Java lang unsupportedoperationexception ошибка

Привет, сегодня я хотел бы поговорить о культуре проектирования. Многие программисты (особенно джуниоры) боятся создать лишний класс, интерфейс и т.п… Причин тому, я уверен, немало, однако эта тема выходит за рамки этого поста. Но как раз из-за этого появляются очень интересные проблемы, о которых я хотел бы сегодня рассказать. Если я тебя заинтриговал — добро пожаловать под кат.

Как пример возьмем JDK интерфейс Iterator.

public interface Iterator<E> {
    
    boolean hasNext();

    E next();

    default void remove() {
        throw new UnsupportedOperationException("remove");
    }

    default void forEachRemaining(Consumer<? super E> action) {
        Objects.requireNonNull(action);
        while (hasNext())
            action.accept(next());
    }

} 

Этот код взят именно из JDK 1.8 не просто так. Дело в том, что в JavaDoc’е к методу remove сказано, что он может кидать UnsupportedOperationException, в случае, если реализация интерфейса его не поддерживает. И на мой взгляд это большая проблема. Конечно, я понимаю, что в JDK она вызвана поддержкой обратной совместимости и уже ничего с этим не сделаешь, ничего не сломав.

Я долго думал, как проиллюстрировать эту проблему. И вот, я обратил свое внимание на нее, когда я приехал в гости к другу. Пока друг удалился в кухню за

пивом

соком, я решил включить кондиционер, он был такой же, как и у меня дома и я без вопросов взял пульт и начал клацать. Не работает. Переподключил конциционер к сети, проверил батарейки в пульте, подошел вплотную — и нечего, мой любимый турбо-режим не работает и все, о чем я и пожаловался другу, когда он вернулся. Но тут-то меня и ждал сюрприз: «А в этой модели нет никаких турбо-режимов», — хладнокровно ответил мне друг. «Как так, вот же кнопка „turbo“», — показываю я другу пульт.

Приблизительно такие же чувства я испытываю когда мне прилетает вот такой вот UnsupportedOperationException. На мой взгляд, эта проблема должна решаться простой иерархией интерфейсов, и если с пультами проблема вызвана нерентабельностью, но ведь у нас таких проблем нет 😉

Спасибо за внимание.
Буду рад коментариям и объективной критике.

How to Fix the Unsupported Operation Exception in Java

Table of Contents

An UnsupportedOperationException is a runtime exception in Java that occurs when a requested operation is not supported. For example, if an unmodifiable List is attempted to be modified by adding or removing elements, an UnsupportedOperationException is thrown. This is one of the common exceptions that occur when working with Java collections such as List, Queue, Set and Map.

The UnsupportedOperationException is a member of the Java Collections Framework. Since it is an unchecked exception, it does not need to be declared in the throws clause of a method or constructor.

What Causes UnsupportedOperationException

An UnsupportedOperationException is thrown when a requested operation cannot be performed because it is not supported for that particular class. One of the most common causes for this exception is using the asList() method of the java.util.Arrays class. Since this method returns a fixed-size unmodifiable List , the add() or remove() methods are unsupported. Trying to add or remove elements from such a List will throw the UnsupportedOperationException exception.

Other cases where this exception can occur include:

• Using wrappers between collections and primitive types.
• Trying to remove elements using an Iterator .
• Trying to add, remove or set elements using ListIterator .

UnsupportedOperationException Example

Here’s an example of an UnsupportedOperationException thrown when an object is attempted to be added to an unmodifiable List :

Since the Arrays.asList() method returns a fixed-size list, attempting to modify it either by adding or removing elements throws an UnsupportedOperationException .

Running the above code throws the exception:

How to Resolve UnsupportedOperationException

The UnsupportedOperationException can be resolved by using a mutable collection, such as ArrayList , which can be modified. An unmodifiable collection or data structure should not be attempted to be modified.

The unmodifiable List returned by the Arrays.asList() method in the earlier example can be passed to a new ArrayList object, which can be modified:

Here, a new ArrayList object is created using the unmodifiable list returned from the Arrays.asList() method. When a new element is added to the ArrayList , it works as expected and resolves the UnsupportedOperationException. Running the above code produces the following output:

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Источник

Unsupported Operation Exception Class

Definition

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Thrown to indicate that the requested operation is not supported.

Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.

Constructors

Constructs an UnsupportedOperationException with no detail message.

A constructor used when creating managed representations of JNI objects; called by the runtime.

Constructs an UnsupportedOperationException with the specified detail message.

Constructs a new exception with the specified detail message and cause.

Constructs a new exception with the specified cause and a detail message of (cause==null ? null : cause.toString()) (which typically contains the class and detail message of cause ).

Fields

Properties

Returns the cause of this throwable or null if the cause is nonexistent or unknown.

(Inherited from Throwable) Class (Inherited from Throwable) Handle

The handle to the underlying Android instance.

(Inherited from Throwable) JniIdentityHashCode (Inherited from Throwable) JniPeerMembers LocalizedMessage

Creates a localized description of this throwable.

(Inherited from Throwable) Message

Returns the detail message string of this throwable.

(Inherited from Throwable) PeerReference (Inherited from Throwable) StackTrace (Inherited from Throwable) ThresholdClass

This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.

This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.

Methods

Appends the specified exception to the exceptions that were suppressed in order to deliver this exception.

(Inherited from Throwable) Dispose() (Inherited from Throwable) Dispose(Boolean) (Inherited from Throwable) FillInStackTrace()

Fills in the execution stack trace.

(Inherited from Throwable) GetStackTrace()

Provides programmatic access to the stack trace information printed by #printStackTrace() .

(Inherited from Throwable) GetSuppressed()

Returns an array containing all of the exceptions that were suppressed, typically by the try -with-resources statement, in order to deliver this exception.

(Inherited from Throwable) InitCause(Throwable)

Initializes the cause of this throwable to the specified value.

(Inherited from Throwable) PrintStackTrace()

Prints this throwable and its backtrace to the standard error stream.

(Inherited from Throwable) PrintStackTrace(PrintStream)

Prints this throwable and its backtrace to the specified print stream.

(Inherited from Throwable) PrintStackTrace(PrintWriter)

Prints this throwable and its backtrace to the specified print writer.

(Inherited from Throwable) SetHandle(IntPtr, JniHandleOwnership)

Sets the Handle property.

(Inherited from Throwable) SetStackTrace(StackTraceElement[])

Sets the stack trace elements that will be returned by #getStackTrace() and printed by #printStackTrace() and related methods.

(Inherited from Throwable) ToString() (Inherited from Throwable) UnregisterFromRuntime() (Inherited from Throwable)

Explicit Interface Implementations

Extension Methods

Performs an Android runtime-checked type conversion.

Источник

Unsupported Operation Exception Class

Definition

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Thrown to indicate that the requested operation is not supported.

Portions of this page are modifications based on work created andВ shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.

Constructors

Constructs an UnsupportedOperationException with no detail message.

A constructor used when creating managed representations of JNI objects; called by the runtime.

Constructs an UnsupportedOperationException with the specified detail message.

Constructs a new exception with the specified detail message and cause.

Constructs a new exception with the specified cause and a detail message of (cause==null ? null : cause.toString()) (which typically contains the class and detail message of cause ).

Fields

Properties

Returns the cause of this throwable or null if the cause is nonexistent or unknown.

(Inherited from Throwable) Class (Inherited from Throwable) Handle

The handle to the underlying Android instance.

(Inherited from Throwable) JniIdentityHashCode (Inherited from Throwable) JniPeerMembers LocalizedMessage

Creates a localized description of this throwable.

(Inherited from Throwable) Message

Returns the detail message string of this throwable.

(Inherited from Throwable) PeerReference (Inherited from Throwable) StackTrace (Inherited from Throwable) ThresholdClass

This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.

This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.

Methods

Appends the specified exception to the exceptions that were suppressed in order to deliver this exception.

(Inherited from Throwable) Dispose() (Inherited from Throwable) Dispose(Boolean) (Inherited from Throwable) FillInStackTrace()

Fills in the execution stack trace.

(Inherited from Throwable) GetStackTrace()

Provides programmatic access to the stack trace information printed by #printStackTrace() .

(Inherited from Throwable) GetSuppressed()

Returns an array containing all of the exceptions that were suppressed, typically by the try -with-resources statement, in order to deliver this exception.

(Inherited from Throwable) InitCause(Throwable)

Initializes the cause of this throwable to the specified value.

(Inherited from Throwable) PrintStackTrace()

Prints this throwable and its backtrace to the standard error stream.

(Inherited from Throwable) PrintStackTrace(PrintStream)

Prints this throwable and its backtrace to the specified print stream.

(Inherited from Throwable) PrintStackTrace(PrintWriter)

Prints this throwable and its backtrace to the specified print writer.

(Inherited from Throwable) SetHandle(IntPtr, JniHandleOwnership)

Sets the Handle property.

(Inherited from Throwable) SetStackTrace(StackTraceElement[])

Sets the stack trace elements that will be returned by #getStackTrace() and printed by #printStackTrace() and related methods.

(Inherited from Throwable) ToString() (Inherited from Throwable) UnregisterFromRuntime() (Inherited from Throwable)

Explicit Interface Implementations

Extension Methods

Performs an Android runtime-checked type conversion.

Источник

Все зло UnsupportedOperationException в примерах

Привет, сегодня я хотел бы поговорить о культуре проектирования. Многие программисты (особенно джуниоры) боятся создать лишний класс, интерфейс и т.п… Причин тому, я уверен, немало, однако эта тема выходит за рамки этого поста. Но как раз из-за этого появляются очень интересные проблемы, о которых я хотел бы сегодня рассказать. Если я тебя заинтриговал — добро пожаловать под кат.

Как пример возьмем JDK интерфейс Iterator.

Этот код взят именно из JDK 1.8 не просто так. Дело в том, что в JavaDoc’е к методу remove сказано, что он может кидать UnsupportedOperationException, в случае, если реализация интерфейса его не поддерживает. И на мой взгляд это большая проблема. Конечно, я понимаю, что в JDK она вызвана поддержкой обратной совместимости и уже ничего с этим не сделаешь, ничего не сломав.

Я долго думал, как проиллюстрировать эту проблему. И вот, я обратил свое внимание на нее, когда я приехал в гости к другу. Пока друг удалился в кухню за пивом соком, я решил включить кондиционер, он был такой же, как и у меня дома и я без вопросов взял пульт и начал клацать. Не работает. Переподключил конциционер к сети, проверил батарейки в пульте, подошел вплотную — и нечего, мой любимый турбо-режим не работает и все, о чем я и пожаловался другу, когда он вернулся. Но тут-то меня и ждал сюрприз: «А в этой модели нет никаких турбо-режимов», — хладнокровно ответил мне друг. «Как так, вот же кнопка „turbo“», — показываю я другу пульт.

Приблизительно такие же чувства я испытываю когда мне прилетает вот такой вот UnsupportedOperationException. На мой взгляд, эта проблема должна решаться простой иерархией интерфейсов, и если с пультами проблема вызвана нерентабельностью, но ведь у нас таких проблем нет 😉

Спасибо за внимание.
Буду рад коментариям и объективной критике.

Источник


public

class
UnsupportedOperationException


Thrown to indicate that the requested operation is not supported.

This class is a member of the

Java Collections Framework.

Summary

Public constructors

public UnsupportedOperationException ()

public UnsupportedOperationException (String message)

public UnsupportedOperationException (String message, 
                Throwable cause)

public UnsupportedOperationException (Throwable cause)

What is hierarchy of java.lang. UnsupportedOperationException?

-java.lang.Object

-java.lang.Throwable

   -java.lang.UnsupportedOperationException

UnsupportedOperationException is Checked (compile time exceptions) and UnChecked (RuntimeExceptions) in java ?

java.lang.UnsupportedOperationException is a RuntimeExceptions in java.

What is UnsupportedOperationException in java?

UnsupportedOperationException is thrown when requested operation is not supported. Example — Modifying unmodifiable list either by adding or removing elements throws UnsupportedOperationException in java.

1. java.util.Arrays.asList method returns fixed size list, i.e. unmodifiable list and Modifying unmodifiable list either by adding or removing elements throws UnsupportedOperationException in java

2. making list unmodifiable using Collections.unmodifiableList and Modifying unmodifiable list either by adding or removing elements throws java.lang.UnsupportedOperationException in java.

3. making set unmodifiable using Collections.unmodifiableSet and Modifying unmodifiable set either by adding or removing elements throws java.lang.UnsupportedOperationException in java

4. making map unmodifiable using Collections.unmodifiableMap and Modifying unmodifiable map either by adding or removing key-value pair throws java.lang.UnsupportedOperationException in java

Scenarios where UnsupportedOperationException may be thrown in java>

Program/Example 1 > java.util.Arrays.asList method returns fixed size list, i.e. unmodifiable list and Modifying unmodifiable list either by adding or removing elements throws UnsupportedOperationException in java

Program/Example 2 >ArrayList — making list unmodifiable using Collections.unmodifiableList and Modifying unmodifiable list either by adding or removing elements throws java.lang.UnsupportedOperationException in java

Program/Example 3 >LinkedList — making list unmodifiable using Collections.unmodifiableList and Modifying unmodifiable list either by adding or removing elements throws java.lang.UnsupportedOperationException in java

Program/Example 4 >HashSet — making set unmodifiable using Collections.unmodifiableSet and Modifying unmodifiable set either by adding or removing elements throws java.lang.UnsupportedOperationException in java

Program/Example 5 >HashMap — making map unmodifiable using Collections.unmodifiableMap and Modifying unmodifiable map either by adding or removing key-value pair throws java.lang.UnsupportedOperationException in java

Program/Example 6 >LinkedHashSet  — making set unmodifiable using Collections.unmodifiableSet and Modifying unmodifiable set either by adding or removing elements throws java.lang.UnsupportedOperationException in java

Program/Example 7 > Hashtable — making map unmodifiable using Collections.unmodifiableMap and Modifying unmodifiable map either by adding or removing key-value pair throws java.lang.UnsupportedOperationException in java

Map hierarchy in java — Detailed — HashMap, Hashtable, ConcurrentHashMap, LinkedHashMap, TreeMap, ConcurrentSkipListMap, IdentityHashMap, WeakHashMap, EnumMap classes

Program/Example 8 >

ConcurrentSkipListMap — making map unmodifiable using Collections.unmodifiableMap in java and Modifying unmodifiable map either by adding or removing key-value pair throws java.lang.UnsupportedOperationException in java

HashMap vs Hashtable vs LinkedHashMap vs TreeMap — Differences

Program/Example 9 >

TreeMap — making map unmodifiable using Collections.unmodifiableMap and Modifying unmodifiable map either by adding or removing key-value pair throws java.lang.UnsupportedOperationException in java

HashMap vs Hashtable vs LinkedHashMap vs TreeMap — Differences

Program/Example 10 >

ConcurrentHashMap — making map unmodifiable using Collections.unmodifiableMap and Modifying unmodifiable map either by adding or removing key-value pair throws java.lang.UnsupportedOperationException in java

HashMap and ConcurrentHashMap — Similarity and Differences

HashMap vs Hashtable vs LinkedHashMap vs TreeMap — Differences

Program/Example 11 >LinkedHashMap — making map unmodifiable using Collections.unmodifiableMap and Modifying unmodifiable map either by adding or removing key-value pair throws java.lang.UnsupportedOperationException in java

HashMap vs Hashtable vs LinkedHashMap vs TreeMap — Differences

Map hierarchy in java — Detailed — HashMap, Hashtable, ConcurrentHashMap, LinkedHashMap, TreeMap, ConcurrentSkipListMap, IdentityHashMap, WeakHashMap, EnumMap classes

How to Avoid or Solve UnsupportedOperationException in java >

Never try to modify list, set or map which has been made unmodifiable.

• Never modify list returned by  java.util.Arrays.asList method to avoid java.lang.UnsupportedOperationException in java

• Never modify list which has been made unmodifiable using Collections.unmodifiableList method to avoid java.lang.UnsupportedOperationException in java

• Never modify set which has been made unmodifiable using Collections.unmodifiableSet method to avoid java.lang.UnsupportedOperationException in java.

• Never modify map which has been made unmodifiable using Collections.unmodifiableMap method to avoid java.lang.UnsupportedOperationException in java.