关于java.lang.UnsupportedOperationException异常

使用Arrays.asList()去处理一个数组的时候，报错

java.lang.UnsupportedOperationException

String[] arrayStr = new String[4];
arrayStr[0] = "0";
arrayStr[1] = "1";
arrayStr[2] = "2";
arrayStr[3] = "3";
List<String> list = Arrays.asList(arrayStr);
list.clear();

查看源码发现如下：

在Arrays.java, asList()方法是构建了一个ArrayList，但是这个是属于Arrays.ArrayList

@SafeVarargs
public static <T> List<T> asList(T... a) {
  return new ArrayList<>(a);
}

private static class ArrayList<E> extends AbstractList<E>
        implements RandomAccess, java.io.Serializable
    {
        private static final long serialVersionUID = -2764017481108945198L;
        private final E[] a;

        ArrayList(E[] array) {
            if (array==null)
                throw new NullPointerException();
            a = array;
        }

        public int size() {
            return a.length;
        }

        public Object[] toArray() {
            return a.clone();
        }

        public <T> T[] toArray(T[] a) {
            int size = size();
            if (a.length < size)
                return Arrays.copyOf(this.a, size,
                                     (Class<? extends T[]>) a.getClass());
            System.arraycopy(this.a, 0, a, 0, size);
            if (a.length > size)
                a[size] = null;
            return a;
        }

        public E get(int index) {
            return a[index];
        }

        public E set(int index, E element) {
            E oldValue = a[index];
            a[index] = element;
            return oldValue;
        }

        public int indexOf(Object o) {
            if (o==null) {
                for (int i=0; i<a.length; i++)
                    if (a[i]==null)
                        return i;
            } else {
                for (int i=0; i<a.length; i++)
                    if (o.equals(a[i]))
                        return i;
            }
            return -1;
        }

        public boolean contains(Object o) {
            return indexOf(o) != -1;
        }
    }

这个和ArrayList是不同的东西，看下ArrayList

public class ArrayList<E> extends AbstractList<E>
        implements List<E>, RandomAccess, Cloneable, java.io.Serializable
{

也就是说Array.ArrayList并没有实现诸如clear()等方法，固有错误报出