edu.hm.hafner.util

Class Ensure

java.lang.Object

edu.hm.hafner.util.Ensure

public final class Ensure
extends Object

Provides several helper methods to validate method arguments and class invariants thus supporting the design by contract concept (DBC).

Note: the static methods provided by this class use a fluent interface, i.e., in order to verify an assertion a method sequence needs to be called.

Available checks:

• Boolean assertions, e.g., Ensure.that(condition).isTrue();
• String assertions, e.g., Ensure.that(string).isNotEmpty();
• Object assertions, e.g., Ensure.that(element).isNotNull();
• Array assertions, e.g., Ensure.that(array).isNotEmpty();
• Iterable assertions, e.g., Ensure.that(collection).isNotNull();

Author:

Ullrich Hafner

See Also:

Design by Contract (Meyer, Bertrand)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Ensure.ArrayCondition Assertions for arrays.
static class	Ensure.BooleanCondition Assertions for booleans.
static class	Ensure.CollectionCondition Assertions for iterables.
static class	Ensure.ExceptionCondition Assertions for exceptions.
static class	Ensure.IterableCondition Assertions for iterables.
static class	Ensure.ObjectCondition Assertions for objects.
static class	Ensure.StringCondition Assertions for strings.

Method Summary

Modifier and Type	Method and Description
static Ensure.BooleanCondition	that(boolean value) Returns a boolean condition.
static Ensure.CollectionCondition	that(Collection<?> value) Returns a collection condition.
static Ensure.IterableCondition	that(Iterable<?> value) Returns an iterable condition.
static Ensure.ArrayCondition	that(Object[] value) Returns an array condition.
static Ensure.ObjectCondition	that(Object value, Object... additionalValues) Returns an object condition.
static Ensure.StringCondition	that(String value) Returns a string condition.
static Ensure.ExceptionCondition	that(Throwable value) Returns an exception condition.
static void	thatStatementIsNeverReached() Always throws an AssertionError.
static void	thatStatementIsNeverReached(String explanation, Object... args) Always throws an AssertionError.

Methods inherited from class java.lang.Object

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

Method Detail

that

public static Ensure.BooleanCondition that(boolean value)

Returns a boolean condition.

Parameters:

value - the value to check

Returns:

a boolean condition

that

public static Ensure.ObjectCondition that(@CheckForNull
                                          Object value,
                                          @CheckForNull
                                          Object... additionalValues)

Returns an object condition.

Parameters:

value - the value to check

additionalValues - the additional values to check

Returns:

an object condition

that

public static Ensure.IterableCondition that(@CheckForNull
                                            Iterable<?> value)

Returns an iterable condition.

Parameters:

value - the value to check

Returns:

an iterable condition

that

public static Ensure.CollectionCondition that(@CheckForNull
                                              Collection<?> value)

Returns a collection condition.

Parameters:

value - the value to check

Returns:

a collection condition

that

public static Ensure.ArrayCondition that(@CheckForNull
                                         Object[] value)

Returns an array condition.

Parameters:

value - the value to check

Returns:

an array condition

that

public static Ensure.StringCondition that(@CheckForNull
                                          String value)

Returns a string condition.

Parameters:

value - the value to check

Returns:

a string condition

that

public static Ensure.ExceptionCondition that(@CheckForNull
                                             Throwable value)

Returns an exception condition.

Parameters:

value - the value to check

Returns:

an exception condition

thatStatementIsNeverReached

public static void thatStatementIsNeverReached()

Always throws an AssertionError.

thatStatementIsNeverReached

@FormatMethod
public static void thatStatementIsNeverReached(String explanation,
                                                             Object... args)

Always throws an AssertionError.

Parameters:

explanation - a formatted message explaining the assertion

args - Arguments referenced by the format specifiers in the formatted explanation. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero.