【JAVA】Arrays.asList和List的add方法一起使用报错

使用例子：

import java.util.Arrays;
import java.util.List;

public class test {

    public static void main(String[] args) {
        String[] str1 = {"1", "1", "3", "4"};
        String[] str2 = {"1", "1", "3", "4"};
        List list1 = Arrays.asList(str1);
        List list2 = Arrays.asList(str2);
        list1.addAll(list2);
    }
}

错误信息：

Exception in thread "main" java.lang.UnsupportedOperationException
at java.base/java.util.AbstractList.add(AbstractList.java:153)
at java.base/java.util.AbstractList.add(AbstractList.java:111)
at java.base/java.util.AbstractCollection.addAll(AbstractCollection.java:352)

at com.example.demo.java20180620.test.main(test.java:17)

错误分析：

Arrays.asList这个方法返回的List对象没有重载add、remove。

Arrays.asList返回的ArrayList的源码：

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) {
        a = Objects.requireNonNull(array);
    }

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

    @Override
    public Object[] toArray() {
        return Arrays.copyOf(a, a.length, Object[].class);
    }

    @Override
    @SuppressWarnings("unchecked")
    public <T> T[] toArray(T[] a) {
        int size = size();
        if (a.length < size)
            return Arrays.copyOf(this.a, size,
                                 (Classextends T[]>) a.getClass());
        System.arraycopy(this.a, 0, a, 0, size);
        if (a.length > size)
            a[size] = null;
        return a;
    }

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

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

    @Override
    public int indexOf(Object o) {
        E[] a = this.a;
        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;
    }

    @Override
    public boolean contains(Object o) {
        return indexOf(o) >= 0;
    }

    @Override
    public Spliterator<E> spliterator() {
        return Spliterators.spliterator(a, Spliterator.ORDERED);
    }

    @Override
    public void forEach(Consumersuper E> action) {
        Objects.requireNonNull(action);
        for (E e : a) {
            action.accept(e);
        }
    }

    @Override
    public void replaceAll(UnaryOperator<E> operator) {
        Objects.requireNonNull(operator);
        E[] a = this.a;
        for (int i = 0; i < a.length; i++) {
            a[i] = operator.apply(a[i]);
        }
    }

    @Override
    public void sort(Comparatorsuper E> c) {
        Arrays.sort(a, c);
    }

    @Override
    public Iterator<E> iterator() {
        return new ArrayItr<>(a);
    }
}