java - Object.clone() 不应该需要显式转换吗？

Question

为什么不需要 Object.clone() 调用需要显式转换？这不是“向下转换总是需要和显式转换”规则的异常(exception)吗？我使用 javac 命令行和带有 JDK1.6.0_29 的 Eclipse Helios 编译并成功运行了以下代码。

public class Main {

    public static void main(String[] args) {
        byte[] original = { 1, 2, 3, 4 };
        byte[] copy = original.clone();

        for (byte b : copy) {
            System.out.print(b + " ");
        }

        int[] originalInt = { 11, 22, 33, 44 };
        int[] copyInt = originalInt.clone();

        for (int i : copyInt) {
            System.out.print(i + " ");
        }

        String[] originalStr = { "1", "2", "3", "4" };
        String[] copyStr = originalStr.clone();

        for (String s : copyStr) {
            System.out.print(s + " ");
        }

        Main[] originalMain = { new Main() };
        Main[] copyMain = originalMain.clone();

        for (Main m : copyMain) {
            System.out.print(m + " ");
        }
    } // end method main

} // end class Main

Answer 1

您没有调用 Object.clone()。您正在调用 T[].clone()，它被覆盖以返回 T[]。

JLS 10.7 Array Members :

The members of an array type are all of the following:

• The public method clone, which overrides the method of the same name in class Object and throws no checked exceptions. The return type of the clone method of an array type T[] is T[].