System.arraycopy方法

//native方法，将src的数组从索引从srcPos开始，长度为length,复制到dest数组，索引为destPos，长度为length

public static native void arraycopy(Object src,  int  srcPos,
                                        Object dest, int destPos,
                                        int length);

　

@Test
    void contextLoads() {
        String[] arr1 = {"a1","a2","a3","a4","a5"};
        String[] arr2 = {"b1","b2","b3","b4","b5"};
        System.arraycopy(arr1,1,arr2,1,3);
        for (String s : arr2) {
            System.out.println(s);
        }
        System.out.println("=======================");
        String[] arr3 = {"a1","a2","a3","a4","a5"};
        String[] arr4 = new String[5];
        System.arraycopy(arr3,1,arr4,1,3);
        for (String s : arr4) {
            System.out.println(s);
        }
    }

　运行结果：