java Byte.toString 方法与String.ValueOf(Byte)效率比较

　　

        int times = 10000000;
        Byte[] li = new Byte[times];
        for (int i = 0; i < times; i++) {
            li[i] = (byte) i;
        }

        long timeA = System.currentTimeMillis();
        for (int i = 0; i < times; i++) {
            li[i].toString();
        }

        long timeB = System.currentTimeMillis();

        for (int i = 0; i < times; i++) {
            String.valueOf(li[i]);
        }

        long timeC = System.currentTimeMillis();

        System.out.println("A方法耗时：" + (timeB - timeA));
        System.out.println("B方法耗时：" + (timeC - timeB));

        if (timeB - timeA > timeC - timeB) {
            System.out.println("B方法好");
        } else {
            System.out.println("A方法好");
        }
            

执行结果：

A方法耗时：1303

B方法耗时：239

B方法好

String.valueOf(li[i]);

li[i] 为何变成Object了？不是应该调用String.valueOf(Byte) ?求高手指教