java异常java.lang.UnsupportedOperationException解决方法

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最新推荐文章于 2025-05-19 19:12:52 发布

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分类专栏：报错解决 java代码文章标签： java异常 java异常解决办法 java报错解决方法 UnsupportedOperationException java.lang.UnsupportedOperationExcep

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本文解析了 Java 中 UnsupportedOperationException 的出现原因及解决办法，介绍了 Collections.emptyList() 的内部实现，并提供了避免该异常的具体示例。

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1.java异常报错如下

java.lang.UnsupportedOperationException
	at java.util.AbstractList.add(AbstractList.java:148)
	at java.util.AbstractList.add(AbstractList.java:108)
	at com.hiss.entity.binary.response.FreezeUserResponse.toDataModel(FreezeUserResponse.java:96)
	at com.hiss.service.impl.HissNewOsReceiveService.receiveService(ReceiveService.java:204)
	at com.hiss.service.impl.HissNewOsReceiveService$$FastClassBySpringCGLIB$$556c3f60.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
	at org.springframework.aop.interceptor.AsyncExecutionInterceptor$1.call(AsyncExecutionInterceptor.java:115)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

2.异常解决方法如下
private List users = Collections.emptyList();
执行remove，add等method时，抛出此异常，本人将上述代码改为：
private List users = new ArrayList();

3.异常原因如下
Collections.emptyList()中的emptyList继承AbstractList，remove、add等方法AbstractList中是默认throw UnsupportedOperationException而且不作任何操作

    @SuppressWarnings("unchecked")
    public static final <T> List<T> emptyList() {
        return (List<T>) EMPTY_LIST;
    }

emptyList继承AbstractList

 private static class EmptyList<E>
        extends AbstractList<E>
        implements RandomAccess, Serializable {
        .....
}

remove、add等方法AbstractList中是默认throw UnsupportedOperationException而且不作任何操作

    /**
     * {@inheritDoc}
     *
     * <p>This implementation always throws an
     * {@code UnsupportedOperationException}.
     *
     * @throws UnsupportedOperationException {@inheritDoc}
     * @throws ClassCastException            {@inheritDoc}
     * @throws NullPointerException          {@inheritDoc}
     * @throws IllegalArgumentException      {@inheritDoc}
     * @throws IndexOutOfBoundsException     {@inheritDoc}
     */
    public E set(int index, E element) {
        throw new UnsupportedOperationException();
    }

    /**
     * {@inheritDoc}
     *
     * <p>This implementation always throws an
     * {@code UnsupportedOperationException}.
     *
     * @throws UnsupportedOperationException {@inheritDoc}
     * @throws ClassCastException            {@inheritDoc}
     * @throws NullPointerException          {@inheritDoc}
     * @throws IllegalArgumentException      {@inheritDoc}
     * @throws IndexOutOfBoundsException     {@inheritDoc}
     */
    public void add(int index, E element) {
        throw new UnsupportedOperationException();
    }

    /**
     * {@inheritDoc}
     *
     * <p>This implementation always throws an
     * {@code UnsupportedOperationException}.
     *
     * @throws UnsupportedOperationException {@inheritDoc}
     * @throws IndexOutOfBoundsException     {@inheritDoc}
     */
    public E remove(int index) {
        throw new UnsupportedOperationException();
    }