower - the lower endpoint of the inclusive range

upper - the upper endpoint of the inclusive range

valueName - the name of the argument to use if the check fails

Returns:

the validated floating point value

Throws:

IllegalArgumentException - if value was not within the range

checkArgumentInRange

public static int checkArgumentInRange(int value,
                                       int lower,
                                       int upper,
                                       String valueName)

Ensures that the argument int value is within the inclusive range.

Parameters:

value - a int value

lower - the lower endpoint of the inclusive range

upper - the upper endpoint of the inclusive range

valueName - the name of the argument to use if the check fails

Returns:

the validated int value

Throws:

IllegalArgumentException - if value was not within the range

checkArrayElementsNotNull

public static <T> T[] checkArrayElementsNotNull(T[] value,
                                                String valueName)

Ensures that the array is not null, and none of its elements are null.

Parameters:

value - an array of boxed objects

valueName - the name of the argument to use if the check fails

Returns:

the validated array

Throws:

NullPointerException - if the value or any of its elements were null

checkCollectionElementsNotNull

public static <T> Collection<T> checkCollectionElementsNotNull(Collection<T> value,
                                                               String valueName)

Ensures that the Collection is not null, and none of its elements are null.

Parameters:

value - a Collection of boxed objects

valueName - the name of the argument to use if the check fails

Returns:

the validated Collection

Throws:

NullPointerException - if the value or any of its elements were null

checkCollectionNotEmpty

public static <T> Collection<T> checkCollectionNotEmpty(Collection<T> value,
                                                        String valueName)

Ensures that the Collection is not null, and contains at least one element.

Parameters:

value - a Collection of boxed elements.

valueName - the name of the argument to use if the check fails.

Returns:

the validated Collection

Throws:

NullPointerException - if the value was null

IllegalArgumentException - if the value was empty

checkArrayElementsInRange

public static float[] checkArrayElementsInRange(float[] value,
                                                float lower,
                                                float upper,
                                                String valueName)

Ensures that all elements in the argument floating point array are within the inclusive range

While this can be used to range check against +/- infinity, note that all NaN numbers will always be out of range.

Parameters:

value - a floating point array of values

lower - the lower endpoint of the inclusive range

upper - the upper endpoint of the inclusive range

valueName - the name of the argument to use if the check fails

Returns:

the validated floating point value

Throws:

IllegalArgumentException - if any of the elements in value were out of range

NullPointerException - if the value was null