为什么List.toArray（）之后不能转换类型？该怎么解决_J2SE

为什么List.toArray（）之后不能转换类型？

Java code

List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();         Map<String, Object> m1 = new HashMap<String, Object>();         m1.put("1","1");         Map<String, Object> m2 = new HashMap<String, Object>();         m2.put("2","2");         list.add(m1);         list.add(m2);         System.out.println(list.toString());         Map[] arr = new HashMap[list.size()];         Object[] objs = list.toArray();         arr = (Map[])objs;

运行代码，出错
Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object;

------解决方案--------------------
返回的本来就是一个Object数组，只不过每一维放的都是HashMap
给你下面这个例子你说明白了

Java code

        Object obj[] = new Object[]{1,2,3};        System.out.println(Integer[].class.isInstance(obj));        System.out.println(Object[].class.isInstance(obj));                Object obj2[] = new Integer[]{1,2,3};        System.out.println(Integer[].class.isInstance(obj2));        System.out.println(Object[].class.isInstance(obj2));//这个输出true是因为Object是Integer的super
------解决方案--------------------
Java codepackage com.j913;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;public class Test2 {    public static void main(String[] args) {        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();        Map<String, Object> m1 = new HashMap<String, Object>();        m1.put("1","1");        Map<String, Object> m2 = new HashMap<String, Object>();        m2.put("2","2");        list.add(m1);        list.add(m2);        System.out.println(list.toString());        Map[] arr = new HashMap[list.size()];        Object[] objs = list.toArray(arr);//这儿，，告诉转换时，Object[]里面存储的是Map，        //不写的话Object[]里面放的都是Object类型的，下一步转换当然是错误的了。因为里面不对应。               arr = (Map[])objs;    }}